lint: parse but otherwise ignore C23 attributes

The C23 attributes are only parsed before an expression in an expression
statement, as a proof of concept. Other places will follow later.

lint: in C23 mode, support the nullptr constant

lint: in C23 mode, support the keywords 'bool', 'false' and 'true'

lint: measure the alignment in bytes, not bits

While measuring the alignment in bits makes sense when building a struct
type with bit-fields, in all other places it is more confusing than
helpful.

The only visible change is that in debug mode, the format of type sizes
and alignment changed. Since the size of all complete types is a
multiple of a byte (as defined in the C standard), sizes and alignments
are reported in bytes as well. Only while a struct is being built, the
type size may include an additional '+x' for the bits of a bit-field.

lint: support _Alignas and __attribute__((__aligned(4)))

lint: merge function call operators 'CALL' and 'ICALL'

lint: inline accessor macros for tnode_t

lint: inline accessor macros for type_t

lint: clean up comments, use typedefs

lint: internally store case label values in order of appearance

lint: remove unneeded checks for left and right operands

lint: use fewer struct keywords

lint: clean up string parsing and snprintb check

lint: make function call arguments directly accessible

Previously, the arguments of a function call expression were arranged in
a linear tree structure, from right to left. To allow easier access to
the arguments, store them in an array instead.

lint: remove excessive empty lines

lint: keep strings in their source representation

This allows further analysis depending on whether individual characters are
escaped as octal, hexadecimal or not at all.

lint: use standard buffer for storing string values

No functional change.

lint: do not remember content of wide string literals

The plain char literals are needed for checking printf/scanf format
strings; lint has no similar check for wide strings. These format
strings are checked by modern compilers, making this check less
relevant.

lint: rename symt_t to symbol_kind

It was confusing to have two kinds of "symbol type" (s_type and s_symt),
so rename all related identifiers to be more distinctive.

No functional change.

lint: clean up enum constants for designators

In intializers and offsetof, both struct and union members are handled
in the same way, thus there is no need to distinguish them.

lint: allow complex offsetof(type, member-designator)

Both GCC 11 and Clang 8 accept member-designators that are not
identifiers but designator sequences, such as in 'offsetof(struct stat,
st_atim.tv_sec)', so make lint accept them as well.

lint: remove redundant parentheses, braces and comments

Rename the functions for folding constant expressions, to make the
comments redundant.

lint: in declarations, replace tab with space

Previously, in some cases, the keywords 'const' or 'struct' were
followed by a tab, which doesn't make sense.

No functional change.

lint: re-wrap comments

No functional change.

lint: rename NOSCL to NO_SCL

For symmetry with NO_TSPEC. No functional change.

lint: remove preprocessor magic from definition of operators

No binary change.

lint: prevent invalid memory access when checking an expression

In check_expr_misc, the left and right operands of an expression were
accessed even in the case of CON (constant), STRING (string literal) and
NAME (identifier), which led to invalid values in pointer variables.
These invalid values were not used though, but technically they invoked
undefined behavior.

Precede each access to the operands with a check that the expression
indeed has operands, except in those cases where the operand is known to
have operands by only looking at the code of the current function.

lint: make diagnostics about ANSI C more international

lint: distinguish between arguments and parameters

lint: clear global variable 'dcs' after use

Having unnecessarily set members is confusing during debugging.

lint: only generate err-msgs.h in debug mode

lint: extract 'vararg' and 'prototype' flags from global 'dcs'

These flags are only relevant for parameter lists, so add a separate
type for it.

No functional change.

lint: work around a possible compiler error on arm and powerpc

lint: add detailed logging for finding memory allocation bugs

lint: clean up comments, add a test for the '?:' operator

lint: merge duplicate code for checking duplicate type qualifiers

lint: use separate types for parsing pointer types and type qualifiers

The documentation of the previous 'qual_ptr_t' was misleading, as that
type was used for other type qualifier lists as well, even if these were
not related to pointer types.

lint: _Thread_local is a storage class, not a type qualifier

lint: indent copyright lines consistently

lint: reduce code size for handling lint comments

lint: reject _Noreturn if it occurs in invalid places

C11 introduced _Noreturn as a function-specifier, not as a type
attribute. The latter may occur in more places.

lint: don't treat 'inline' as a storage class

The additional conflict in the grammar is in the same place as the other
conflicts, as T_SCLASS and T_FUNCTION_SPECIFIER are now separate tokens.

No functional change.

lint: update wording in diagnostic for C99

lint: merge duplicate code for getting the name of an operator

lint: add debug logging for symbol kinds in the parser

An identifier can refer to a variable, type, member, tag or label.
Switching between these namespaces is tightly coupled with the
evaluation order of the grammar rules.

lint: miscellaneous cleanup

lint: clean up redundant casts

lint: rename uppercase QUAD to LLONG

No binary change.

lint: add initial support for C23

Required by xsrc/external/mit/MesaLib.old, brw_eu_validate.c, which
initializes a struct using empty braces: 'return (struct string){};'.

lint: clean up variable names relating to structure padding

lint: rename 'quad' to 'signed int' or 'unsigned int'

No functional change.

lint: use unsigned int for struct alignment

This gets rid of 'unsigned short', which saved a few bytes of memory but
was inconvenient to deal with.

No functional change.

lint: clean up variable names

lint: clean up comments in lint1.h

lint: clean up names related to declaration levels

The previous prefix 'DK_' (declaration level kind) had a conflict with
the 'DK_' (designator kind) in init.c, so change the prefix to 'DLK_'.
The new name for dinfo_t is decl_level, which is more expressive.

No functional change.

lint: replace macro for unique identifiers with function

No functional change.

lint: clean up handling of declarations

No functional change.

lint: clean up member names of declaration levels

No functional change outside debug mode.

lint: use standard terminology for bit-field width

No functional change.

lint: enhance debug output for diagnostics

Only print the debug message if the diagnostic is active, which is
relevant for c99ism, c11ism and gnuism.

Print more details about the diagnostic or query.

lint: reduce memory allocations

The type val_t has the same size as the tn_s member in the same union.

No functional change.

lint: add query for comparing 'char' with plain integers

lint: miscellaneous clean-ups

No binary change, except for line numbers in assertions.

lint: rename type_t.t_str to t_sou

The name 't_str' could have meant 'string' or 'struct'. Since both
struct and union types have members, rename it to 't_sou'.

No functional change.

lint: use __printflike

lint: replace INTERNAL_ERROR with plain assert

lint: add support for the C11 type qualifier '_Atomic'

That keyword can be used as a type specifier as well, support for that
will be added later.

lint: use fewer abbreviations

No binary change except for line numbers in assertions in decl.c.

lint: remove custom memory allocator

Besides adding complexity, the custom memory allocator didn't invalidate
freed memory, which made it harder to find possible use-after-free bugs.

lint: add hyphen to adjective 'old-style'

lint: rename dcs manipulation functions to be clearer

No functional change.

lint: add additional queries that are not enabled by default

In the last 18 months, several lint warnings have been made adjusted to
allow common usage patterns. For example, lint no longer warns about a
constant condition in the statement 'do { ... } while (false)' (message
161), as this pattern is well-known in statement-like macros, making it
unlikely that the 'false' is a mistake. Another example is casts
between unequal pointer types (message 247) for a few well-known
patterns that are unlikely to be bugs.

