Change Expr::isLvalue() to properly deal with ImplicitCastExpr's.

This fixes the following bug...

t.c:1:31: error: expression is not assignable
short x; void foo(char c) { x += c; }

This case, among others are now captured in implicit-casts.c.

llvm-svn: 41402

clang/AST/Expr.cpp

@@ -302,6 +302,8 @@ Expr::isLvalueResult Expr::isLvalue() const {
     if (cast<OCUVectorElementExpr>(this)->containsDuplicateElements())
       return LV_DuplicateVectorComponents;
     return LV_Valid;
+  case ImplicitCastExprClass: // A side-effect of our implementation.
+    return cast<ImplicitCastExpr>(this)->getSubExpr()->isLvalue();
   default:
     break;
   }

clang/test/Parser/implicit-casts.c

@@ -0,0 +1,20 @@
+// RUN: clang -parse-ast-check %s
+_Complex double X;
+void test1(int c) {
+  X = 5;
+}
+void test2() {
+  int i;
+  double d = i;
+  double _Complex a = 5;
+
+  test1(a);
+  a = 5;
+  d = i;
+}
+int test3() {
+  int a[2];
+  a[0] = test3; // expected-warning{{incompatible types assigning 'int (void)' to 'int'}}
+}
+short x; void test4(char c) { x += c; }
+int y; void test5(char c) { y += c; }