[PATCH] Objective-C literals to bool conversion warning

[Richard Trieu]

  "implicit conversion" -> "implicit boolean conversion"

http://llvm-reviews.chandlerc.com/D2608

CHANGE SINCE LAST DIFF
  http://llvm-reviews.chandlerc.com/D2608?vs=6727&id=6729#toc

Files:
  lib/Sema/SemaChecking.cpp
  test/SemaObjCXX/warn-objc-literal-conversion.mm
  include/clang/Basic/DiagnosticGroups.td
  include/clang/Basic/DiagnosticSemaKinds.td

Index: lib/Sema/SemaChecking.cpp
===================================================================
--- lib/Sema/SemaChecking.cpp
+++ lib/Sema/SemaChecking.cpp
@@ -5350,6 +5350,13 @@
       // prevented by a check in AnalyzeImplicitConversions().
       return DiagnoseImpCast(S, E, T, CC,
                              diag::warn_impcast_string_literal_to_bool);
+    if (isa<ObjCStringLiteral>(E) || isa<ObjCArrayLiteral>(E) ||
+        isa<ObjCDictionaryLiteral>(E) || isa<ObjCBoxedExpr>(E)) {
+      // This covers the literal expressions that evaluate to Objective-C
+      // objects.
+      return DiagnoseImpCast(S, E, T, CC,
+                             diag::warn_impcast_objective_c_literal_to_bool);
+    }
     if (Source->isFunctionType()) {
       // Warn on function to bool. Checks free functions and static member
       // functions. Weakly imported functions are excluded from the check,
Index: test/SemaObjCXX/warn-objc-literal-conversion.mm
===================================================================
--- test/SemaObjCXX/warn-objc-literal-conversion.mm
+++ test/SemaObjCXX/warn-objc-literal-conversion.mm
@@ -0,0 +1,74 @@
+// RUN: %clang_cc1 -fsyntax-only -verify -Wobjc-literal-conversion %s
+
+ at class NSString;
+
+ at interface NSNumber
++ (NSNumber *)numberWithChar:(char)value;
++ (NSNumber *)numberWithInt:(int)value;
++ (NSNumber *)numberWithLongLong:(long long)value;
++ (NSNumber *)numberWithFloat:(float)value;
++ (NSNumber *)numberWithDouble:(double)value;
++ (NSNumber *)numberWithBool:(bool)value;
+ at end
+
+ at interface NSArray
++ (id)arrayWithObjects:(const id [])objects count:(int)cnt;
+ at end
+
+ at interface NSDictionary
++ (id)dictionaryWithObjects:(const id [])objects forKeys:(const id [])keys count:(unsigned long)cnt;
+ at end
+
+void char_test() {
+  if (@'a') {}
+  // expected-warning at -1{{implicit boolean conversion of Objective-C object literal always evaluates to true}}
+}
+
+void int_test() {
+  if (@12) {}
+  // expected-warning at -1{{implicit boolean conversion of Objective-C object literal always evaluates to true}}
+  if (@-12) {}
+  // expected-warning at -1{{implicit boolean conversion of Objective-C object literal always evaluates to true}}
+  if (@12LL) {}
+  // expected-warning at -1{{implicit boolean conversion of Objective-C object literal always evaluates to true}}
+  if (@-12LL) {}
+  // expected-warning at -1{{implicit boolean conversion of Objective-C object literal always evaluates to true}}
+}
+
+void float_test() {
+  if (@12.55) {}
+  // expected-warning at -1{{implicit boolean conversion of Objective-C object literal always evaluates to true}}
+  if (@-12.55) {}
+  // expected-warning at -1{{implicit boolean conversion of Objective-C object literal always evaluates to true}}
+  if (@12.55F) {}
+  // expected-warning at -1{{implicit boolean conversion of Objective-C object literal always evaluates to true}}
+  if (@-12.55F) {}
+  // expected-warning at -1{{implicit boolean conversion of Objective-C object literal always evaluates to true}}
+}
+
+void bool_test() {
+  if (@true) {}
+  // expected-warning at -1{{implicit boolean conversion of Objective-C object literal always evaluates to true}}
+  if (@false) {}
+  // expected-warning at -1{{implicit boolean conversion of Objective-C object literal always evaluates to true}}
+}
+
+void string_test() {
+  if (@"asdf") {}
+  // expected-warning at -1{{implicit boolean conversion of Objective-C object literal always evaluates to true}}
+}
+
+void array_test() {
+  if (@[ @313, @331, @367, @379 ]) {}
+  // expected-warning at -1{{implicit boolean conversion of Objective-C object literal always evaluates to true}}
+}
+
+void dictionary_test() {
+  if (@{ @0: @0, @1: @1, @2: @1, @3: @3 }) {}
+  // expected-warning at -1{{implicit boolean conversion of Objective-C object literal always evaluates to true}}
+}
+
+void objc_bool_test () {
+  if (__objc_yes) {}
+  if (__objc_no) {}
+}
Index: include/clang/Basic/DiagnosticGroups.td
===================================================================
--- include/clang/Basic/DiagnosticGroups.td
+++ include/clang/Basic/DiagnosticGroups.td
@@ -44,6 +44,7 @@
 def NullConversion : DiagGroup<"null-conversion">;
 def ImplicitConversionFloatingPointToBool :
   DiagGroup<"implicit-conversion-floating-point-to-bool">;
+def ObjCLiteralConversion : DiagGroup<"objc-literal-conversion">;
 def BadArrayNewLength : DiagGroup<"bad-array-new-length">;
 def BuiltinMacroRedefined : DiagGroup<"builtin-macro-redefined">;
 def BuiltinRequiresHeader : DiagGroup<"builtin-requires-header">;
@@ -446,6 +447,7 @@
                             LiteralConversion,
                             NonLiteralNullConversion, // (1-1)->pointer (etc)
                             NullConversion, // NULL->non-pointer
+                            ObjCLiteralConversion,
                             SignConversion,
                             StringConversion]>,
                  DiagCategory<"Value Conversion Issue">;
Index: include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- include/clang/Basic/DiagnosticSemaKinds.td
+++ include/clang/Basic/DiagnosticSemaKinds.td
@@ -2296,6 +2296,10 @@
     "prefix with the address-of operator to silence this warning">;
 def note_function_to_bool_call : Note<
     "suffix with parentheses to turn this into a function call">;
+def warn_impcast_objective_c_literal_to_bool : Warning<
+    "implicit boolean conversion of Objective-C object literal always "
+    "evaluates to true">,
+    InGroup<ObjCLiteralConversion>, DefaultIgnore;
 
 def warn_cast_align : Warning<
   "cast from %0 to %1 increases required alignment from %2 to %3">,
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