[PATCH] D23684: Resolve ambiguity in a declaration if global nested name specifier is used

[Serge Pavlov via cfe-commits]

sepavloff created this revision.
sepavloff added reviewers: rsmith, doug.gregor.
sepavloff added a subscriber: cfe-commits.

If a declaration references a function from global namespace by its
qualified name and if that function return type is a class or enum, there
is possible ambiguity. The declaration:
```
    friend A::B::C();
```
may be considered as a declaration of a function `::C()` that returns
`A::B`, or a function `::B::C()` that returns `A`.

With this change when the compiler sees 'A::B' while parsing decl-spec, it
tries to find `B` within 'A'. If it finds, 'A::B' is treated as a part of
qualified name. If it doesn't and the current declaration declares a
function, '::B' is assumed to be a part of declarator. For non-function
declarations 'B' can be searched for in the global namespace to improve
diagnostics.

This changes fixes https://llvm.org/bugs/show_bug.cgi?id=28422.

https://reviews.llvm.org/D23684

Files:
  include/clang/Parse/Parser.h
  include/clang/Sema/Sema.h
  lib/Parse/ParseDecl.cpp
  lib/Parse/ParseDeclCXX.cpp
  lib/Parse/ParseExprCXX.cpp
  lib/Parse/Parser.cpp
  lib/Parse/RAIIObjectsForParser.h
  lib/Sema/SemaCXXScopeSpec.cpp
  lib/Sema/TreeTransform.h
  test/CXX/drs/dr1xx.cpp
  test/CXX/drs/dr2xx.cpp
  test/Parser/cxx-decl.cpp
  test/SemaCXX/nested-name-spec2.cpp
  test/SemaCXX/pr18284-crash-on-invalid.cpp
  test/SemaCXX/typo-correction.cpp

-------------- next part --------------
A non-text attachment was scrubbed...
Name: D23684.68583.patch
Type: text/x-patch
Size: 33609 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/cfe-commits/attachments/20160818/f2e8460a/attachment-0001.bin>