llvm-project

e16882fc - fix bug that undefined internal is a warning only for -pedantic-errors (#98016)

fix bug that undefined internal is a warning only for -pedantic-errors (#98016) This fixes issue #39558 which mentions the problem when compiling the following code with `-pedantic-errors` flag (it also mentions `-Wall -Wextra` but those shouldn't change the output, which is also the case in GCC): ```c static void f(); int main() { f; } ``` Clang only outputs an `undefined-internal` warning on the first line, but according to 6.9/3 ``` "... Moreover, if an identifier declared with internal linkage is used in an expression (other than as a part of the operand of a sizeof or _Alignof operator whose result is an integer constant), there shall be exactly one external definition for the identifier in the translation unit." ``` this should be illegal and hence an error. I fixed this by changing the warning type from `Warning` to `ExtWarn` and by adding a suitable test.