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* [Bug regex/28170] New: attribute access (write_only, 4, 3) on regexec triggers a warning
@ 2021-08-02 19:57 msebor at gmail dot com
2021-08-13 21:54 ` [Bug regex/28170] " msebor at gmail dot com
0 siblings, 1 reply; 2+ messages in thread
From: msebor at gmail dot com @ 2021-08-02 19:57 UTC (permalink / raw)
To: glibc-bugs-regex
https://sourceware.org/bugzilla/show_bug.cgi?id=28170
Bug ID: 28170
Summary: attribute access (write_only, 4, 3) on regexec
triggers a warning
Product: glibc
Version: unspecified
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: regex
Assignee: unassigned at sourceware dot org
Reporter: msebor at gmail dot com
CC: drepper.fsp at gmail dot com
Target Milestone: ---
Commit 26492c0a14966c32c43cd6ca1d0dca5e62c6cfef
(https://sourceware.org/pipermail/glibc-cvs/2021q2/073049.html) adds attribute
access to a number of APIs, including the regexec function like so:
@@ -648,10 +655,12 @@ extern int regcomp (regex_t *_Restrict_ __preg,
extern int regexec (const regex_t *_Restrict_ __preg,
const char *_Restrict_ __String, size_t __nmatch,
regmatch_t __pmatch[_Restrict_arr_],
- int __eflags);
+ int __eflags)
+ __attr_access ((__write_only__, 4, 3));
The attribute was added here based on the POSIX description of the function
that describes the pmatch array referenced by it as write-only (at least
nothing I can find in POSIX says the function writes to it).
With a recent GCC 12 enhancement to detect read accesses to write-only objects
the presence of the attribute triggers the following warning:
regexec.c: In function ‘__regexec’:
regexec.c:204:13: warning: ‘*pmatch.rm_so’ is used uninitialized
[-Wuninitialized]
regexec.c:192:101: note: accessing argument 4 of a function declared with
attribute ‘access (write_only, 4, 3)’
The warning indicates that the attribute may not, in fact, appropriate for the
function when since it writes to the referenced object. The write takes place
when the REG_STARTEND bit (a Glibc extension) is set in flags.
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* [Bug regex/28170] attribute access (write_only, 4, 3) on regexec triggers a warning
2021-08-02 19:57 [Bug regex/28170] New: attribute access (write_only, 4, 3) on regexec triggers a warning msebor at gmail dot com
@ 2021-08-13 21:54 ` msebor at gmail dot com
0 siblings, 0 replies; 2+ messages in thread
From: msebor at gmail dot com @ 2021-08-13 21:54 UTC (permalink / raw)
To: glibc-bugs-regex
https://sourceware.org/bugzilla/show_bug.cgi?id=28170
--- Comment #1 from Martin Sebor <msebor at gmail dot com> ---
Patch: https://sourceware.org/pipermail/libc-alpha/2021-August/130137.html
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