Improve diagnostic reporting when using __declspec without enabling __declspec as a keyword.

Fixes PR31936.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@295114 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 25 insertions, 0 deletions

diff --git a/lib/Parse/ParseDecl.cpp b/lib/Parse/ParseDecl.cpp
index 7ffafe2dab..e0347ccf2f 100644
--- a/lib/Parse/ParseDecl.cpp
+++ b/lib/Parse/ParseDecl.cpp
@@ -2966,6 +2966,31 @@ void Parser::ParseDeclarationSpecifiers(DeclSpec &DS,
       if (DS.hasTypeSpecifier())
         goto DoneWithDeclSpec;
 
+      // If the token is an identifier named "__declspec" and Microsoft
+      // extensions are not enabled, it is likely that there will be cascading
+      // parse errors if this really is a __declspec attribute. Attempt to
+      // recognize that scenario and recover gracefully.
+      if (!getLangOpts().DeclSpecKeyword && Tok.is(tok::identifier) &&
+          Tok.getIdentifierInfo()->getName().equals("__declspec")) {
+        Diag(Loc, diag::err_ms_attributes_not_enabled);
+
+        // The next token should be an open paren. If it is, eat the entire
+        // attribute declaration and continue.
+        if (NextToken().is(tok::l_paren)) {
+          // Consume the __declspec identifier.
+          SourceLocation Loc = ConsumeToken();
+
+          // Eat the parens and everything between them.
+          BalancedDelimiterTracker T(*this, tok::l_paren);
+          if (T.consumeOpen()) {
+            assert(false && "Not a left paren?");
+            return;
+          }
+          T.skipToEnd();
+          continue;
+        }
+      }
+
       // 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) {