Occasionally, it is useful to query the code for patterns or events that
would not justify a warning. These patterns are modeled as predefined
queries that can be selected individually, in addition to and
independently of the existing warnings and errors.

New queries can be added as needed, in the same way as new warnings.
Queries that are deemed no longer used can be deactivated in the same
way as warnings that are no longer used.

As long as none of the queries is enabled, they produce a minimal
overhead of querying a single global variable. Computations that are
more expensive than a few machine instructions should be guarded by
any_query_enabled.

https://mail-index.netbsd.org/source-changes-d/2022/06/28/msg013716.html

ok christos@

lint: move error handling code from main1.c to err.c

No functional change.

lint: rename olwarn and LWARN_BAD to be more expressive

No functional change.

lint: investigate why lint only warns about some constant conditions

Noticed in lex.c, in the macro kwdef, where lint complains about the
condition containing '||' but not about the conditions containing only
'>' or '=='.

lint: migrate gflag to allow_gcc

No functional change.

lint: fix assertion failure on duplicate qualifiers from __typeof__

lint: distinguish between storage class and declaration kind

These types overlap but are not the same.

No functional change.

lint: rename dinfo_t.d_offset to d_offset_in_bits

Most often, offsets are measured in bytes, so better embed the unit in
the variable name.

No functional change.

lint: extract is_member into separate function

No functional change.

lint: disambiguate sym_t.s_value

Having a single variable for 4 different purposes with different types
makes the code unnecessarily hard to follow.

No functional change.

lint: split CTCONST into BOOL_CONST and ENUM_CONST

Having a unified compile-time constant "storage class" made the code
more difficult to understand.

No functional change.

lint: inline member access macros for sym_t

Having the 'u.' explicitly in the code serves as a reminder that these
members are only defined under certain conditions.

No functional change.

lint: use appropriate alignment on both the host and target platform

lint: rename dinfo_t.d_next to d_enclosing

The name d_next gave the wrong impression that the declaration infos
would be independent of each other, but they are nested.

No functional change.

lint: merge duplicate code for handling plain and wide strings

No functional change. As before, the string literals "1" "2" "3" are
not concatenated from left to right, instead concatenation starts with
"23" and then proceeds to "123".

lint: unabbreviate two more members of sym_t

No functional change.

lint: remove unused enumeration details from symbol type

No functional change.

lint: unabbreviate some fields in sym_t

No functional change.

lint: clean up memory management for string buffers

There is no reason to duplicate all the work that is already done by the
memory allocator.

No functional change.

lint: clean up memory allocation

No functional change.

lint: rename ARG to OLD_STYLE_ARG

Pre-C90 argument declarations have been old for more than 30 years now,
so mention that fact in the constant name. This reduces potential
confusion with other occurrences of the words 'arg' or 'argument'.

No functional change.

lint: drop compatibility with C90

Since tools/README 1.5 from 2022-02-03, the tools no longer need to be
compatible with C90, they may now use C99 features. Lint had used
<stdbool.h> and snprintf already.

No functional change.

lint: don't try to trick mathematics by defining ZERO to a nonzero value

No binary change.

lint: clean up lex.c

Rename 'struct kwtab' to 'struct keyword' since a single keyword is not
a whole keyword table.

Sync comment for lex_name with reality: sbuf_t no longer contains the
hash value.

Remove redundant tests for EOF, as EOF is neither a space nor a digit
nor an xdigit.

No functional change.

lint: remove spaces around bit-field colon

As seen in /usr/share/misc/style.

No binary change.

lint: fix check for function calls in strict bool mode

Previously, if a function call occurred in the controlling expression,
its return type could be any scalar, not just bool. This was against
the goal of strict bool mode, which makes bool a separate and
incompabile type to all other types. For example, it would allow
controlling expressions like 'strcmp(a, b)' without the usual '!= 0',
but only if at least one of 'a' and 'b' came from a macro definition
from a system header.

The fix is that the decision of whether the type of the controlling
expression may be scalar is no longer based on the operand types but on
the main operator of the controlling expression.

lint: enter full C90 compatibility mode

The C99 comment in tree.c:3468 has been there since 2017-03-06, without
anyone complaining that their compiler would not handle it.

Strangely, running GCC 10.3.0 in '-std=c90' mode does not complain about
declarations after statements, '-Wdeclaration-after-statement' is needed
separately.

No functional change.

lint: allow [*] everywhere where [] and [integer] are allowed

It's a seldom used feature, but now it's at least consistent.

lint: remove unused function for generic messages

The function message_at is still used, for information about previous
occurrences of a symbol.

lint: fix a few lint warnings about type conversions

A simple 'unsigned int' is more than enough for representing the size of
a bit-field, as well as the maximum alignment of any type.

No functional change.

lint: un-abbreviate unsigned integer types

No functional change.

lint: expand macro in string concatenation

No functional change.

lint: inline msb

This reduces the binary size on x86_64 by about 500 bytes.

No functional change.

lint: merge duplicate code for binary operator

No functional change.

lint: save some memory

Before lint1.h 1.47 from 2021-01-02, adjacent bit-field struct members
shared storage. Restore that using smaller types.

No functional change.

lint: remove hash value from symbol buffer

Conceptually, a symbol buffer does not need to remember its hash value
since that belongs to the symbol table. This makes the code for the
symbol table simpler. The number of hash calculations increases by
about 5%, which is negligible.

No functional change.

lint: improve support for __int128_t and __uint128_t

For the .ln files, I chose the letter 'J' to represent the 128-bit
integer types since it is close to 'I' for int. The naming of 'L' for
'long' is obvious, but 'Q' for 64-bit integers is a quad-16-bit word,
which is an unusual measurement unit nowadays. One benefit of choosing
'J' is that the next letter, 'K' can then be used for 256-bit integer
types.

Support for 128-bit integer types is still very basic. Plus, it is only
supported on LP64 platforms, which means that lint cannot be
cross-compiled to check for an LP64 platform while running on an ILP32
platform.

lint: merge duplicate code for generating unqualified type

This is a preparation for fixing the wrong warnings in msg_115.c.

No functional change.

lint: rename cstk_t to control_statement

Rename the variables as well. Their previous name 'ci' was not easy to
understand, the 'i' may have meant 'stack item'. The new name 'cs'
simply means 'control statement'.

No functional change.

lint: remove a few unnecessary abbreviations

No functional change.

lint: make offset and alignment positive numbers

There's no use case for negative alignment or offsets in structures.

