Implement the man(7) .MR macro, a 2023 GNU extension.
The syntax and semantics is almost identical to mdoc(7) .Xr.

This will be needed for reading the groff manual pages once our port
will be updated to 1.23, and the Linux Manual Pages Project is also
determined to start using it sooner or later. I did not advocate for
this new macro, but since we want to remain able to read all manual
pages found in the wild, there is little choice but to support it.
At least it is easy to do, they basically copied .Xr.

The .AT, .DT, and .UC macros are allowed inside next-line scope
and never produce output at the place of their invocation.

Minibugs found while investigating unrelated afl(1) reports from tb@.

In groff, when the .SY block macro occurs in no-fill mode,
the output line gets broken after the head. Do the same.

test new MT macro

more tests regarding empty header lines

better error reporting regarding .OP .RS .UR .TH arguments

new regression tests collected during recent work

Infrastructure for regression tests of mandoc messages.
Even though messages are not going to be as stable as formatted output,
that is, even though the *.out_lint files are expected to change now and then,
from now on, i want to be able to catch unintended changes in messages.

Implement the .UR/.UE block (uniform resource identifier) introduced in the
man-ext macros by Eric S. Raymond, enabled by default in groff_man(7).
Usual disclaimer: You don't write new man(7) code, so you are not going
to use these, either.
Improves e.g. the bzr(1) and etherape(1) manuals.
Thanks to naddy@ for bringing these to my attention.

Test paragraph distance (.PD) implementation;
related to man_term.c rev. 1.88, man_validate.c rev. 1.56.

enable more tests, some were forgotten along the way

Translate blank input lines to .sp just like in mdoc(7),
and ignore .sp after .PP. This fixes vertical spacing
for blank lines after .PP and for .sp after .PP.

multiple fixes to -Tascii .HP rendering:
* do not add an excessive blank line before the block
* in literal mode, start a new line after the tag

getting this to work requires some general (print_man_node) fixes:
* in literal mode, break the output line at the end of each
input line, not just after those input lines ending in text
* but don't break it when there was no output on the line
* and adjust the margins after the .HP tag

these general fixes require an adjustment to -Tascii .TP rendering:
* set up NOBREAK mode before the body, not after the head

finally, based on all this, implement -Tman .Bl -hang in terms of .HP

Add a test for RS breaking some other block.
Unfortunately, the code triggering the assert fixed in man_macro.c rev. 1.37
must be commented out because groff misformats the invalid input
so badly that imitating it really makes no sense.

Minimal implementation of .EX and .EE for GNU compatibility.
Do not use this, it is not portable and only defined in esr's man-ext.
For example, sox(1) wants these macros.

Complete overhaul of the mandoc(1) test suite.
* Test the recently introduced -Tman output mode, too.
* Specify date and OS arguments in all tests.
* Remove the kludge of sed(1)ing away the page footer lines.
* New make(1) variables SKIP_TMAN, SKIP_GROFF.
* Drop obsolete, clumsy make(1) variable GROFF_TARGETS.
* Delete obsolete mdoc/Bl/E*.sh error reporting tests.
* Silence char/N/basic.
* New targets:
- ascii, ascii-clean - to run -Tascii tests only
- tman, tman-clean - to run the new -Tman tests only
- obj-clean - maintainer only, needed before groff-clean and groff
- groff-clean - maintainer only, affects checked-in files

Theo reported that make cleandir deleted too much, triggering this cleanup:

Since quite some time, the groff output files are checked into CVS.
* thus, no longer provide a "groff-clean" target to delete them
* from official targets, no longer call the "groff" target generating them
* do not reimplement "clean" and "cleandir", simply use the official targets

another test found in yet another tree;
no more working, but uncommitted tests lying around now

Refrain from throwing fatal errors for
* .br .sp .nf .fi .na with arguments - just skip the arguments
* .TH lacking arguments - use empty strings instead like groff
* .TH with excessive arguments - skip those
Reminded by Joerg Sonnenberger, ok kristaps@.

test font-alternating blocks in literal context;
related to usr.bin/mandoc/man_term.c rev. 1.51

Multiple man(7) .IP and .TP fixes started during p2k10:

Affecting both -Tascii and -Thtml:
* The .IP HEAD uses the second argument as the width, not the last one.
* Only print the first .IP HEAD argument, not all but the last.

