Fix duplicate messages for illegal void pointer arithmetic. #563
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The compiler was emitting duplicate error messages for void pointer arithmetic involving checking pointers in bounds expressions. The problem was that the logic for marking the expression is invalid is separate from actually emitting the diagnostic. The logic only looked for the language being C++. The fix is to look for the conditions related to Checked C also. This caused a duplicate error messages beccause the expression wasn't turned into an invalid expression. When a subsequent TreeTransform pass for bounds declaration checking ran, it emitted the diagnostic a second time when it encountered the expression again. I noticed that we had some logic for handling pointer arithmetic involving function pointers. This is allowed by a GCC extension. For checked pointers, we never allow _Array_ptrs to function pointers. We only allow _Ptrs to function pointers. Pointer arithmetic is never allowed for _Ptrs, so we never reach this logic. I converted the logic to an assert and added some comments. Testing: - I added a new Checked C clang regression test for these cases that checks that only one error message is emitted.
I wrote some additional tests. It turns out the code paths where I added assert are reached even for checked pointers. Remove asserts and add test casss that make sure that other errors that should logically preclude the pointer arithmetic actually occur.
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The compiler was emitting duplicate error messages for void pointer arithmetic using checked pointers in bounds expressions. The problem was that the logic for marking the expression as invalid is separate from actually emitting the diagnostic. The logic only looked for the language being C++. The fix is to look for the conditions related to Checked C also. This fixes issue #543.
This caused a duplicate error messages because the expression wasn't turned into an invalid expression. When a subsequent TreeTransform pass for bounds declaration checking ran, it emitted the diagnostic a second time when it encountered the expression again.
I noticed that we had some logic for handling pointer arithmetic involving function pointers. This is allowed by a GCC extension. For checked pointers, we never allow _Array_ptrs to function pointers. We only allow _Ptrs to function pointers. Pointer arithmetic is never allowed for _Ptrs, so we never reach this logic. I converted the logic to an assert and added some comments.
Testing: