manual: Mark perror as MT-unsafe and update check-safety.sh

The manual marked perror as MT-safe, but then listed a remark
indicating that it was unsafe because of a race between the function
and access to stderr.  The function is indeed MT-unsafe because
of the unlocked access to stderr internals and bug 32730 has been
filed to address this issue.

The script manual/check-safety.sh should have caught this issue,
but a missed escaping of "?" along with searching of all inputs
again via "$@" resulted in a non-functional regexp.

In order to avoid regressions we also update check-safety.sh.

The script manual/check-safety.sh is updated in the following ways:

 * The MT-unsafe remarks in MT-safe context check is fixed.
   - It now detects the perror safety note mistake.

 * Comments updated indicating that we allow MT context marks
   to count for other contexts if they are related.
   - This is why commit ad9c4c5361
     failed and the failure is now understood as expected.

 * All checks now have verbose output.

 * Back reference based duplicate checks are removed.
   - They are too complex and don't cover all cases.

No regressions on x86_64.

manual/check-safety.sh

@@ -22,7 +22,7 @@
 # in proper order (mt then as then ac), that remarks appear within
 # corresponding sections (mt within mt, etc), that unsafety always has
 # an explicit reason and when there's a reason for unsafety it's not
-# safe, and that there aren't duplicates remarks.
+# safe.
 
 
 success=:
@@ -37,10 +37,15 @@ test $# != 0 || set *.texi
 
 # Check that all safety remarks have entries for all of MT, AS and AC,
 # in this order, with an optional prelim note before them.
+ret=true
 grep -n '^@safety' "$@" |
 grep -v ':@safety{\(@prelim{}\)\?@mt\(un\)\?safe{.*}'\
 '@as\(un\)\?safe{.*}@ac\(un\)\?safe{.*}}' &&
-success=false
+ret=false
+if ! $ret; then
+    echo "FAIL: #1 - Missing context in @safety macro."
+    success=false
+fi
 
 # Check that @mt-started notes appear within @mtsafe or @mtunsafe,
 # that @as-started notes appear within @assafe or @asunsafe, and that
@@ -49,6 +54,7 @@ success=false
 # unsafe), but let @mt have as, ac or asc before [su], and let @as
 # have a c (for cancel) before [su].  Also make sure blanks separate
 # each of the annotations.
+ret=true
 grep -n '^@safety' "$@" |
 grep -v ':@safety{\(@prelim{}\)\?'\
 '@mt\(un\)\?safe{\(@mt\(asc\?\|ac\)\?[su][^ ]*}\)\?'\
@@ -57,68 +63,98 @@ grep -v ':@safety{\(@prelim{}\)\?'\
 '\( @asc\?[su][^ ]*}\)*}'\
 '@ac\(un\)\?safe{\(@ac[su][^ ]*}\)\?'\
 '\( @ac[su][^ ]*}\)*}}' &&
-success=false
+ret=false
+if ! $ret; then
+    echo "FAIL: #2 - Incorrect @safety macro formatting."
+    success=false
+fi
 
 # Make sure safety lines marked as @mtsafe do not contain any
 # MT-Unsafe remark; that would be @mtu, but there could be as, ac or
 # asc between mt and u.
+ret=true
 grep -n '^@safety.*@mtsafe' "$@" |
-grep '@mt\(asc\?\|ac\)?u' "$@" &&
-success=false
+grep '@mt\(asc\?\|ac\)\?u' &&
+ret=false
+if ! $ret; then
+    echo "FAIL: #3 - MT context contains remarks when it should not."
+    success=false
+fi
 
 # Make sure @mtunsafe lines contain at least one @mtu remark (with
 # optional as, ac or asc between mt and u).
+ret=true
 grep -n '^@safety.*@mtunsafe' "$@" |
 grep -v '@mtunsafe{.*@mt\(asc\?\|ac\)\?u' &&
-success=false
+ret=false
+if ! $ret; then
+    echo "FAIL: #4 - MT context lacks at least one remark."
+    success=false
+fi
 
 # Make sure safety lines marked as @assafe do not contain any AS-Unsafe
 # remark, which could be @asu or @mtasu note (with an optional c
 # between as and u in both cases).
+ret=true
 grep -n '^@safety.*@assafe' "$@" |
 grep '@\(mt\)\?asc\?u' &&
-success=false
+ret=false
+if ! $ret; then
+    echo "FAIL: #5 - AS context contains remarks when it should not."
+    success=false
+fi
 
