[PATCH] Fix to 4296 - Add parser detection/error recovery for nested functions

[Serge Pavlov]

sepavloff added you to the CC list for the revision "Fix to 4296 - Add parser detection/error recovery for nested functions".

Hi doug.gregor,

Hi Doug,

This fix adds a better diagnostics for nested functions (bug 4296 - Add parser detection/error recovery for nested functions, http://llvm.org/bugs/show_bug.cgi?id=4296 ).
With this patch clang reports "function definition is not allowed here" error instead of "expected ';' at end of declaration".

Could you please review the fix?
Thank you.

--Serge

http://llvm-reviews.chandlerc.com/D542

Files:
  lib/Parse/ParseDecl.cpp
  test/Parser/nested-function.c
  include/clang/Basic/DiagnosticParseKinds.td

Index: lib/Parse/ParseDecl.cpp
===================================================================
--- lib/Parse/ParseDecl.cpp
+++ lib/Parse/ParseDecl.cpp
@@ -1489,35 +1489,42 @@
     MaybeParseGNUAttributes(D, &LateParsedAttrs);
 
   // Check to see if we have a function *definition* which must have a body.
-  if (AllowFunctionDefinitions && D.isFunctionDeclarator() &&
+  if (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);
+    if (AllowFunctionDefinitions) {
+      if (isStartOfFunctionDefinition(D)) {
+        if (DS.getStorageClassSpec() == DeclSpec::SCS_typedef) {
+          Diag(Tok, diag::err_function_declared_typedef);
 
-        // Recover by treating the 'typedef' as spurious.
-        DS.ClearStorageClassSpecs();
-      }
+          // Recover by treating the 'typedef' as spurious.
+          DS.ClearStorageClassSpecs();
+        }
 
-      Decl *TheDecl =
-        ParseFunctionDefinition(D, ParsedTemplateInfo(), &LateParsedAttrs);
-      return Actions.ConvertDeclToDeclGroup(TheDecl);
-    }
+        Decl *TheDecl =
+          ParseFunctionDefinition(D, ParsedTemplateInfo(), &LateParsedAttrs);
+        return Actions.ConvertDeclToDeclGroup(TheDecl);
+      }
 
-    if (isDeclarationSpecifier()) {
-      // If there is an invalid declaration specifier right after the function
-      // prototype, then we must be in a missing semicolon case where this isn't
-      // actually a body.  Just fall through into the code that handles it as a
-      // prototype, and let the top-level code handle the erroneous declspec
-      // where it would otherwise expect a comma or semicolon.
+      if (isDeclarationSpecifier()) {
+        // If there is an invalid declaration specifier right after the function
+        // prototype, then we must be in a missing semicolon case where this isn't
+        // actually a body.  Just fall through into the code that handles it as a
+        // prototype, and let the top-level code handle the erroneous declspec
+        // where it would otherwise expect a comma or semicolon.
+      } else {
+        Diag(Tok, diag::err_expected_fn_body);
+        SkipUntil(tok::semi);
+        return DeclGroupPtrTy();
+      }
     } else {
-      Diag(Tok, diag::err_expected_fn_body);
-      SkipUntil(tok::semi);
-      return DeclGroupPtrTy();
+      if (Tok.is(tok::l_brace)) {
+        Diag(Tok, diag::err_function_definition_not_allowed);
+        SkipUntil(tok::r_brace, true, true);
+      }
     }
   }
 
Index: test/Parser/nested-function.c
===================================================================
--- /dev/null
+++ test/Parser/nested-function.c
@@ -0,0 +1,15 @@
+// RUN: %clang_cc1 -fsyntax-only -verify %s
+
+int  func_e(int x)
+{
+    int  func_n(int y) 
+    { // expected-error {{function definition is not allowed here}}
+        if (y > 22) {
+            return y+2;
+        } else {
+            return y-2;
+        }
+    }
+
+    return x + 3;
+}
Index: include/clang/Basic/DiagnosticParseKinds.td
===================================================================
--- include/clang/Basic/DiagnosticParseKinds.td
+++ include/clang/Basic/DiagnosticParseKinds.td
@@ -352,6 +352,8 @@
   InGroup<CXX98Compat>, DefaultIgnore;
 def err_paren_after_colon_colon : Error<
   "unexpected parenthesis after '::'">;
+def err_function_definition_not_allowed : Error<
+  "function definition is not allowed here">;
 
 /// Objective-C parser diagnostics
 def err_expected_minus_or_plus : Error<
-------------- next part --------------
A non-text attachment was scrubbed...
Name: D542.1.patch
Type: text/x-patch
Size: 3880 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/cfe-commits/attachments/20130314/f76a64d2/attachment.bin>