llvm/llvm-project
[clang] warn on operator in macro expansion whose operand doesn't lie entirely within the same macro expansion
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#184,672 opened on 2026/03/04
clang:diagnosticsgood first issue
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説明
Testcase:
#define FOO 2+3
// 2+(3*4) == 14, not (2+3)*4 == 20
int n = FOO*4;
Clang doesn't warn on this, but I think it should. In general, I think a good heuristic would be: if the location of an operator is within a macro expansion, and an operand of that operator is not entirely within that same macro expansion, then warn. In this case, the + operator within FOO has an operand that extends to the 4 token, so we should warn.
This seems like something we could quickly and easily check for with our existing source location representation.