 # Make sure @asunsafe lines contain at least one @asu remark (which
-# could be @ascu, or @mtasu or even @mtascu).
+# could be @ascu, or @mtasu or even @mtascu).  We allow the AS safety
+# remark from an earlier MT-unsafe to count towards such a remark
+# e.g. @mtunsafe{@mtasurace{:LogMask}}@asunsafe{}@acsafe{} is allowed.
+ret=true
 grep -n '^@safety.*@asunsafe' "$@" |
 grep -v '@mtasc\?u.*@asunsafe\|@asunsafe{.*@asc\?u' &&
-success=false
+ret=false
+if ! $ret; then
+    echo "FAIL: #6 - AS unsafe context lacks at least one remark."
+    success=false
+fi
 
 # Make sure safety lines marked as @acsafe do not contain any
 # AC-Unsafe remark, which could be @acu, @ascu or even @mtacu or
 # @mtascu.
+ret=true
 grep -n '^@safety.*@acsafe' "$@" |
 grep '@\(mt\)\?as\?cu' &&
-success=false
+ret=false
+if ! $ret; then
+    echo "FAIL: #7 - AC context contains remarks when it should not."
+    success=false
+fi
 
 # Make sure @acunsafe lines contain at least one @acu remark (possibly
 # implied by @ascu, @mtacu or @mtascu).
+ret=true
 grep -n '^@safety.*@acunsafe' "$@" |
 grep -v '@\(mtas\?\|as\)cu.*@acunsafe\|@acunsafe{.*@acu' &&
-success=false
-
-# Make sure there aren't duplicate remarks in the same safety note.
-grep -n '^@safety' "$@" |
-grep '[^:]\(@\(mt\|a[sc]\)[^ {]*{[^ ]*}\).*[^:]\1' &&
-success=false
+ret=false
+if ! $ret; then
+    echo "FAIL: #8 - AC unsafe context lacks at least one remark."
+    success=false
+fi
 
 # Check that comments containing safety remarks do not contain {}s,
 # that all @mt remarks appear before @as remarks, that in turn appear
 # before @ac remarks, all properly blank-separated, and that an
 # optional comment about exclusions is between []s at the end of the
 # line.
+ret=true
 grep -n '^@c \+[^@ ]\+\( dup\)\?'\
 '\( @\(mt\|a[sc]\)[^ ]*\)*\( \[.*]\)\?$' "$@" |
 grep -v ':@c *[^@{}]*\( @mt[^ {}]*\)*'\
 '\( @as[^ {}]*\)*\( @ac[^ {}]*\)*\( \[.*]\)\?$' &&
-success=false
-
-# Check that comments containing safety remarks do not contain
-# duplicate remarks.
-grep -n '^@c \+[^@ ]\+\( dup\)\?'\
-'\( @\(mt\|a[sc]\)[^ ]*\)*\( \[.*]\)\?$' "$@" |
-grep '[^:]\(@\(mt\|a[sc]\)[^ ]*\) \(.*[^:]\)\?\1\($\| \)' &&
-success=false
+ret=false
+if ! $ret; then
+    echo "FAIL: #9 - Comment safety note ordering, brackets, or"\
+	 "exclusions are incorrect."
+    success=false
+fi
 
 $success

manual/errno.texi

@@ -1256,7 +1256,7 @@ It is a POSIX extension.
 
 @deftypefun void perror (const char *@var{message})
 @standards{ISO, stdio.h}
-@safety{@prelim{}@mtsafe{@mtasurace{:stderr}}@asunsafe{@asucorrupt{} @ascuintl{} @ascuheap{} @asulock{}}@acunsafe{@acucorrupt{} @aculock{} @acsmem{} @acsfd{}}}
+@safety{@prelim{}@mtunsafe{@mtasurace{:stderr}}@asunsafe{@asucorrupt{} @ascuintl{} @ascuheap{} @asulock{}}@acunsafe{@acucorrupt{} @aculock{} @acsmem{} @acsfd{}}}
 @c Besides strerror_r's and some of fprintf's issues, if stderr is not
 @c oriented yet, create a new stream with a dup of stderr's fd and write
 @c to that instead of stderr, to avoid orienting it.