Warnings about nonsensical comparisons are disabled if macro expansion is involved

[llunak]

Bugzilla Link	12463
Version	trunk
OS	Linux
Attachments	clang patch, clang patch

Extended Description

$ cat a.cpp

#define FOO "foo"
#define BAR "bar"
bool foo()
    {
    bool b;
    b = FOO == BAR;
    b = "foo" == "bar";
    return b;
    }

$ clang++ -Wall a.cpp -c
a.cpp:7:15: warning: result of comparison against a string literal is unspecified (use strncmp instead) [-Wstring-compare]
    b = "foo" == "bar";
        ~~~~~ ^
1 warning generated.                                                                                                         

Line 6 should generate a warning as well. As the warning says, the result of such a comparison is unspecified, so it is never correct, even if it comes from a macro expansion.

[YutongZhuu]

I believe this issue is fixed: https://godbolt.org/z/Kr1E8qfjo. We can close this issue. @Endilll

[Endilll]

Appears to be fixed in Clang 20.1: https://godbolt.org/z/bvz3e3sbq