No functional change.

lint: rename grammar rule 'declaration' to 'declaration_or_error'

This prepares for merging the duplicate code from top_level_declaration.
The code coverage outside cgram.y is exactly the same as before.

No functional change.

lint: rename clrtyp/deftyp to begin_type/end_type

The abbreviations clr/def did not make it obvious that these two
functions or grammar rules form pairs.

No functional change.

lint: constify keyword in lexer

No functional change.

lint: rename type generic_association_types to generic_association

The word 'types' was misleading and unnecessary.

No functional change.

lint: rename dinfo_t.d_stralign to d_sou_align_in_bits

When talking about alignment, offset and size of a type, the measurement
unit must be mentioned in the variable name, especially when it differs
from the standard unit of measurement, which is a byte, not a bit.

No functional change.

lint: in strict bool mode, allow mixed types in generated C code

This allows flex lexers to be run through lint in strict bool mode.

lint: document lint1_type.t_is_enum

Enum types are subject to implicit conversions, as opposed to struct,
union, pointer and function types.

lint: rename pqinf_t to qual_ptr and clean up code

The 'inf' from the type name meant 'information' and was redundant. Each
object of that type represents a single pointer level, which made the
documentation about 'pointers' a bit confusing.

The members of struct qual_ptr are now in the canonical reading order,
which is 'const volatile pointer'.

No functional change.

lint: fix result type of _Generic expressions

lint: fix type of pqinf.p_pcnt

A counter that can either be 0 or 1 and is never incremented is not
really a counter, it's a flag.

No functional change.

lint: rename val_t.v_unsigned to avoid confusion

The name v_unsigned suggested that the value would be interpreted as
unsigned, which was wrong. Whether a value is signed or unsigned is
decided by v_tspec instead.

Revert the previous commit for boolen constants since their value is
already interpreted as unsigned, and there is no need for any warning
about differences between traditional C and ANSI C since the _Bool type
has only been added ten years later in C99.

The code for printing a tree node was also confused by this struct
member, even with its old name v_ansiu. That code will be fixed in a
follow-up commit.

No functional change.

lint: rename val_t.v_ansiu to v_unsigned

When lint was written in 1995, traditional C was still nearby since C90
had been around for only 5 years. 26 years later, almost all code
adheres to C90 or even C99 or C11, therefore "C90 or later" can safely
be assumed as the default.

No functional change.

lint: replace undefined behavior with assertion failure

Triggered by this malformed code:

struct{int;

lint: replace array access with function calls

First and foremost, the test d_c99_complex_split accessed the array
qlmasks out-of-bounds, with an index of 128 for the type 'double
_Complex'. This invoked undefined behavior since the maximum allowed
index was 64.

Replacing the raw array accesses with function calls allows for bounds
checks to catch these errors early.

Determining the value bits for a 'double _Complex' does not make sense
at all since it is not an integer type. This means that lint didn't
handle these types correctly for several years. Support for int128_t
has been added in inittyp.c 1.12 from 2018-09-07, support for _Complex
has been added in inittyp.c 1.9 from 2008-04-26.

Determining the value bits for an int128_t would make sense, but the
unit tests don't contain examples for this type since at the moment all
unit tests must produce the same results on 32-bit and 64-bit platforms,
and the 32-bit platforms don't support int128_t.

lint: warn about unreachable case labels for '&&'

See octeon_gmxreg.h 1.2 from 2020-06-18 for an example, where
RXN_RX_INBND_SPEED was cleaned up without adjusting the corresponding
code in octeon_gmx.c.

branches: 1.100.2;
lint: remove redundant CONSTCOND

In do-while-0 loops, these are no longer needed since tree.c 1.202 from
2021-01-31.

lint: rename parameter to diagnostic functions and macros

The first parameter is not just an arbitrary number, it's a message ID.

lint: align the member access macros for tnode_t

lint: add error_at, warning_at, message_at

Right now there are several places in the code that use the global
variable curr_pos for passing a parameter to the diagnostic functions.
That's not what global variables are for.

Make it easy for the code to migrate to the parameter-passing style.

No functional change.

lint: document wrong location information in diagnostics

lint: add support for C11-isms such as int[static 3]

lint: use distinct struct tags for type_t in lint1 and lint2

Having two similar but still different definitions of 'struct type' is
unnecessarily confusing. Exchange this confusion for 8 lines of
straight-forward preprocessing code.

lint: prepare renaming of 'struct type'

It's confusing to have the same struct tag in both lint1 and lint2, with
mostly the same members, but also some differences. Before actually
changing this, I reviewed all occurrences of the word 'type' in the
code.

No functional change.

lint: reduce memory usage

No functional change.

lint: rename mbl to memory_block

No functional change.

lint: rename LERROR to INTERNAL_ERROR

The '#ifndef' in tyname.c is meant to distinguish between lint1 and
lint2, it is not meant to be defined from anywhere outside the lint code
itself.

No functional change.

lint: rename members of struct control_statement to be more expressive

C99 does not define names for the head parts of the 'for' statements, it
just calls them clause-1, expression-2 and expression-3. Therefore the
rather abstract name 'expr3'.

No functional change.

lint: rename pushctrl and popctrl to be more expressive

While here, remove the magic number 0 that in this context means
"function body".

No functional change.

lint: fix reachability for constant controlling expression in for loop

lint: fix reachability computation in if statements

Previously, only loop statements were considered for reachability. This
ignored the possibility of an early return in an if statement, or
unreachable branches.

lint: rename c_rchif to c_reached_end_of_then

No functional change.

lint: rename c_cont to c_continue

No functional change.

lint: document the precise meaning of control_statement.c_break

No functional change.

lint: rename i_infinite to i_maybe_endless

Not every loop that has 'while (1)' is an endless loop. It may still
contain a 'return' somewhere.

lint: fix wrong 'falls off bottom' after return in do-while

lint: rename d_fargs, d_fdpos and d_fpsyms to be less abbreviated

No functional change.

lint: rename d_nedecl to d_nonempty_decl

No functional change.

lint: rename d_rdcsym to d_redeclared_symbol

No functional change.

lint: rename clst to case_labels

No functional change.

lint: document the struct for declarations more precisely

No functional change.

lint: rename in_bit to in_bits

No functional change.

lint: document the initialization of an object in more detail

This will help fixing the bugs that are currently demonstrated in
msg_168.c and d_struct_init_nested.c.

lint: clean up documentation of dinfo_t

No functional change.

lint: rename dinfo_t members to be more expressive

While here, sync redundant but diverging comments, split
multi-assignments and initialize the members in declaration order.

No functional change.

lint: rename 'blklev' to 'block_level'

No functional change.

lint: fix off-by-one error in 'case 3...5'

According to the GCC documentation[1], the high end of the range is
inclusive as well, which makes sense since otherwise there would be no
way of specifying a range that includes the maximum representable
number.

