Add a "vexing parse" warning for ambiguity between a variable declaration and a

function-style cast.

This fires for cases such as

  T(x);

... where 'x' was previously declared and T is a type. This construct declares
a variable named 'x' rather than the (probably expected) interpretation of a
function-style cast of 'x' to T.

llvm-svn: 314570

1 files changed, 24 insertions, 0 deletions

diff --git a/clang/test/SemaCXX/decl-expr-ambiguity.cpp b/clang/test/SemaCXX/decl-expr-ambiguity.cpp
index 1b1f7dc8a70..1e31d701d0c 100644
--- a/clang/test/SemaCXX/decl-expr-ambiguity.cpp
+++ b/clang/test/SemaCXX/decl-expr-ambiguity.cpp
@@ -48,13 +48,20 @@ void f() {
 
 struct RAII {
   RAII();
+  RAII(int);
   ~RAII();
 };
 
+struct NotRAII {
+  NotRAII();
+  NotRAII(int);
+};
+
 void func();
 void func2(short);
 namespace N {
   struct S;
+  int n;
 
   void emptyParens() {
     RAII raii(); // expected-warning {{function declaration}} expected-note {{remove parentheses to declare a variable}}
@@ -69,6 +76,23 @@ namespace N {
   void nonEmptyParens() {
     int f = 0, // g = 0; expected-note {{change this ',' to a ';' to call 'func2'}}
     func2(short(f)); // expected-warning {{function declaration}} expected-note {{add a pair of parentheses}}
+
+    RAII(n); // expected-warning {{parentheses were disambiguated as redundant parentheses around declaration of variable named 'n'}}
+    // expected-note@-1 {{add a variable name to declare a 'RAII' initialized with 'n'}}
+    // expected-note@-2 {{add enclosing parentheses to perform a function-style cast}}
+    // expected-note@-3 {{remove parentheses to silence this warning}}
+
+    RAII(undeclared1);
+#pragma clang diagnostic push
+#pragma clang diagnostic warning "-Wredundant-parens"
+    RAII(undeclared2); // expected-warning {{redundant parentheses surrounding declarator}}
+#pragma clang diagnostic pop
+
+    {
+      NotRAII(n); // expected-warning {{parentheses were disambiguated as redundant parentheses around declaration of variable named 'n'}}
+      // expected-note@-1 {{add enclosing parentheses to perform a function-style cast}}
+      // expected-note@-2 {{remove parentheses to silence this warning}}
+    }
   }
 }