[PATCH] Improve error recovery around colon.

[Richard Smith]

--- lib/Parse/ParseDecl.cpp
+++ lib/Parse/ParseDecl.cpp
@@ -2706,7 +2706,7 @@
     case tok::identifier: {
       // In C++, check to see if this is a scope specifier like
foo::bar::, if
       // so handle it as such.  This is important for ctor parsing.
-      if (getLangOpts().CPlusPlus) {
+      if (getLangOpts().CPlusPlus && !DS.hasTypeSpecifier()) {

Please instead swap over this 'if' and the next one.


@@ -4508,8 +4508,10 @@
   // Member pointers get special handling, since there's no place for the
   // scope spec in the generic path below.
   if (getLangOpts().CPlusPlus &&
-      (Tok.is(tok::coloncolon) || Tok.is(tok::identifier) ||
-       Tok.is(tok::annot_cxxscope))) {
+      (Tok.is(tok::coloncolon) ||
+      (Tok.is(tok::identifier) && (NextToken().is(tok::coloncolon) ||
+                                   NextToken().is(tok::less))) ||
+      Tok.is(tok::annot_cxxscope))) {

I don't think this is quite sufficient. If we have:

  struct A { enum E {}; };
  struct B {
    static const int N = 3;
    A::E : N;
  };

... I think we might treat the : as a :: typo. Instead, drop a
ColonProtectionRAII object into this 'if', with a comment saying you're
doing it for bitfields, if you're in a member context.

On Fri, May 9, 2014 at 4:17 AM, Serge Pavlov <sepavloff at gmail.com> wrote:

> Hi Richard,
>
> Could you please review this fix?
> Thank you.
>
> --Serge
>
> Recognize additional cases, when '::' is mistyped as ':' and provide
> descriptive diagnostics for them.
> This is a fix to RP18587 - colons have too much protection in
> member-declarations
>
> http://reviews.llvm.org/D3653
>
> Files:
>   lib/Parse/ParseDecl.cpp
>   lib/Parse/ParseDeclCXX.cpp
>   test/SemaCXX/nested-name-spec.cpp
>
>
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