Since the range is not used at all in the code, none of the tests could
possibly fail.

[1] https://gcc.gnu.org/onlinedocs/gcc/Case-Ranges.html

No functional change.

lint: replace wrong comment with assertion

The broad type of a value is indeed stored in the value itself, in the
member v_tspec. For nodes that refer to this value, it is redundantly
stored, it always equals tn->tn_type->t_tspec.

After initialization, neither tn->tn_type nor val->v_tspec are modified.
This is not ensured by the compiler but has to be analyzed manually.

No functional change.

lint: rename is_nonzero to constant_is_nonzero

The new function name emphasizes that the given node must have the
operator CON.

No functional change.

lint: do not warn about constant expressions involving sizeof

These expressions are indeed constant for a specific platform, but on
another platform their value may change. This makes them unsuspicious
and legitimate for portable code.

Seen in rump_syscalls.c, as 'sizeof(int) > sizeof(register_t)'.

lint: change spelling of initialisation to initialization

That's the wording from the ISO C99 standard.

lint: rename storage class constants to be more expressive

No functional change.

lint: rename t_isenum and t_aincompl to be more expressive

No functional change.

lint: rename tenum_t and its members to be more expressive

lint: rename str_t and its members to be more expressive

No functional change.

lint: replace cryptic sym.s_rimpl with expressive name

No functional change.

lint: fix two wrong error messages in strict bool mode

The strict bool mode gets complicated because for system headers the
rules need to be relaxed since they cannot be changed easily, often not at all.

Still, if lint validates a program in strict bool mode, that program
must run with equal behavior regarding boolean expressions even on a
pre-C99 platform.

lint: clean up member names of control_structure and comments

lint: extend a few message comments

lint: replace integer constant expressions with true and false

LINTFLAGS=-gST make lint, with manual review.

The error messages from lint are all correct, they are not complete
though. The return value of a function returning bool may still be
compared to the integer 0.

lint: in strict bool mode, integer constants do not have type bool

Previously, lint1 allowed integer constants such as 0 and 1 to be used
as bool constants. This was only half-baked since after fixing all
error messages from that strict mode, there may still be integer
literals in the code that should be replaced with true or false. This
would stop a migration from int to bool in the middle, leaving
inconsistent code around.

To find the remaining type inconsistencies, treat integers and bool as
completely incompatible, even for compile time constants.

lint: replace 0 and 1 with false and true, where appropriate

Change in behavior: Passing the option -h exactly 4294967296 times or
any multiple thereof is no longer equivalent to passing it never at all,
it is now equivalent to passing it once. See main2.c, hflag++ for the
actual change.

Other than that, no functional change intended.

A very large portion of the code already conformed to the requirements
of the strict bool mode. The only missing thing was using the constant
literals false and true instead of 0 and 1. For sure there are some
integer literals left that can be converted. For now, all literals that
appeared in the form " = 0" or " = 1" have been replaced.

lint: merge duplicate code for non-zero detection

lint: fix typos and other minor stylistic issues

lint: rename cstk to cstmt

Most of the code that deals with control statements is only interested
in the innermost control statement, and not if that is a stack or not.
Therefore, emphasize that part in the variable name.

The member c_next was confusing since the "direction" of this "next
element" was ambiguous. In a sequence of if statements, the "next"
element could have equally been the following one, not the surrounding
one.

lint: rename t_ispacked to t_packed and d_ispacked to d_packed

It's shorter, and the other flags of the type or declaration also don't
have "is" in their names. Except for t_isenum, but that's because there
is a macro named t_enum that would interfere with that name.

lint: rename type.t_isfield to t_bitfield

lint: in DEBUG mode, verify printf parameters for messages

Since several years GCC validates printf-style strings, and there is no
reason not to let GCC do that work. This prevents bugs like the
segmentation fault that was fixed in tree.c 1.109 from 2021-01-01.

By default, lint is compiled with DEBUG off, but it's easy enough to
compile it in debug mode once in a while.

lint: fix lint warning 161 "constant in conditional context"

lint: use bool instead of u_int:1 in structures

Better late than never.

lint: un-export struct istk

lint: inline STRUCT_ASSIGN

This had only been necessary for some pre-C90 compilers.

lint: un-abbreviate s_dpos, s_spos and s_upos

lint: un-abbreviate s_field, s_keyw and s_xsym

lint: un-abbreviate parenthesized and _strg

lint: rename remaining _nxt members to _next

lint: rename more _nxt members to _next

lint: rename symt_t constants

There's no need to abbreviate them, furthermore FMOS was imprecise.

lint: rename s_nxt to s_next

lint: reduce verbosity of assertions

Having 2 lines of source code per assertion is too much, especially
since most of this code is redundant anyway. Extract the common code
and the additional negation into a simple function instead.

lint: rename istk_t.i_cnt to i_remaining

lint: fix typo in comments

lint: fix indentation and alignment that used space-tab

lint: spell check

lint1: remove unused t_field

Add __thread/tls_model attribute

branches: 1.30.14;
teach lint __attribute__((__unused__))

branches: 1.29.6;
typo in comment

only fill memory with junk if BLKDEBUG

branches: 1.27.4;
Allow linted comments to take an argument that defines which error to suppress.

rename enum_t to avoid rpc/types.h lossage.

branches: 1.25.2; 1.25.8;
Always use our own align macro and explain a bit more why this is bogus.

recognize struct __packed x { }; in addition to struct x { } __packed;

understand __attribute__((__packed__)) and __packed.

Ignore restrict in the contexts where const and volatile is allowed.
No validation for the use (e.g. that it is used on a pointer), but
enough to not stop valid C99 programs.

fix const and volatile printing in types.

preliminary _Complex support.
NB: Does not really understand type conversions between complex and doubles.

branches: 1.19.20;
in several comments:
implizit -> implicit
explizit -> explicit

Handle C99 array range initializers:

type a[] = { [lo ... hi] = c }:

Factor out tyname() so that it can be used both by lint1 and lint2.
Since type_t is different between lint1.h and lint2.h include the
appropriate file depending on the pass. Make the argument mismatch
error print the type names of the types involved. Now that we have
a tyname() function we can fix the rest of the pass2 warnings to be
more explanatory, but not now.

fix typo

support for c99 style and gnu style structure and union named initializers.

Minimize diffs with my C99 capable version [this commit does not include
C99 support.

- turn lerror() into a macro so that the filename and the line number of the
error are printed before we abort.
- recurse in type printing to provide the proper type name.

Replace u_quad_t with uint64_t and quad_t with int64_t, and use
<inttypes.h> to get those type definitions. These types are more
portable, and a little more sane to do autoconf tests for.

Provide a placebo default for ALIGN() for hosts which don't have this.

