diff options
author | Richard Smith <richard-llvm@metafoo.co.uk> | 2017-10-09 23:42:09 +0000 |
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committer | Richard Smith <richard-llvm@metafoo.co.uk> | 2017-10-09 23:42:09 +0000 |
commit | 9ee4a4e444f01064a5771f7d6b8839c6b175fbbe (patch) | |
tree | abb9aa11dd6bf633bc2226c26cf70b02af3291b8 /lib/Sema/SemaLookup.cpp | |
parent | a167502bf9cf5f494c8e5ebcf28be822809b013f (diff) |
[Modules TS] Module ownership semantics for redeclarations.
When declaring an entity in the "purview" of a module, it's never a
redeclaration of an entity in the purview of a default module or in no module
("in the global module"). Don't consider those other declarations as possible
redeclaration targets if they're not visible, and reject any cases where we
pick a prior visible declaration that violates this rule.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@315251 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/Sema/SemaLookup.cpp')
-rw-r--r-- | lib/Sema/SemaLookup.cpp | 30 |
1 files changed, 29 insertions, 1 deletions
diff --git a/lib/Sema/SemaLookup.cpp b/lib/Sema/SemaLookup.cpp index a89d3ace24..6fb0260075 100644 --- a/lib/Sema/SemaLookup.cpp +++ b/lib/Sema/SemaLookup.cpp @@ -1609,11 +1609,39 @@ bool Sema::isVisibleSlow(const NamedDecl *D) { } bool Sema::shouldLinkPossiblyHiddenDecl(LookupResult &R, const NamedDecl *New) { + // FIXME: If there are both visible and hidden declarations, we need to take + // into account whether redeclaration is possible. Example: + // + // Non-imported module: + // int f(T); // #1 + // Some TU: + // static int f(U); // #2, not a redeclaration of #1 + // int f(T); // #3, finds both, should link with #1 if T != U, but + // // with #2 if T == U; neither should be ambiguous. for (auto *D : R) { if (isVisible(D)) return true; + assert(D->isExternallyDeclarable() && + "should not have hidden, non-externally-declarable result here"); } - return New->isExternallyVisible(); + + // This function is called once "New" is essentially complete, but before a + // previous declaration is attached. We can't query the linkage of "New" in + // general, because attaching the previous declaration can change the + // linkage of New to match the previous declaration. + // + // However, because we've just determined that there is no *visible* prior + // declaration, we can compute the linkage here. There are two possibilities: + // + // * This is not a redeclaration; it's safe to compute the linkage now. + // + // * This is a redeclaration of a prior declaration that is externally + // redeclarable. In that case, the linkage of the declaration is not + // changed by attaching the prior declaration, because both are externally + // declarable (and thus ExternalLinkage or VisibleNoLinkage). + // + // FIXME: This is subtle and fragile. + return New->isExternallyDeclarable(); } /// \brief Retrieve the visible declaration corresponding to D, if any. |