Add a warning for implicit conversion from function literals (and static
methods) to bool. E.g.

void foo() {}
if (f) { ... // <- Warns here.
}

Only applies to non-weak functions, and does not apply if the function address
is taken explicitly with the addr-of operator.

llvm-svn: 145849
diff --git a/clang/test/CXX/over/over.over/p2-resolve-single-template-id.cpp b/clang/test/CXX/over/over.over/p2-resolve-single-template-id.cpp
index 1bd0d34..470894990 100644
--- a/clang/test/CXX/over/over.over/p2-resolve-single-template-id.cpp
+++ b/clang/test/CXX/over/over.over/p2-resolve-single-template-id.cpp
@@ -100,8 +100,8 @@
   { (void) reinterpret_cast<int>(two); } //expected-error {{reinterpret_cast}}
   { (void) reinterpret_cast<int (*)(char, double)>(two); } //expected-error {{reinterpret_cast}}
 
-  { bool b = (twoT<int>); } // ok
-  { bool b = (twoT<int, int>); } //ok
+  { bool b = (twoT<int>); } // expected-warning {{address of function 'twoT<int>' will always evaluate to 'true'}}
+  { bool b = (twoT<int, int>); } // expected-warning {{address of function 'twoT<int, int>' will always evaluate to 'true'}}
 
   { bool b = &twoT<int>; //&foo<int>; }
     b = &(twoT<int>); }
@@ -142,20 +142,20 @@
     if (&s.f<char>) return; // expected-error {{cannot create a non-constant pointer to member function}}
     if (&s.f<int>) return; // expected-error {{cannot create a non-constant pointer to member function}}
 
-    if (S::g<char>) return;
-    if (S::g<int>) return;
+    if (S::g<char>) return; // expected-warning {{address of function 'member_pointers::S::g<char>' will always evaluate to 'true'}}
+    if (S::g<int>) return; // expected-warning {{address of function 'member_pointers::S::g<int>' will always evaluate to 'true'}}
     if (&S::g<char>) return;
     if (&S::g<int>) return;
-    if (s.g<char>) return;
-    if (s.g<int>) return;
+    if (s.g<char>) return; // expected-warning {{address of function 'member_pointers::S::g<char>' will always evaluate to 'true'}}
+    if (s.g<int>) return; // expected-warning {{address of function 'member_pointers::S::g<int>' will always evaluate to 'true'}}
     if (&s.g<char>) return;
     if (&s.g<int>) return;
 
-    if (S::h<42>) return;
+    if (S::h<42>) return; // expected-warning {{address of function 'member_pointers::S::h<42>' will always evaluate to 'true'}}
     if (S::h<int>) return; // expected-error {{reference to overloaded function could not be resolved; did you mean to call it?}}
     if (&S::h<42>) return;
     if (&S::h<int>) return;
-    if (s.h<42>) return;
+    if (s.h<42>) return;  // expected-warning {{address of function 'member_pointers::S::h<42>' will always evaluate to 'true'}}
     if (s.h<int>) return; // expected-error {{reference to overloaded function could not be resolved; did you mean to call it?}}
     if (&s.h<42>) return;
     if (&s.h<int>) return; // expected-error {{reference to overloaded function could not be resolved; did you mean to call it?}}
@@ -170,20 +170,20 @@
     { bool b = &s.f<char>; } // expected-error {{cannot create a non-constant pointer to member function}}
     { bool b = &s.f<int>; } // expected-error {{cannot create a non-constant pointer to member function}}
 
-    { bool b = S::g<char>; }
-    { bool b = S::g<int>; }
+    { bool b = S::g<char>; } // expected-warning {{address of function 'member_pointers::S::g<char>' will always evaluate to 'true'}}
+    { bool b = S::g<int>; } // expected-warning {{address of function 'member_pointers::S::g<int>' will always evaluate to 'true'}}
     { bool b = &S::g<char>; }
     { bool b = &S::g<int>; }
-    { bool b = s.g<char>; }
-    { bool b = s.g<int>; }
+    { bool b = s.g<char>; }  // expected-warning {{address of function 'member_pointers::S::g<char>' will always evaluate to 'true'}}
+    { bool b = s.g<int>; } // expected-warning {{address of function 'member_pointers::S::g<int>' will always evaluate to 'true'}}
     { bool b = &s.g<char>; }
     { bool b = &s.g<int>; }
 
-    { bool b = S::h<42>; }
+    { bool b = S::h<42>; } // expected-warning {{address of function 'member_pointers::S::h<42>' will always evaluate to 'true'}}
     { bool b = S::h<int>; } // expected-error {{can't form member pointer of type 'bool' without '&' and class name}}
     { bool b = &S::h<42>; }
     { bool b = &S::h<int>; }
-    { bool b = s.h<42>; }
+    { bool b = s.h<42>; }  // expected-warning {{address of function 'member_pointers::S::h<42>' will always evaluate to 'true'}}
     { bool b = s.h<int>; } // expected-error {{can't form member pointer of type 'bool' without '&' and class name}}
     { bool b = &s.h<42>; }
     { bool b = &s.h<int>; } // expected-error {{can't form member pointer of type 'bool' without '&' and class name}}
diff --git a/clang/test/SemaCXX/condition.cpp b/clang/test/SemaCXX/condition.cpp
index 3441bae..21671fa 100644
--- a/clang/test/SemaCXX/condition.cpp
+++ b/clang/test/SemaCXX/condition.cpp
@@ -49,6 +49,6 @@
   if ("help")
     (void) 0;
 
-  if (test3)
+  if (test3) // expected-warning {{address of function 'test3' will always evaluate to 'true'}}
     (void) 0;
 }
diff --git a/clang/test/SemaTemplate/resolve-single-template-id.cpp b/clang/test/SemaTemplate/resolve-single-template-id.cpp
index b9833d8..1beb65a 100644
--- a/clang/test/SemaTemplate/resolve-single-template-id.cpp
+++ b/clang/test/SemaTemplate/resolve-single-template-id.cpp
@@ -41,7 +41,7 @@
   *oneT<int>;   // expected-warning {{expression result unused}}
   *two;  //expected-error {{reference to overloaded function could not be resolved; did you mean to call it with no arguments?}} expected-error {{indirection requires pointer operand}}
   *twoT<int>; //expected-error {{reference to overloaded function could not be resolved; did you mean to call it?}}
-  !oneT<int>;  // expected-warning {{expression result unused}}
+  !oneT<int>;  // expected-warning {{expression result unused}} expected-warning {{address of function 'oneT<int>' will always evaluate to 'true'}}
   +oneT<int>;  // expected-warning {{expression result unused}}
   -oneT<int>;  //expected-error {{invalid argument type}}
   oneT<int> == 0;   // expected-warning {{equality comparison result unused}} \
@@ -53,7 +53,7 @@
   
   int i = (int) (false ? (void (*)(int))twoT<int> : oneT<int>); //expected-error {{incompatible operand}}
   (twoT<int>) == oneT<int>; //expected-error {{reference to overloaded function could not be resolved; did you mean to call it?}} {{cannot resolve overloaded function 'twoT' from context}}
-  bool b = oneT<int>;
+  bool b = oneT<int>; // expected-warning {{address of function 'oneT<int>' will always evaluate to 'true'}}
   void (*p)() = oneT<int>;
   test<oneT<int> > ti;
   void (*u)(int) = oneT<int>;