Don't use fd_set to keep track of errors to ignore. Doing so relies on
overriding FD_SETSIZE. Not overriding it makes it stomp all over memory
(which caused the debug outputs we've seen lately).
It used to work, but toolification of lint broke it.

fix up NetBSD RCS Ids to match the standard, and the leading comment as
to match as well. No functional changes.

branches: 1.9.8;
implement (hack in) symbol (function and variable) renaming, so that
the function renaming tricks currently needed by libc can be tolerated
by lint. This needs some cleanup, but it appears to work.

branches: 1.8.2;
Splice a union in the type data structure. Some of the members can be `in use'
simultaneously, e.g. an enumerated bit-field.

* recognize that pointers to identical unnamed and untyped structs,
unions, and enums are, in fact, identical. This is done by tagging
each of unnamed and untyped structure, union and enum with a unique
position of creation, which is used as a unique identifier that
when determine whether or not a pair of structures, unions, or enums
are identical.

don't print warnings about unused variables or arguments in compound
statements which contain asm statements.

prototypes override old style function definitions
this is a gnu extension to ansi c

added inline keywords
"inline" is enabled by -g, "__inline" and "__inline__" are always available

prefixed members of dinfo_t with 'd_'

RCS id cleanup

branches: 1.1.1;
Initial revision

lint: in C23 mode, support the nullptr constant

lint: in C23 mode, support the keywords 'bool', 'false' and 'true'

lint: measure the alignment in bytes, not bits

While measuring the alignment in bits makes sense when building a struct
type with bit-fields, in all other places it is more confusing than
helpful.

The only visible change is that in debug mode, the format of type sizes
and alignment changed. Since the size of all complete types is a
multiple of a byte (as defined in the C standard), sizes and alignments
are reported in bytes as well. Only while a struct is being built, the
type size may include an additional '+x' for the bits of a bit-field.

lint: support _Alignas and __attribute__((__aligned(4)))

lint: merge function call operators 'CALL' and 'ICALL'

lint: inline accessor macros for tnode_t

lint: inline accessor macros for type_t

lint: clean up comments, use typedefs

lint: internally store case label values in order of appearance

lint: remove unneeded checks for left and right operands

lint: use fewer struct keywords

lint: clean up string parsing and snprintb check

lint: make function call arguments directly accessible

Previously, the arguments of a function call expression were arranged in
a linear tree structure, from right to left. To allow easier access to
the arguments, store them in an array instead.

lint: remove excessive empty lines

lint: keep strings in their source representation

This allows further analysis depending on whether individual characters are
escaped as octal, hexadecimal or not at all.

lint: use standard buffer for storing string values

No functional change.

lint: do not remember content of wide string literals

The plain char literals are needed for checking printf/scanf format
strings; lint has no similar check for wide strings. These format
strings are checked by modern compilers, making this check less
relevant.

lint: rename symt_t to symbol_kind

It was confusing to have two kinds of "symbol type" (s_type and s_symt),
so rename all related identifiers to be more distinctive.

No functional change.

lint: clean up enum constants for designators

In intializers and offsetof, both struct and union members are handled
in the same way, thus there is no need to distinguish them.

lint: allow complex offsetof(type, member-designator)

Both GCC 11 and Clang 8 accept member-designators that are not
identifiers but designator sequences, such as in 'offsetof(struct stat,
st_atim.tv_sec)', so make lint accept them as well.

lint: remove redundant parentheses, braces and comments

Rename the functions for folding constant expressions, to make the
comments redundant.

lint: in declarations, replace tab with space

Previously, in some cases, the keywords 'const' or 'struct' were
followed by a tab, which doesn't make sense.

No functional change.

lint: re-wrap comments

No functional change.

lint: rename NOSCL to NO_SCL

For symmetry with NO_TSPEC. No functional change.

lint: remove preprocessor magic from definition of operators

No binary change.

lint: prevent invalid memory access when checking an expression

In check_expr_misc, the left and right operands of an expression were
accessed even in the case of CON (constant), STRING (string literal) and
NAME (identifier), which led to invalid values in pointer variables.
These invalid values were not used though, but technically they invoked
undefined behavior.

Precede each access to the operands with a check that the expression
indeed has operands, except in those cases where the operand is known to
have operands by only looking at the code of the current function.

lint: make diagnostics about ANSI C more international

lint: distinguish between arguments and parameters

lint: clear global variable 'dcs' after use

Having unnecessarily set members is confusing during debugging.

lint: only generate err-msgs.h in debug mode

lint: extract 'vararg' and 'prototype' flags from global 'dcs'

These flags are only relevant for parameter lists, so add a separate
type for it.

No functional change.

lint: work around a possible compiler error on arm and powerpc

lint: add detailed logging for finding memory allocation bugs

lint: clean up comments, add a test for the '?:' operator

lint: merge duplicate code for checking duplicate type qualifiers

lint: use separate types for parsing pointer types and type qualifiers

The documentation of the previous 'qual_ptr_t' was misleading, as that
type was used for other type qualifier lists as well, even if these were
not related to pointer types.

lint: _Thread_local is a storage class, not a type qualifier

lint: indent copyright lines consistently

lint: reduce code size for handling lint comments

lint: reject _Noreturn if it occurs in invalid places

C11 introduced _Noreturn as a function-specifier, not as a type
attribute. The latter may occur in more places.

lint: don't treat 'inline' as a storage class

The additional conflict in the grammar is in the same place as the other
conflicts, as T_SCLASS and T_FUNCTION_SPECIFIER are now separate tokens.

No functional change.

lint: update wording in diagnostic for C99

lint: merge duplicate code for getting the name of an operator

lint: add debug logging for symbol kinds in the parser

An identifier can refer to a variable, type, member, tag or label.
Switching between these namespaces is tightly coupled with the
evaluation order of the grammar rules.

lint: miscellaneous cleanup

lint: clean up redundant casts

lint: rename uppercase QUAD to LLONG

No binary change.

lint: add initial support for C23

Required by xsrc/external/mit/MesaLib.old, brw_eu_validate.c, which
initializes a struct using empty braces: 'return (struct string){};'.

lint: clean up variable names relating to structure padding

lint: rename 'quad' to 'signed int' or 'unsigned int'

No functional change.

lint: use unsigned int for struct alignment

This gets rid of 'unsigned short', which saved a few bytes of memory but
was inconvenient to deal with.

No functional change.

lint: clean up variable names

lint: clean up comments in lint1.h

lint: clean up names related to declaration levels

The previous prefix 'DK_' (declaration level kind) had a conflict with
the 'DK_' (designator kind) in init.c, so change the prefix to 'DLK_'.
The new name for dinfo_t is decl_level, which is more expressive.

No functional change.

lint: replace macro for unique identifiers with function

No functional change.

lint: clean up handling of declarations

No functional change.

lint: clean up member names of declaration levels

No functional change outside debug mode.

lint: use standard terminology for bit-field width

No functional change.

lint: enhance debug output for diagnostics

Only print the debug message if the diagnostic is active, which is
relevant for c99ism, c11ism and gnuism.