Affecting only -Tascii:
* The .IP and .TP HEADs must be printed without literal mode,
but literal mode must be restored afterwards.
* After the .IP and .TP bodies, we only want term_newln(), not
term_flushln(), or we would get two blank lines in literal mode.
* The .TP HEAD does not use TWOSPACE, just like .IP doesn't either.
* In literal mode, clear NOLPAD after each line, or subsequent lines
would get no indentation whatsoever.

Affecting only -Thtml:
* Only print next-line .TP children, instead of all but the first.

OK kristaps@ on the -Tascii part; and:
"Can you work this into man_html.c, too?"

The .AT, .DT, and .UC macros are allowed inside next-line scope
and never produce output at the place of their invocation.

Minibugs found while investigating unrelated afl(1) reports from tb@.

In groff, when the .SY block macro occurs in no-fill mode,
the output line gets broken after the head. Do the same.

test new MT macro

more tests regarding empty header lines

better error reporting regarding .OP .RS .UR .TH arguments

new regression tests collected during recent work

Infrastructure for regression tests of mandoc messages.
Even though messages are not going to be as stable as formatted output,
that is, even though the *.out_lint files are expected to change now and then,
from now on, i want to be able to catch unintended changes in messages.

Implement the .UR/.UE block (uniform resource identifier) introduced in the
man-ext macros by Eric S. Raymond, enabled by default in groff_man(7).
Usual disclaimer: You don't write new man(7) code, so you are not going
to use these, either.
Improves e.g. the bzr(1) and etherape(1) manuals.
Thanks to naddy@ for bringing these to my attention.

Test paragraph distance (.PD) implementation;
related to man_term.c rev. 1.88, man_validate.c rev. 1.56.

enable more tests, some were forgotten along the way

Translate blank input lines to .sp just like in mdoc(7),
and ignore .sp after .PP. This fixes vertical spacing
for blank lines after .PP and for .sp after .PP.

multiple fixes to -Tascii .HP rendering:
* do not add an excessive blank line before the block
* in literal mode, start a new line after the tag

getting this to work requires some general (print_man_node) fixes:
* in literal mode, break the output line at the end of each
input line, not just after those input lines ending in text
* but don't break it when there was no output on the line
* and adjust the margins after the .HP tag

these general fixes require an adjustment to -Tascii .TP rendering:
* set up NOBREAK mode before the body, not after the head

finally, based on all this, implement -Tman .Bl -hang in terms of .HP

Add a test for RS breaking some other block.
Unfortunately, the code triggering the assert fixed in man_macro.c rev. 1.37
must be commented out because groff misformats the invalid input
so badly that imitating it really makes no sense.

Minimal implementation of .EX and .EE for GNU compatibility.
Do not use this, it is not portable and only defined in esr's man-ext.
For example, sox(1) wants these macros.

Complete overhaul of the mandoc(1) test suite.
* Test the recently introduced -Tman output mode, too.
* Specify date and OS arguments in all tests.
* Remove the kludge of sed(1)ing away the page footer lines.
* New make(1) variables SKIP_TMAN, SKIP_GROFF.
* Drop obsolete, clumsy make(1) variable GROFF_TARGETS.
* Delete obsolete mdoc/Bl/E*.sh error reporting tests.
* Silence char/N/basic.
* New targets:
- ascii, ascii-clean - to run -Tascii tests only
- tman, tman-clean - to run the new -Tman tests only
- obj-clean - maintainer only, needed before groff-clean and groff
- groff-clean - maintainer only, affects checked-in files

Theo reported that make cleandir deleted too much, triggering this cleanup:

Since quite some time, the groff output files are checked into CVS.
* thus, no longer provide a "groff-clean" target to delete them
* from official targets, no longer call the "groff" target generating them
* do not reimplement "clean" and "cleandir", simply use the official targets

another test found in yet another tree;
no more working, but uncommitted tests lying around now

Refrain from throwing fatal errors for
* .br .sp .nf .fi .na with arguments - just skip the arguments
* .TH lacking arguments - use empty strings instead like groff
* .TH with excessive arguments - skip those
Reminded by Joerg Sonnenberger, ok kristaps@.

test font-alternating blocks in literal context;
related to usr.bin/mandoc/man_term.c rev. 1.51

Multiple man(7) .IP and .TP fixes started during p2k10:

Affecting both -Tascii and -Thtml:
* The .IP HEAD uses the second argument as the width, not the last one.
* Only print the first .IP HEAD argument, not all but the last.

