fcloutier added inline comments.
================
Comment at: clang/test/SemaCXX/attr-format.cpp:76
+ format("bare string");
+ format("%s", 123); // expected-warning{{format specifies type 'char *' but
the argument has type 'int'}}
+ format("%s %s %u %d %i %p\n", "hello", s, 10u, x, y, &do_format);
----------------
aaron.ballman wrote:
> This pointed out an interesting test case. What should the behavior be for:
> ```
> format("%p", 0);
> ```
> Because that sure feels like a more reasonable thing for someone to write
> expecting it to be treated as a null pointer constant.
I think that the current behavior is the right one:
```
test.c:4:17: warning: format specifies type 'void *' but the argument has type
'int' [-Wformat]
printf("%p\n", 0);
~~ ^
%d
```
The warning goes away if you use `(void *)0`, as expected.
`__attribute__((format))` has no semantic meaning, so we can't (and shouldn't)
infer that 0 is a pointer based on the usage of %p.
================
Comment at: clang/test/SemaCXX/attr-format.cpp:77-78
+ format("%s", 123); // expected-warning{{format specifies type 'char *' but
the argument has type 'int'}}
+ format("%s %s %u %d %i %p\n", "hello", s, 10u, x, y, &do_format);
+ format("%s %s %u %d %i %p\n", "hello", s, 10u, x, y, do_format);
+ format("bad format %s"); // expected-warning{{more '%' conversions than data
arguments}}
----------------
aaron.ballman wrote:
> This likely isn't specific to your changes, but the `%p` in these examples
> should be warning the user (a function or function pointer is not a pointer
> to void or a pointer to a character type, so that call is UB).
This is already a -Wformat-pedantic warning, which IMO is the right warning
group for it:
```
test.c:4:17: warning: format specifies type 'void *' but the argument has type
'int (*)()' [-Wformat-pedantic]
printf("%p\n", main);
~~ ^~~~
1 warning generated.
```
The relevant bit is clang/lib/AST/FormatString.cpp:
```
case CPointerTy:
if (argTy->isVoidPointerType()) {
return Match;
} if (argTy->isPointerType() || argTy->isObjCObjectPointerType() ||
argTy->isBlockPointerType() || argTy->isNullPtrType()) {
return NoMatchPedantic;
} else {
return NoMatch;
}
```
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D112579/new/
https://reviews.llvm.org/D112579
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