Print more details about the diagnostic or query.

lint: reduce memory allocations

The type val_t has the same size as the tn_s member in the same union.

No functional change.

lint: add query for comparing 'char' with plain integers

lint: miscellaneous clean-ups

No binary change, except for line numbers in assertions.

lint: rename type_t.t_str to t_sou

The name 't_str' could have meant 'string' or 'struct'. Since both
struct and union types have members, rename it to 't_sou'.

No functional change.

lint: use __printflike

lint: replace INTERNAL_ERROR with plain assert

lint: add support for the C11 type qualifier '_Atomic'

That keyword can be used as a type specifier as well, support for that
will be added later.

lint: use fewer abbreviations

No binary change except for line numbers in assertions in decl.c.

lint: remove custom memory allocator

Besides adding complexity, the custom memory allocator didn't invalidate
freed memory, which made it harder to find possible use-after-free bugs.

lint: add hyphen to adjective 'old-style'

lint: rename dcs manipulation functions to be clearer

No functional change.

lint: add additional queries that are not enabled by default

In the last 18 months, several lint warnings have been made adjusted to
allow common usage patterns. For example, lint no longer warns about a
constant condition in the statement 'do { ... } while (false)' (message
161), as this pattern is well-known in statement-like macros, making it
unlikely that the 'false' is a mistake. Another example is casts
between unequal pointer types (message 247) for a few well-known
patterns that are unlikely to be bugs.

Occasionally, it is useful to query the code for patterns or events that
would not justify a warning. These patterns are modeled as predefined
queries that can be selected individually, in addition to and
independently of the existing warnings and errors.

New queries can be added as needed, in the same way as new warnings.
Queries that are deemed no longer used can be deactivated in the same
way as warnings that are no longer used.

As long as none of the queries is enabled, they produce a minimal
overhead of querying a single global variable. Computations that are
more expensive than a few machine instructions should be guarded by
any_query_enabled.

https://mail-index.netbsd.org/source-changes-d/2022/06/28/msg013716.html

ok christos@

lint: move error handling code from main1.c to err.c

No functional change.

lint: rename olwarn and LWARN_BAD to be more expressive

No functional change.

lint: investigate why lint only warns about some constant conditions

Noticed in lex.c, in the macro kwdef, where lint complains about the
condition containing '||' but not about the conditions containing only
'>' or '=='.

lint: migrate gflag to allow_gcc

No functional change.

lint: fix assertion failure on duplicate qualifiers from __typeof__

lint: distinguish between storage class and declaration kind

These types overlap but are not the same.

No functional change.

lint: rename dinfo_t.d_offset to d_offset_in_bits

Most often, offsets are measured in bytes, so better embed the unit in
the variable name.

No functional change.

lint: extract is_member into separate function

No functional change.

lint: disambiguate sym_t.s_value

Having a single variable for 4 different purposes with different types
makes the code unnecessarily hard to follow.

No functional change.

lint: split CTCONST into BOOL_CONST and ENUM_CONST

Having a unified compile-time constant "storage class" made the code
more difficult to understand.

No functional change.

lint: inline member access macros for sym_t

Having the 'u.' explicitly in the code serves as a reminder that these
members are only defined under certain conditions.

No functional change.

lint: use appropriate alignment on both the host and target platform

lint: rename dinfo_t.d_next to d_enclosing

The name d_next gave the wrong impression that the declaration infos
would be independent of each other, but they are nested.

No functional change.

lint: merge duplicate code for handling plain and wide strings

No functional change. As before, the string literals "1" "2" "3" are
not concatenated from left to right, instead concatenation starts with
"23" and then proceeds to "123".

lint: unabbreviate two more members of sym_t

No functional change.

lint: remove unused enumeration details from symbol type

No functional change.

lint: unabbreviate some fields in sym_t

No functional change.

lint: clean up memory management for string buffers

There is no reason to duplicate all the work that is already done by the
memory allocator.

No functional change.

lint: clean up memory allocation

No functional change.

lint: rename ARG to OLD_STYLE_ARG

Pre-C90 argument declarations have been old for more than 30 years now,
so mention that fact in the constant name. This reduces potential
confusion with other occurrences of the words 'arg' or 'argument'.

No functional change.

lint: drop compatibility with C90

Since tools/README 1.5 from 2022-02-03, the tools no longer need to be
compatible with C90, they may now use C99 features. Lint had used
<stdbool.h> and snprintf already.

No functional change.

lint: don't try to trick mathematics by defining ZERO to a nonzero value

No binary change.

lint: clean up lex.c

Rename 'struct kwtab' to 'struct keyword' since a single keyword is not
a whole keyword table.

Sync comment for lex_name with reality: sbuf_t no longer contains the
hash value.

Remove redundant tests for EOF, as EOF is neither a space nor a digit
nor an xdigit.

No functional change.

lint: remove spaces around bit-field colon

As seen in /usr/share/misc/style.

No binary change.

lint: fix check for function calls in strict bool mode

Previously, if a function call occurred in the controlling expression,
its return type could be any scalar, not just bool. This was against
the goal of strict bool mode, which makes bool a separate and
incompabile type to all other types. For example, it would allow
controlling expressions like 'strcmp(a, b)' without the usual '!= 0',
but only if at least one of 'a' and 'b' came from a macro definition
from a system header.

The fix is that the decision of whether the type of the controlling
expression may be scalar is no longer based on the operand types but on
the main operator of the controlling expression.

lint: enter full C90 compatibility mode

The C99 comment in tree.c:3468 has been there since 2017-03-06, without
anyone complaining that their compiler would not handle it.

Strangely, running GCC 10.3.0 in '-std=c90' mode does not complain about
declarations after statements, '-Wdeclaration-after-statement' is needed
separately.

No functional change.

lint: allow [*] everywhere where [] and [integer] are allowed

It's a seldom used feature, but now it's at least consistent.

lint: remove unused function for generic messages

The function message_at is still used, for information about previous
occurrences of a symbol.

lint: fix a few lint warnings about type conversions

A simple 'unsigned int' is more than enough for representing the size of
a bit-field, as well as the maximum alignment of any type.

No functional change.

lint: un-abbreviate unsigned integer types

No functional change.

lint: expand macro in string concatenation

No functional change.

lint: inline msb

This reduces the binary size on x86_64 by about 500 bytes.

No functional change.

lint: merge duplicate code for binary operator

No functional change.

lint: save some memory

Before lint1.h 1.47 from 2021-01-02, adjacent bit-field struct members
shared storage. Restore that using smaller types.

No functional change.

lint: remove hash value from symbol buffer

Conceptually, a symbol buffer does not need to remember its hash value
since that belongs to the symbol table. This makes the code for the
symbol table simpler. The number of hash calculations increases by
about 5%, which is negligible.

