lint: warn about extern declarations outside headers

https://mail-index.netbsd.org/tech-userlevel/2023/03/15/msg013727.html

tests/lint: document how compilers promote bit-fields

tests/lint: investigate how compilers interpret bit-fields

tests/lint: expect complete messages in feature tests

Previously, the tests contained many comments like /* expect: 123 */,
which were useless to a casual reader since nobody is expected to learn
lint's message IDs by heart. Replace these with the complete
diagnostics, to show what lint is complaining about.

The tests named msg_*.c have been left unmodified since they mention the
full message text in their header comment.

No functional change.

lint: fix assertion failure when promoting a bit-field larger than int

tests/lint: demonstrate assertion failure "len == size_in_bits(INT)"

Seen on sparc64 in hdtoa.c:341 since sparc64 is one of the platforms
that has 128-bit long double and defines struct ieee_ext.ext_frach:48
based on uint64_t, which is a GCC extension. Plain C99 only allows
_Bool, signed int and unsigned int as base type for bit-fields.

lint: allow large integer types for bit-fields in GCC mode

These types are explicitly allowed by GCC.

I'm not sure which of the flags -g and -p should be stronger. That is,
if both -g and -p are given, should 'unsigned char' be allowed as a
bit-field type since -g would allow it, or should it be warned about
since -p warns about it? For now, continue to warn about these.

tests/lint: fix test for GCC bit-field types

The whole purpose of this test is to try the message about invalid
bit-field types in GCC mode. Therefore, use the default lint1-flags
that include -g.

tests/lint: add test for bit-field types in GCC mode

tests/lint: document how compilers promote bit-fields

tests/lint: investigate how compilers interpret bit-fields

tests/lint: expect complete messages in feature tests

Previously, the tests contained many comments like /* expect: 123 */,
which were useless to a casual reader since nobody is expected to learn
lint's message IDs by heart. Replace these with the complete
diagnostics, to show what lint is complaining about.

The tests named msg_*.c have been left unmodified since they mention the
full message text in their header comment.

No functional change.

lint: fix assertion failure when promoting a bit-field larger than int

tests/lint: demonstrate assertion failure "len == size_in_bits(INT)"

Seen on sparc64 in hdtoa.c:341 since sparc64 is one of the platforms
that has 128-bit long double and defines struct ieee_ext.ext_frach:48
based on uint64_t, which is a GCC extension. Plain C99 only allows
_Bool, signed int and unsigned int as base type for bit-fields.

lint: allow large integer types for bit-fields in GCC mode

These types are explicitly allowed by GCC.

I'm not sure which of the flags -g and -p should be stronger. That is,
if both -g and -p are given, should 'unsigned char' be allowed as a
bit-field type since -g would allow it, or should it be warned about
since -p warns about it? For now, continue to warn about these.

tests/lint: fix test for GCC bit-field types

The whole purpose of this test is to try the message about invalid
bit-field types in GCC mode. Therefore, use the default lint1-flags
that include -g.

tests/lint: add test for bit-field types in GCC mode

tests/lint: expect complete messages in feature tests

Previously, the tests contained many comments like /* expect: 123 */,
which were useless to a casual reader since nobody is expected to learn
lint's message IDs by heart. Replace these with the complete
diagnostics, to show what lint is complaining about.

The tests named msg_*.c have been left unmodified since they mention the
full message text in their header comment.

No functional change.

lint: fix assertion failure when promoting a bit-field larger than int

tests/lint: demonstrate assertion failure "len == size_in_bits(INT)"

Seen on sparc64 in hdtoa.c:341 since sparc64 is one of the platforms
that has 128-bit long double and defines struct ieee_ext.ext_frach:48
based on uint64_t, which is a GCC extension. Plain C99 only allows
_Bool, signed int and unsigned int as base type for bit-fields.

lint: allow large integer types for bit-fields in GCC mode

These types are explicitly allowed by GCC.

I'm not sure which of the flags -g and -p should be stronger. That is,
if both -g and -p are given, should 'unsigned char' be allowed as a
bit-field type since -g would allow it, or should it be warned about
since -p warns about it? For now, continue to warn about these.

tests/lint: fix test for GCC bit-field types

The whole purpose of this test is to try the message about invalid
bit-field types in GCC mode. Therefore, use the default lint1-flags
that include -g.

tests/lint: add test for bit-field types in GCC mode

lint: fix assertion failure when promoting a bit-field larger than int

tests/lint: demonstrate assertion failure "len == size_in_bits(INT)"

Seen on sparc64 in hdtoa.c:341 since sparc64 is one of the platforms
that has 128-bit long double and defines struct ieee_ext.ext_frach:48
based on uint64_t, which is a GCC extension. Plain C99 only allows
_Bool, signed int and unsigned int as base type for bit-fields.

lint: allow large integer types for bit-fields in GCC mode

These types are explicitly allowed by GCC.

I'm not sure which of the flags -g and -p should be stronger. That is,
if both -g and -p are given, should 'unsigned char' be allowed as a
bit-field type since -g would allow it, or should it be warned about
since -p warns about it? For now, continue to warn about these.

tests/lint: fix test for GCC bit-field types

The whole purpose of this test is to try the message about invalid
bit-field types in GCC mode. Therefore, use the default lint1-flags
that include -g.

tests/lint: add test for bit-field types in GCC mode

lint: allow large integer types for bit-fields in GCC mode

These types are explicitly allowed by GCC.

I'm not sure which of the flags -g and -p should be stronger. That is,
if both -g and -p are given, should 'unsigned char' be allowed as a
bit-field type since -g would allow it, or should it be warned about
since -p warns about it? For now, continue to warn about these.

tests/lint: fix test for GCC bit-field types

The whole purpose of this test is to try the message about invalid
bit-field types in GCC mode. Therefore, use the default lint1-flags
that include -g.

tests/lint: add test for bit-field types in GCC mode