Disambiguate between a declaration or an expression, in the 'for-init-statement' part of a 'for' statement.

llvm-svn: 57112

clang/include/clang/Parse/Parser.h

@@ -590,6 +590,16 @@ private:
     return isDeclarationSpecifier();
   }
 
+  /// isSimpleDeclaration - Disambiguates between a declaration or an
+  /// expression, mainly used for the C 'clause-1' or the C++
+  // 'for-init-statement' part of a 'for' statement.
+  /// Returns true for declaration, false for expression.
+  bool isSimpleDeclaration() {
+    if (getLang().CPlusPlus)
+      return isCXXSimpleDeclaration();
+    return isDeclarationSpecifier();
+  }
+
   /// isCXXDeclarationStatement - C++-specialized function that disambiguates
   /// between a declaration or an expression statement, when parsing function
   /// bodies. Returns true for declaration, false for expression.

clang/lib/Parse/ParseStmt.cpp

@@ -813,7 +813,7 @@ Parser::StmtResult Parser::ParseForStatement() {
   if (Tok.is(tok::semi)) {  // for (;
     // no first part, eat the ';'.
     ConsumeToken();
-  } else if (isDeclarationSpecifier()) {  // for (int X = 4;
+  } else if (isSimpleDeclaration()) {  // for (int X = 4;
     // Parse declaration, which eats the ';'.
     if (!C99orCXX)   // Use of C99-style for loops in C90 mode?
       Diag(Tok, diag::ext_c99_variable_decl_in_for_loop);

clang/test/SemaCXX/decl-expr-ambiguity.cpp

@@ -12,6 +12,7 @@ void f() {
   typeof(int)(a,5)<<a; // expected-error {{function-style cast to a builtin type can only take one argument}}
   void(a), ++a; // expected-warning {{statement was disambiguated as expression}} expected-warning {{expression result unused}}
   if (int(a)+1) {}
+  for (int(a)+1;;) {}
 
   // Declarations.
   T(*d)(int(p)); // expected-warning {{statement was disambiguated as declaration}} expected-error {{previous definition is here}}