No functional change.

lint: improve support for __int128_t and __uint128_t

For the .ln files, I chose the letter 'J' to represent the 128-bit
integer types since it is close to 'I' for int. The naming of 'L' for
'long' is obvious, but 'Q' for 64-bit integers is a quad-16-bit word,
which is an unusual measurement unit nowadays. One benefit of choosing
'J' is that the next letter, 'K' can then be used for 256-bit integer
types.

Support for 128-bit integer types is still very basic. Plus, it is only
supported on LP64 platforms, which means that lint cannot be
cross-compiled to check for an LP64 platform while running on an ILP32
platform.

lint: merge duplicate code for generating unqualified type

This is a preparation for fixing the wrong warnings in msg_115.c.

No functional change.

lint: rename cstk_t to control_statement

Rename the variables as well. Their previous name 'ci' was not easy to
understand, the 'i' may have meant 'stack item'. The new name 'cs'
simply means 'control statement'.

No functional change.

lint: remove a few unnecessary abbreviations

No functional change.

lint: make offset and alignment positive numbers

There's no use case for negative alignment or offsets in structures.

No functional change.

lint: rename grammar rule 'declaration' to 'declaration_or_error'

This prepares for merging the duplicate code from top_level_declaration.
The code coverage outside cgram.y is exactly the same as before.

No functional change.

lint: rename clrtyp/deftyp to begin_type/end_type

The abbreviations clr/def did not make it obvious that these two
functions or grammar rules form pairs.

No functional change.

lint: constify keyword in lexer

No functional change.

lint: rename type generic_association_types to generic_association

The word 'types' was misleading and unnecessary.

No functional change.

lint: rename dinfo_t.d_stralign to d_sou_align_in_bits

When talking about alignment, offset and size of a type, the measurement
unit must be mentioned in the variable name, especially when it differs
from the standard unit of measurement, which is a byte, not a bit.

No functional change.

lint: in strict bool mode, allow mixed types in generated C code

This allows flex lexers to be run through lint in strict bool mode.

lint: document lint1_type.t_is_enum

Enum types are subject to implicit conversions, as opposed to struct,
union, pointer and function types.

lint: rename pqinf_t to qual_ptr and clean up code

The 'inf' from the type name meant 'information' and was redundant. Each
object of that type represents a single pointer level, which made the
documentation about 'pointers' a bit confusing.

The members of struct qual_ptr are now in the canonical reading order,
which is 'const volatile pointer'.

No functional change.

lint: fix result type of _Generic expressions

lint: fix type of pqinf.p_pcnt

A counter that can either be 0 or 1 and is never incremented is not
really a counter, it's a flag.

No functional change.

lint: rename val_t.v_unsigned to avoid confusion

The name v_unsigned suggested that the value would be interpreted as
unsigned, which was wrong. Whether a value is signed or unsigned is
decided by v_tspec instead.

Revert the previous commit for boolen constants since their value is
already interpreted as unsigned, and there is no need for any warning
about differences between traditional C and ANSI C since the _Bool type
has only been added ten years later in C99.

The code for printing a tree node was also confused by this struct
member, even with its old name v_ansiu. That code will be fixed in a
follow-up commit.

No functional change.

lint: rename val_t.v_ansiu to v_unsigned

When lint was written in 1995, traditional C was still nearby since C90
had been around for only 5 years. 26 years later, almost all code
adheres to C90 or even C99 or C11, therefore "C90 or later" can safely
be assumed as the default.

No functional change.

lint: replace undefined behavior with assertion failure

Triggered by this malformed code:

struct{int;

lint: replace array access with function calls

First and foremost, the test d_c99_complex_split accessed the array
qlmasks out-of-bounds, with an index of 128 for the type 'double
_Complex'. This invoked undefined behavior since the maximum allowed
index was 64.

Replacing the raw array accesses with function calls allows for bounds
checks to catch these errors early.

Determining the value bits for a 'double _Complex' does not make sense
at all since it is not an integer type. This means that lint didn't
handle these types correctly for several years. Support for int128_t
has been added in inittyp.c 1.12 from 2018-09-07, support for _Complex
has been added in inittyp.c 1.9 from 2008-04-26.

Determining the value bits for an int128_t would make sense, but the
unit tests don't contain examples for this type since at the moment all
unit tests must produce the same results on 32-bit and 64-bit platforms,
and the 32-bit platforms don't support int128_t.

lint: warn about unreachable case labels for '&&'

See octeon_gmxreg.h 1.2 from 2020-06-18 for an example, where
RXN_RX_INBND_SPEED was cleaned up without adjusting the corresponding
code in octeon_gmx.c.

branches: 1.100.2;
lint: remove redundant CONSTCOND

In do-while-0 loops, these are no longer needed since tree.c 1.202 from
2021-01-31.

lint: rename parameter to diagnostic functions and macros

The first parameter is not just an arbitrary number, it's a message ID.

lint: align the member access macros for tnode_t

lint: add error_at, warning_at, message_at

Right now there are several places in the code that use the global
variable curr_pos for passing a parameter to the diagnostic functions.
That's not what global variables are for.

Make it easy for the code to migrate to the parameter-passing style.

No functional change.

lint: document wrong location information in diagnostics

lint: add support for C11-isms such as int[static 3]

lint: use distinct struct tags for type_t in lint1 and lint2

Having two similar but still different definitions of 'struct type' is
unnecessarily confusing. Exchange this confusion for 8 lines of
straight-forward preprocessing code.

lint: prepare renaming of 'struct type'

It's confusing to have the same struct tag in both lint1 and lint2, with
mostly the same members, but also some differences. Before actually
changing this, I reviewed all occurrences of the word 'type' in the
code.

No functional change.

lint: reduce memory usage

No functional change.

lint: rename mbl to memory_block

No functional change.

lint: rename LERROR to INTERNAL_ERROR

The '#ifndef' in tyname.c is meant to distinguish between lint1 and
lint2, it is not meant to be defined from anywhere outside the lint code
itself.

No functional change.

lint: rename members of struct control_statement to be more expressive

C99 does not define names for the head parts of the 'for' statements, it
just calls them clause-1, expression-2 and expression-3. Therefore the
rather abstract name 'expr3'.

No functional change.

lint: rename pushctrl and popctrl to be more expressive

While here, remove the magic number 0 that in this context means
"function body".

