[Frontend] The macro that describes the Objective-C bool type should be defined in C as well

[arphaman]

Summary

This patch defines __OBJC_BOOL_IS_BOOL for C code as well, since Objective-C's BOOL can be also used by C code.

[doug.gregor]

The "!LangOpts.CPlusPlus" doesn't make sense to me. You're presumably defining this macro in C because the Objective-C runtime is usable from C, but that same logic applies to C++ code. It seems like we should be defining this macro unconditionally.

[arphaman]

Set the macro unconditionally.

[arphaman]

In D28349#636968, @doug.gregor wrote:

The "!LangOpts.CPlusPlus" doesn't make sense to me. You're presumably defining this macro in C because the Objective-C runtime is usable from C, but that same logic applies to C++ code. It seems like we should be defining this macro unconditionally.

That's true. I was initially reluctant to define it for C++ as well since this macro is available on all platforms, but I guess there's no way around this.

[arphaman]

Ping.

[mehdi_amini]

LGTM.

lib/Frontend/InitPreprocessor.cpp

#undef TOSTR2
   if (LangOpts.ObjC1) {
     if (LangOpts.ObjCRuntime.isNonFragile()) {
       Builder.defineMacro("__OBJC2__");
       
       if (LangOpts.ObjCExceptions)
         Builder.defineMacro("OBJC_ZEROCOST_EXCEPTIONS");
     }
 
-    Builder.defineMacro("__OBJC_BOOL_IS_BOOL",
-                        Twine(TI.useSignedCharForObjCBool() ? "0" : "1"));
-
     if (LangOpts.getGC() != LangOptions::NonGC)
       Builder.defineMacro("__OBJC_GC__");
 
     if (LangOpts.ObjCRuntime.isNeXTFamily())
       Builder.defineMacro("__NEXT_RUNTIME__");
 
     if (LangOpts.ObjCRuntime.getKind() == ObjCRuntime::ObjFW) {
       VersionTuple tuple = LangOpts.ObjCRuntime.getVersion();
if (LangOpts.ObjC1) {
     Builder.defineMacro("IBOutlet", "__attribute__((iboutlet))");
     Builder.defineMacro("IBOutletCollection(ClassName)",
                         "__attribute__((iboutletcollection(ClassName)))");
     Builder.defineMacro("IBAction", "void)__attribute__((ibaction)");
     Builder.defineMacro("IBInspectable", "");
     Builder.defineMacro("IB_DESIGNABLE", "");
   }
 
+  // Define a macro that describes the Objective-C boolean type for both
+  // Objective-C/C++ and plain C code.
+  if (LangOpts.ObjC1 || !LangOpts.CPlusPlus)
+    Builder.defineMacro("__OBJC_BOOL_IS_BOOL",
+                        Twine(TI.useSignedCharForObjCBool() ? "0" : "1"));
+
   if (LangOpts.CPlusPlus)
     InitializeCPlusPlusFeatureTestMacros(LangOpts, Builder);
 
   // darwin_constant_cfstrings controls this. This is also dependent
   // on other things like the runtime I believe.  This is set even for C code.
   if (!LangOpts.NoConstantCFStrings)
       Builder.defineMacro("__CONSTANT_CFSTRINGS__");
 

test/Frontend/objc-bool-is-bool.m

 // RUN: %clang_cc1 -fsyntax-only -E -dM -triple=armv7k-apple-watchos %s | FileCheck --check-prefix=BOOL %s
 // RUN: %clang_cc1 -fsyntax-only -E -dM -triple=x86_64-apple-darwin16 %s | FileCheck --check-prefix=CHAR %s
-// RUN: %clang_cc1 -x c -fsyntax-only -E -dM -triple=x86_64-apple-darwin16 %s | FileCheck --check-prefix=NONE %s
+// RUN: %clang_cc1 -x c -fsyntax-only -E -dM -triple=x86_64-apple-darwin16 %s | FileCheck --check-prefix=CHAR %s
+// RUN: %clang_cc1 -x objective-c++ -fsyntax-only -E -dM -triple=x86_64-apple-darwin16 %s | FileCheck --check-prefix=CHAR %s
+// RUN: %clang_cc1 -x c++ -fsyntax-only -E -dM -triple=x86_64-apple-darwin16 %s | FileCheck --check-prefix=NONE %s
 
 // rdar://21170440
 
 // BOOL: #define __OBJC_BOOL_IS_BOOL 1
 // BOOL-NOT: #define __OBJC_BOOL_IS_BOOL 0
 
 // CHAR: #define __OBJC_BOOL_IS_BOOL 0
 // CHAR-NOT: #define __OBJC_BOOL_IS_BOOL 1
 
 // NONE-NOT: __OBJC_BOOL_IS_BOOL