Affecting only -Tascii:
* The .IP and .TP HEADs must be printed without literal mode,
but literal mode must be restored afterwards.
* After the .IP and .TP bodies, we only want term_newln(), not
term_flushln(), or we would get two blank lines in literal mode.
* The .TP HEAD does not use TWOSPACE, just like .IP doesn't either.
* In literal mode, clear NOLPAD after each line, or subsequent lines
would get no indentation whatsoever.

Affecting only -Thtml:
* Only print next-line .TP children, instead of all but the first.

OK kristaps@ on the -Tascii part; and:
"Can you work this into man_html.c, too?"

In groff, when the .SY block macro occurs in no-fill mode,
the output line gets broken after the head. Do the same.

test new MT macro

more tests regarding empty header lines

better error reporting regarding .OP .RS .UR .TH arguments

new regression tests collected during recent work

Infrastructure for regression tests of mandoc messages.
Even though messages are not going to be as stable as formatted output,
that is, even though the *.out_lint files are expected to change now and then,
from now on, i want to be able to catch unintended changes in messages.

Implement the .UR/.UE block (uniform resource identifier) introduced in the
man-ext macros by Eric S. Raymond, enabled by default in groff_man(7).
Usual disclaimer: You don't write new man(7) code, so you are not going
to use these, either.
Improves e.g. the bzr(1) and etherape(1) manuals.
Thanks to naddy@ for bringing these to my attention.

Test paragraph distance (.PD) implementation;
related to man_term.c rev. 1.88, man_validate.c rev. 1.56.

enable more tests, some were forgotten along the way

Translate blank input lines to .sp just like in mdoc(7),
and ignore .sp after .PP. This fixes vertical spacing
for blank lines after .PP and for .sp after .PP.

multiple fixes to -Tascii .HP rendering:
* do not add an excessive blank line before the block
* in literal mode, start a new line after the tag

getting this to work requires some general (print_man_node) fixes:
* in literal mode, break the output line at the end of each
input line, not just after those input lines ending in text
* but don't break it when there was no output on the line
* and adjust the margins after the .HP tag

these general fixes require an adjustment to -Tascii .TP rendering:
* set up NOBREAK mode before the body, not after the head

finally, based on all this, implement -Tman .Bl -hang in terms of .HP

Add a test for RS breaking some other block.
Unfortunately, the code triggering the assert fixed in man_macro.c rev. 1.37
must be commented out because groff misformats the invalid input
so badly that imitating it really makes no sense.

Minimal implementation of .EX and .EE for GNU compatibility.
Do not use this, it is not portable and only defined in esr's man-ext.
For example, sox(1) wants these macros.

Complete overhaul of the mandoc(1) test suite.
* Test the recently introduced -Tman output mode, too.
* Specify date and OS arguments in all tests.
* Remove the kludge of sed(1)ing away the page footer lines.
* New make(1) variables SKIP_TMAN, SKIP_GROFF.
* Drop obsolete, clumsy make(1) variable GROFF_TARGETS.
* Delete obsolete mdoc/Bl/E*.sh error reporting tests.
* Silence char/N/basic.
* New targets:
- ascii, ascii-clean - to run -Tascii tests only
- tman, tman-clean - to run the new -Tman tests only
- obj-clean - maintainer only, needed before groff-clean and groff
- groff-clean - maintainer only, affects checked-in files

Theo reported that make cleandir deleted too much, triggering this cleanup:

Since quite some time, the groff output files are checked into CVS.
* thus, no longer provide a "groff-clean" target to delete them
* from official targets, no longer call the "groff" target generating them
* do not reimplement "clean" and "cleandir", simply use the official targets

another test found in yet another tree;
no more working, but uncommitted tests lying around now

Refrain from throwing fatal errors for
* .br .sp .nf .fi .na with arguments - just skip the arguments
* .TH lacking arguments - use empty strings instead like groff
* .TH with excessive arguments - skip those
Reminded by Joerg Sonnenberger, ok kristaps@.

test font-alternating blocks in literal context;
related to usr.bin/mandoc/man_term.c rev. 1.51

Multiple man(7) .IP and .TP fixes started during p2k10:

Affecting both -Tascii and -Thtml:
* The .IP HEAD uses the second argument as the width, not the last one.
* Only print the first .IP HEAD argument, not all but the last.

Affecting only -Tascii:
* The .IP and .TP HEADs must be printed without literal mode,
but literal mode must be restored afterwards.
* After the .IP and .TP bodies, we only want term_newln(), not
term_flushln(), or we would get two blank lines in literal mode.
* The .TP HEAD does not use TWOSPACE, just like .IP doesn't either.
* In literal mode, clear NOLPAD after each line, or subsequent lines
would get no indentation whatsoever.