No functional change.

lint: fix reachability for constant controlling expression in for loop

lint: fix reachability computation in if statements

Previously, only loop statements were considered for reachability. This
ignored the possibility of an early return in an if statement, or
unreachable branches.

lint: rename c_rchif to c_reached_end_of_then

No functional change.

lint: rename c_cont to c_continue

No functional change.

lint: document the precise meaning of control_statement.c_break

No functional change.

lint: rename i_infinite to i_maybe_endless

Not every loop that has 'while (1)' is an endless loop. It may still
contain a 'return' somewhere.

lint: fix wrong 'falls off bottom' after return in do-while

lint: rename d_fargs, d_fdpos and d_fpsyms to be less abbreviated

No functional change.

lint: rename d_nedecl to d_nonempty_decl

No functional change.

lint: rename d_rdcsym to d_redeclared_symbol

No functional change.

lint: rename clst to case_labels

No functional change.

lint: document the struct for declarations more precisely

No functional change.

lint: rename in_bit to in_bits

No functional change.

lint: document the initialization of an object in more detail

This will help fixing the bugs that are currently demonstrated in
msg_168.c and d_struct_init_nested.c.

lint: clean up documentation of dinfo_t

No functional change.

lint: rename dinfo_t members to be more expressive

While here, sync redundant but diverging comments, split
multi-assignments and initialize the members in declaration order.

No functional change.

lint: rename 'blklev' to 'block_level'

No functional change.

lint: fix off-by-one error in 'case 3...5'

According to the GCC documentation[1], the high end of the range is
inclusive as well, which makes sense since otherwise there would be no
way of specifying a range that includes the maximum representable
number.

Since the range is not used at all in the code, none of the tests could
possibly fail.

[1] https://gcc.gnu.org/onlinedocs/gcc/Case-Ranges.html

No functional change.

lint: replace wrong comment with assertion

The broad type of a value is indeed stored in the value itself, in the
member v_tspec. For nodes that refer to this value, it is redundantly
stored, it always equals tn->tn_type->t_tspec.

After initialization, neither tn->tn_type nor val->v_tspec are modified.
This is not ensured by the compiler but has to be analyzed manually.

No functional change.

lint: rename is_nonzero to constant_is_nonzero

The new function name emphasizes that the given node must have the
operator CON.

No functional change.

lint: do not warn about constant expressions involving sizeof

These expressions are indeed constant for a specific platform, but on
another platform their value may change. This makes them unsuspicious
and legitimate for portable code.

Seen in rump_syscalls.c, as 'sizeof(int) > sizeof(register_t)'.

lint: change spelling of initialisation to initialization

That's the wording from the ISO C99 standard.

lint: rename storage class constants to be more expressive

No functional change.

lint: rename t_isenum and t_aincompl to be more expressive

No functional change.

lint: rename tenum_t and its members to be more expressive

lint: rename str_t and its members to be more expressive

No functional change.

lint: replace cryptic sym.s_rimpl with expressive name

No functional change.

lint: fix two wrong error messages in strict bool mode

The strict bool mode gets complicated because for system headers the
rules need to be relaxed since they cannot be changed easily, often not at all.

Still, if lint validates a program in strict bool mode, that program
must run with equal behavior regarding boolean expressions even on a
pre-C99 platform.

lint: clean up member names of control_structure and comments

lint: extend a few message comments

lint: replace integer constant expressions with true and false

LINTFLAGS=-gST make lint, with manual review.

The error messages from lint are all correct, they are not complete
though. The return value of a function returning bool may still be
compared to the integer 0.

lint: in strict bool mode, integer constants do not have type bool

Previously, lint1 allowed integer constants such as 0 and 1 to be used
as bool constants. This was only half-baked since after fixing all
error messages from that strict mode, there may still be integer
literals in the code that should be replaced with true or false. This
would stop a migration from int to bool in the middle, leaving
inconsistent code around.

To find the remaining type inconsistencies, treat integers and bool as
completely incompatible, even for compile time constants.

lint: replace 0 and 1 with false and true, where appropriate

Change in behavior: Passing the option -h exactly 4294967296 times or
any multiple thereof is no longer equivalent to passing it never at all,
it is now equivalent to passing it once. See main2.c, hflag++ for the
actual change.

Other than that, no functional change intended.

A very large portion of the code already conformed to the requirements
of the strict bool mode. The only missing thing was using the constant
literals false and true instead of 0 and 1. For sure there are some
integer literals left that can be converted. For now, all literals that
appeared in the form " = 0" or " = 1" have been replaced.

lint: merge duplicate code for non-zero detection

lint: fix typos and other minor stylistic issues

lint: rename cstk to cstmt

Most of the code that deals with control statements is only interested
in the innermost control statement, and not if that is a stack or not.
Therefore, emphasize that part in the variable name.

The member c_next was confusing since the "direction" of this "next
element" was ambiguous. In a sequence of if statements, the "next"
element could have equally been the following one, not the surrounding
one.

lint: rename t_ispacked to t_packed and d_ispacked to d_packed

It's shorter, and the other flags of the type or declaration also don't
have "is" in their names. Except for t_isenum, but that's because there
is a macro named t_enum that would interfere with that name.

lint: rename type.t_isfield to t_bitfield

lint: in DEBUG mode, verify printf parameters for messages

Since several years GCC validates printf-style strings, and there is no
reason not to let GCC do that work. This prevents bugs like the
segmentation fault that was fixed in tree.c 1.109 from 2021-01-01.

By default, lint is compiled with DEBUG off, but it's easy enough to
compile it in debug mode once in a while.

lint: fix lint warning 161 "constant in conditional context"

lint: use bool instead of u_int:1 in structures

Better late than never.

lint: un-export struct istk

lint: inline STRUCT_ASSIGN

This had only been necessary for some pre-C90 compilers.

lint: un-abbreviate s_dpos, s_spos and s_upos

lint: un-abbreviate s_field, s_keyw and s_xsym

lint: un-abbreviate parenthesized and _strg

lint: rename remaining _nxt members to _next

lint: rename more _nxt members to _next

lint: rename symt_t constants

There's no need to abbreviate them, furthermore FMOS was imprecise.

lint: rename s_nxt to s_next

lint: reduce verbosity of assertions

Having 2 lines of source code per assertion is too much, especially
since most of this code is redundant anyway. Extract the common code
and the additional negation into a simple function instead.

lint: rename istk_t.i_cnt to i_remaining

lint: fix typo in comments

lint: fix indentation and alignment that used space-tab

lint: spell check

lint1: remove unused t_field

Add __thread/tls_model attribute

branches: 1.30.14;
teach lint __attribute__((__unused__))

branches: 1.29.6;
typo in comment

only fill memory with junk if BLKDEBUG

branches: 1.27.4;
Allow linted comments to take an argument that defines which error to suppress.

rename enum_t to avoid rpc/types.h lossage.

branches: 1.25.2; 1.25.8;
Always use our own align macro and explain a bit more why this is bogus.

recognize struct __packed x { }; in addition to struct x { } __packed;

understand __attribute__((__packed__)) and __packed.

Ignore restrict in the contexts where const and volatile is allowed.
No validation for the use (e.g. that it is used on a pointer), but
enough to not stop valid C99 programs.

fix const and volatile printing in types.

preliminary _Complex support.
NB: Does not really understand type conversions between complex and doubles.

branches: 1.19.20;
in several comments:
implizit -> implicit
explizit -> explicit