When a type-id is unexpectedly given a name, assume that the name is unrelated

syntax unless we have a reason to think otherwise.

This improves error recovery in a couple of cases.

llvm-svn: 303398

1 files changed, 22 insertions, 5 deletions

diff --git a/clang/lib/Parse/ParseDecl.cpp b/clang/lib/Parse/ParseDecl.cpp
index 69e1af0ed0b..b785f5f7d2e 100644
--- a/clang/lib/Parse/ParseDecl.cpp
+++ b/clang/lib/Parse/ParseDecl.cpp
@@ -5542,11 +5542,28 @@ void Parser::ParseDirectDeclarator(Declarator &D) {
     D.SetRangeEnd(Tok.getLocation());
     ConsumeToken();
     goto PastIdentifier;
-  } else if (Tok.is(tok::identifier) && D.diagnoseIdentifier()) {
-    // A virt-specifier isn't treated as an identifier if it appears after a
-    // trailing-return-type.
-    if (D.getContext() != Declarator::TrailingReturnContext ||
-        !isCXX11VirtSpecifier(Tok)) {
+  } else if (Tok.is(tok::identifier) && !D.mayHaveIdentifier()) {
+    // We're not allowed an identifier here, but we got one. Try to figure out
+    // if the user was trying to attach a name to the type, or whether the name
+    // is some unrelated trailing syntax.
+    bool DiagnoseIdentifier = false;
+    if (D.hasGroupingParens())
+      // An identifier within parens is unlikely to be intended to be anything
+      // other than a name being "declared".
+      DiagnoseIdentifier = true;
+    else if (D.getContext() == Declarator::TemplateTypeArgContext)
+      // T<int N> is an accidental identifier; T<int N indicates a missing '>'.
+      DiagnoseIdentifier =
+          NextToken().isOneOf(tok::comma, tok::greater, tok::greatergreater);
+    else if (D.getContext() == Declarator::AliasDeclContext ||
+             D.getContext() == Declarator::AliasTemplateContext)
+      // The most likely error is that the ';' was forgotten.
+      DiagnoseIdentifier = NextToken().isOneOf(tok::comma, tok::semi);
+    else if (D.getContext() == Declarator::TrailingReturnContext &&
+             !isCXX11VirtSpecifier(Tok))
+      DiagnoseIdentifier = NextToken().isOneOf(
+          tok::comma, tok::semi, tok::equal, tok::l_brace, tok::kw_try);
+    if (DiagnoseIdentifier) {
       Diag(Tok.getLocation(), diag::err_unexpected_unqualified_id)
         << FixItHint::CreateRemoval(Tok.getLocation());
       D.SetIdentifier(nullptr, Tok.getLocation());