Affecting only -Thtml:
* Only print next-line .TP children, instead of all but the first.

OK kristaps@ on the -Tascii part; and:
"Can you work this into man_html.c, too?"

test new MT macro

more tests regarding empty header lines

better error reporting regarding .OP .RS .UR .TH arguments

new regression tests collected during recent work

Infrastructure for regression tests of mandoc messages.
Even though messages are not going to be as stable as formatted output,
that is, even though the *.out_lint files are expected to change now and then,
from now on, i want to be able to catch unintended changes in messages.

Implement the .UR/.UE block (uniform resource identifier) introduced in the
man-ext macros by Eric S. Raymond, enabled by default in groff_man(7).
Usual disclaimer: You don't write new man(7) code, so you are not going
to use these, either.
Improves e.g. the bzr(1) and etherape(1) manuals.
Thanks to naddy@ for bringing these to my attention.

Test paragraph distance (.PD) implementation;
related to man_term.c rev. 1.88, man_validate.c rev. 1.56.

enable more tests, some were forgotten along the way

Translate blank input lines to .sp just like in mdoc(7),
and ignore .sp after .PP. This fixes vertical spacing
for blank lines after .PP and for .sp after .PP.

multiple fixes to -Tascii .HP rendering:
* do not add an excessive blank line before the block
* in literal mode, start a new line after the tag

getting this to work requires some general (print_man_node) fixes:
* in literal mode, break the output line at the end of each
input line, not just after those input lines ending in text
* but don't break it when there was no output on the line
* and adjust the margins after the .HP tag

these general fixes require an adjustment to -Tascii .TP rendering:
* set up NOBREAK mode before the body, not after the head

finally, based on all this, implement -Tman .Bl -hang in terms of .HP

Add a test for RS breaking some other block.
Unfortunately, the code triggering the assert fixed in man_macro.c rev. 1.37
must be commented out because groff misformats the invalid input
so badly that imitating it really makes no sense.

Minimal implementation of .EX and .EE for GNU compatibility.
Do not use this, it is not portable and only defined in esr's man-ext.
For example, sox(1) wants these macros.

Complete overhaul of the mandoc(1) test suite.
* Test the recently introduced -Tman output mode, too.
* Specify date and OS arguments in all tests.
* Remove the kludge of sed(1)ing away the page footer lines.
* New make(1) variables SKIP_TMAN, SKIP_GROFF.
* Drop obsolete, clumsy make(1) variable GROFF_TARGETS.
* Delete obsolete mdoc/Bl/E*.sh error reporting tests.
* Silence char/N/basic.
* New targets:
- ascii, ascii-clean - to run -Tascii tests only
- tman, tman-clean - to run the new -Tman tests only
- obj-clean - maintainer only, needed before groff-clean and groff
- groff-clean - maintainer only, affects checked-in files

Theo reported that make cleandir deleted too much, triggering this cleanup:

Since quite some time, the groff output files are checked into CVS.
* thus, no longer provide a "groff-clean" target to delete them
* from official targets, no longer call the "groff" target generating them
* do not reimplement "clean" and "cleandir", simply use the official targets

another test found in yet another tree;
no more working, but uncommitted tests lying around now

Refrain from throwing fatal errors for
* .br .sp .nf .fi .na with arguments - just skip the arguments
* .TH lacking arguments - use empty strings instead like groff
* .TH with excessive arguments - skip those
Reminded by Joerg Sonnenberger, ok kristaps@.

test font-alternating blocks in literal context;
related to usr.bin/mandoc/man_term.c rev. 1.51

Multiple man(7) .IP and .TP fixes started during p2k10:

Affecting both -Tascii and -Thtml:
* The .IP HEAD uses the second argument as the width, not the last one.
* Only print the first .IP HEAD argument, not all but the last.

Affecting only -Tascii:
* The .IP and .TP HEADs must be printed without literal mode,
but literal mode must be restored afterwards.
* After the .IP and .TP bodies, we only want term_newln(), not
term_flushln(), or we would get two blank lines in literal mode.
* The .TP HEAD does not use TWOSPACE, just like .IP doesn't either.
* In literal mode, clear NOLPAD after each line, or subsequent lines
would get no indentation whatsoever.

Affecting only -Thtml:
* Only print next-line .TP children, instead of all but the first.

OK kristaps@ on the -Tascii part; and:
"Can you work this into man_html.c, too?"