================ @@ -0,0 +1,187 @@ +/** + * When building shared libraries, hidden objects which are defined in header + * files will be duplicated, with one copy in each shared library. If the object + * was meant to be globally unique (one copy per program), this can cause very + * subtle bugs. This file contains tests for the -Wunique-object-duplication + * warning, which is meant to detect this. + * + * Roughly, an object might be incorrectly duplicated if: + * - Is defined in a header (so it might appear in multiple TUs), and + * - Has external linkage (otherwise it's supposed to be duplicated), and + * - Has hidden visibility (or else the dynamic linker will handle it) + * + * Duplication becomes an issue only if one of the following is true: + * - The object is mutable (the copies won't be in sync), or + * - Its initialization may has side effects (it may now run more than once), or + * - The value of its address is used. + * + * Currently, we only detect the first two, and only warn on effectful + * initialization if we're certain there are side effects. Warning if the + * address is taken is prone to false positives, so we don't warn for now. + * + * The check is also disabled on Windows for now, since it uses + * dllimport/dllexport instead of visibility. + */ ---------------- DKLoehr wrote:
Fair enough; I always want more explanation when I'm looking at things, but now that it's explicitly documented we can just point to that. https://github.com/llvm/llvm-project/pull/117622 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
