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* [Bug c/95445] New: diagnose incompatible calls to functions declared without prototype
@ 2020-05-30 22:32 msebor at gcc dot gnu.org
2020-05-30 22:32 ` [Bug c/95445] " msebor at gcc dot gnu.org
` (3 more replies)
0 siblings, 4 replies; 5+ messages in thread
From: msebor at gcc dot gnu.org @ 2020-05-30 22:32 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95445
Bug ID: 95445
Summary: diagnose incompatible calls to functions declared
without prototype
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: msebor at gcc dot gnu.org
Target Milestone: ---
GCC silently accepts calls to built-in functions declared without a prototype
as long as the arguments match the expected types (based on the prototype
hardcoded into GCC), but issues warnings for calls where the arguments don't
match.
But GCC makes no attempt to make sure that in calls to other (i.e.,
non-built-in) functions declared without prototype provided arguments have the
same type across all the calls. Diagnosing mismatches as suggested in the
comments below would help detect bugs caused by their incompatibily.
This enhancement is different from pr92212 which is about calls to K&R
functions defined in the same translation unit.
$ cat x.c && gcc -O2 -S -Wall x.c
char* strchr ();
char* f0 (const char *s)
{
return strchr (s, 'x'); // no warning (okay)
}
char* f1 (const char *s)
{
return strchr (s, "y"); // warning (good)
}
void g ();
void h (void)
{
g (1); // (presumably) okay, f's type is 'void (int)'
g ("foo"); // should be diagnosed
g (1, "bar"); // ditto
}
x.c: In function ‘f1’:
x.c:10:21: warning: passing argument 2 of ‘strchr’ makes integer from pointer
without a cast [-Wint-conversion]
10 | return strchr (s, "y"); // warning (good)
| ^~~
| |
| char *
x.c:1:7: note: expected ‘int’ but argument is of type ‘char *’
1 | char* strchr ();
| ^~~~~~
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c/95445] diagnose incompatible calls to functions declared without prototype
2020-05-30 22:32 [Bug c/95445] New: diagnose incompatible calls to functions declared without prototype msebor at gcc dot gnu.org
@ 2020-05-30 22:32 ` msebor at gcc dot gnu.org
2021-10-27 5:21 ` egallager at gcc dot gnu.org
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: msebor at gcc dot gnu.org @ 2020-05-30 22:32 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95445
Martin Sebor <msebor at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Blocks| |87403
Severity|normal |enhancement
See Also| |https://gcc.gnu.org/bugzill
| |a/show_bug.cgi?id=92212
Keywords| |diagnostic
Referenced Bugs:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87403
[Bug 87403] [Meta-bug] Issues that suggest a new warning
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c/95445] diagnose incompatible calls to functions declared without prototype
2020-05-30 22:32 [Bug c/95445] New: diagnose incompatible calls to functions declared without prototype msebor at gcc dot gnu.org
2020-05-30 22:32 ` [Bug c/95445] " msebor at gcc dot gnu.org
@ 2021-10-27 5:21 ` egallager at gcc dot gnu.org
2023-05-12 15:54 ` fw at gcc dot gnu.org
2023-05-12 16:29 ` sjames at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: egallager at gcc dot gnu.org @ 2021-10-27 5:21 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95445
Eric Gallager <egallager at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |egallager at gcc dot gnu.org
--- Comment #1 from Eric Gallager <egallager at gcc dot gnu.org> ---
Is this like clang's -Wknr-promoted-parameter?
https://clang.llvm.org/docs/DiagnosticsReference.html#wknr-promoted-parameter
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c/95445] diagnose incompatible calls to functions declared without prototype
2020-05-30 22:32 [Bug c/95445] New: diagnose incompatible calls to functions declared without prototype msebor at gcc dot gnu.org
2020-05-30 22:32 ` [Bug c/95445] " msebor at gcc dot gnu.org
2021-10-27 5:21 ` egallager at gcc dot gnu.org
@ 2023-05-12 15:54 ` fw at gcc dot gnu.org
2023-05-12 16:29 ` sjames at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: fw at gcc dot gnu.org @ 2023-05-12 15:54 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95445
Florian Weimer <fw at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |fw at gcc dot gnu.org
--- Comment #2 from Florian Weimer <fw at gcc dot gnu.org> ---
Current Clang warns like this:
t.c:17:5: warning: passing arguments to 'g' without a prototype is deprecated
in all versions of C and is not supported in C2x [-Wdeprecated-non-prototype]
g (1); // (presumably) okay, f's type is 'void (int)'
^
t.c:18:5: warning: passing arguments to 'g' without a prototype is deprecated
in all versions of C and is not supported in C2x [-Wdeprecated-non-prototype]
g ("foo"); // should be diagnosed
^
t.c:19:5: warning: passing arguments to 'g' without a prototype is deprecated
in all versions of C and is not supported in C2x [-Wdeprecated-non-prototype]
g (1, "bar"); // ditto
^
Maybe that's sufficient?
Trying to infer the type of g from its uses seems to be rather questionable.
For K&R projects, GCC already has -flto -Wlto-type-mismatch, which can diagnose
violations across translation units.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c/95445] diagnose incompatible calls to functions declared without prototype
2020-05-30 22:32 [Bug c/95445] New: diagnose incompatible calls to functions declared without prototype msebor at gcc dot gnu.org
` (2 preceding siblings ...)
2023-05-12 15:54 ` fw at gcc dot gnu.org
@ 2023-05-12 16:29 ` sjames at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: sjames at gcc dot gnu.org @ 2023-05-12 16:29 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95445
Sam James <sjames at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
See Also| |https://gcc.gnu.org/bugzill
| |a/show_bug.cgi?id=108694
--- Comment #3 from Sam James <sjames at gcc dot gnu.org> ---
I don't think we need to go beyond that (I don't really care about the uses).
That'll make this a dupe of/depends on PR108694?
^ permalink raw reply [flat|nested] 5+ messages in thread
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2020-05-30 22:32 [Bug c/95445] New: diagnose incompatible calls to functions declared without prototype msebor at gcc dot gnu.org
2020-05-30 22:32 ` [Bug c/95445] " msebor at gcc dot gnu.org
2021-10-27 5:21 ` egallager at gcc dot gnu.org
2023-05-12 15:54 ` fw at gcc dot gnu.org
2023-05-12 16:29 ` sjames at gcc dot gnu.org
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