[clang] Fixed issue #128882: don't warn if 1st argument to 'getcwd' is NULL (PR #135720)

[Balazs Benics via cfe-commits]

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@@ -105,9 +105,6 @@ void errno_getcwd(char *Buf, size_t Sz) {
     clang_analyzer_eval(errno != 0);   // expected-warning{{TRUE}}
     clang_analyzer_eval(Path == NULL); // expected-warning{{TRUE}}
     if (errno) {}                      // no warning
-  } else if (Path == NULL) {
-    clang_analyzer_eval(errno != 0);   // expected-warning{{TRUE}}
-    if (errno) {}                      // no warning
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steakhal wrote:

Alright. I think I understand this now.

Because of `ReturnValueCondition(BO_EQ, ArgNo(0))` on the success path we assume that the returned pointer is the same (aka. equal to) the first argument, which means that `Path` holds the same pointer as `Buf`.
Because of this, dropping the `ArgConstraint(NotNull(ArgNo(0)))` means that no longer affects the return value `Path`. This is actually a good thing.

Could you please help me how does the test failure look like for you if you would keep this hunk?

https://github.com/llvm/llvm-project/pull/135720