[PATCH] D108403: Fix assertion when generating diagnostic for inline namespaces

[Aaron Ballman via Phabricator via cfe-commits]

aaron.ballman created this revision.
aaron.ballman added reviewers: erichkeane, rsmith, rjmccall, jyknight.
aaron.ballman requested review of this revision.
Herald added a project: clang.

When calculating the name to display for inline namespaces, we have custom logic to try to hide redundant inline namespaces from the diagnostic. Calculating these redundancies requires performing a lookup in the parent declaration context, but that lookup should not try to look through transparent declaration contexts, like linkage specifications. Instead, loop up the declaration context chain until we find a non-transparent context and use that instead.

This fixes PR49954.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D108403

Files:
  clang/include/clang/AST/Decl.h
  clang/test/Misc/diag-inline-namespace.cpp


Index: clang/test/Misc/diag-inline-namespace.cpp
===================================================================
--- clang/test/Misc/diag-inline-namespace.cpp
+++ clang/test/Misc/diag-inline-namespace.cpp
@@ -48,3 +48,14 @@
   T<struct A::B::C::i> t4; // expected-error {{implicit instantiation of undefined template 'N::T<N::A::i>'}}
   T<struct A::B::C::j> t5; // expected-error {{implicit instantiation of undefined template 'N::T<N::B::C::j>'}}
 }
+
+namespace dont_crash {
+// A malformed lookup involving inline namespaces in a linkage specification
+// would previous cause an assertion due to the way diagnostics are emitted.
+extern "C++" inline namespace {
+namespace a {
+  a : b // expected-error {{unexpected ':' in nested name specifier; did you mean '::'?}} \
+        // expected-error {{no type named 'b' in namespace 'dont_crash::a'}}
+} // expected-error {{expected unqualified-id}}
+} // inline namespace
+} // dont_crash
Index: clang/include/clang/AST/Decl.h
===================================================================
--- clang/include/clang/AST/Decl.h
+++ clang/include/clang/AST/Decl.h
@@ -614,7 +614,12 @@
     if (!isInline())
       return false;
     auto X = lookup(Name);
-    auto Y = getParent()->lookup(Name);
+    // We should not perform a lookup within a transparent context, so walk
+    // up the context chain until we find a non-transparent context.
+    const DeclContext *Parent = getParent();
+    while (Parent->isTransparentContext())
+      Parent = Parent->getParent();
+    auto Y = Parent->lookup(Name);
     return std::distance(X.begin(), X.end()) ==
       std::distance(Y.begin(), Y.end());
   }


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D108403.367593.patch
Type: text/x-patch
Size: 1661 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/cfe-commits/attachments/20210819/16809fc2/attachment-0001.bin>