PR10101: Recover better from a common copy-paste error: if a function

declaration at namespace scope is followed by a semicolon and an open-brace
(or in C++, a 'try', ':' or '='), then the error is probably a function
definition with a spurious ';', rather than a mysterious '{'.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@145372 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 32 insertions, 11 deletions

diff --git a/lib/Parse/ParseDecl.cpp b/lib/Parse/ParseDecl.cpp
index 3bddd3de13..75c423340c 100644
--- a/lib/Parse/ParseDecl.cpp
+++ b/lib/Parse/ParseDecl.cpp
@@ -1041,13 +1041,28 @@ Parser::DeclGroupPtrTy Parser::ParseDeclGroup(ParsingDeclSpec &DS,
     return DeclGroupPtrTy();
   }
 
+  // Do we have a stray semicolon in the middle of a function definition?
+  if (AllowFunctionDefinitions && D.isFunctionDeclarator() &&
+      Tok.is(tok::semi) && Context == Declarator::FileContext) {
+    const Token &Next = NextToken();
+    if (Next.is(tok::l_brace) || Next.is(tok::kw_try) ||
+        (getLang().CPlusPlus &&
+         (Next.is(tok::colon) || Next.is(tok::equal)))) {
+      // Pretend we didn't see the semicolon.
+      SourceLocation SemiLoc = ConsumeToken();
+      Diag(SemiLoc, diag::err_stray_semi_function_definition)
+        << FixItHint::CreateRemoval(SemiLoc);
+      assert(isStartOfFunctionDefinition(D) && "expected a function defn");
+    }
+  }
+
   // Check to see if we have a function *definition* which must have a body.
   if (AllowFunctionDefinitions && D.isFunctionDeclarator() &&
       // Look at the next token to make sure that this isn't a function
       // declaration.  We have to check this because __attribute__ might be the
       // start of a function definition in GCC-extended K&R C.
       !isDeclarationAfterDeclarator()) {
-    
+
     if (isStartOfFunctionDefinition(D)) {
       if (DS.getStorageClassSpec() == DeclSpec::SCS_typedef) {
         Diag(Tok, diag::err_function_declared_typedef);
diff --git a/lib/Parse/ParseTemplate.cpp b/lib/Parse/ParseTemplate.cpp
index b485f1e977..91cf8e81c2 100644
--- a/lib/Parse/ParseTemplate.cpp
+++ b/lib/Parse/ParseTemplate.cpp
@@ -240,6 +240,20 @@ Parser::ParseSingleDeclarationAfterTemplate(
     return 0;
   }
 
+  // Check for a stray semicolon in a function definition.
+  if (DeclaratorInfo.isFunctionDeclarator() && Tok.is(tok::semi) &&
+      Context == Declarator::FileContext) {
+    const Token &Next = NextToken();
+    if (Next.is(tok::l_brace) || Next.is(tok::kw_try) ||
+        Next.is(tok::equal) || Next.is(tok::colon)) {
+      SourceLocation SemiLoc = ConsumeToken();
+      Diag(SemiLoc, diag::err_stray_semi_function_definition)
+        << FixItHint::CreateRemoval(SemiLoc);
+      assert(!isDeclarationAfterDeclarator() &&
+             isStartOfFunctionDefinition(DeclaratorInfo));
+    }
+  }
+
   // If we have a declaration or declarator list, handle it.
   if (isDeclarationAfterDeclarator()) {
     // Parse this declaration.
@@ -264,16 +278,8 @@ Parser::ParseSingleDeclarationAfterTemplate(
     if (DS.getStorageClassSpec() == DeclSpec::SCS_typedef) {
       Diag(Tok, diag::err_function_declared_typedef);
 
-      if (Tok.is(tok::l_brace)) {
-        // This recovery skips the entire function body. It would be nice
-        // to simply call ParseFunctionDefinition() below, however Sema
-        // assumes the declarator represents a function, not a typedef.
-        ConsumeBrace();
-        SkipUntil(tok::r_brace, true);
-      } else {
-        SkipUntil(tok::semi);
-      }
-      return 0;
+      // Recover by ignoring the 'typedef'.
+      DS.ClearStorageClassSpecs();
     }
     return ParseFunctionDefinition(DeclaratorInfo, TemplateInfo);
   }