Define __ANDROID_API__ when specified as part of an Android target.

[srhines]

Summary

This macro should be defined only when the user directly specifies an
API level as part of an Android target. For any regular Android target,
we leave this macro undefined.

Bug: https://llvm.org/bugs/show_bug.cgi?id=30940

[srhines]

Added bug link to commit message.

[pirama]

The "Bug" line points back to this Phab page instead of a bug. LGTM otherwise.

[eugenis]

Looks great!

cfe/trunk/lib/Basic/Targets.cpp

void getOSDefines(const LangOptions &Opts, const llvm::Triple &Triple,
     Builder.defineMacro("__gnu_linux__");
     Builder.defineMacro("__ELF__");
     if (Triple.isAndroid()) {
       Builder.defineMacro("__ANDROID__", "1");
       unsigned Maj, Min, Rev;
       Triple.getEnvironmentVersion(Maj, Min, Rev);
       this->PlatformName = "android";
       this->PlatformMinVersion = VersionTuple(Maj, Min, Rev);
+      if (Maj)
+        Builder.defineMacro("__ANDROID_API__", Twine(Maj));
     }
     if (Opts.POSIXThreads)
       Builder.defineMacro("_REENTRANT");
     if (Opts.CPlusPlus)
       Builder.defineMacro("_GNU_SOURCE");
     if (this->HasFloat128)
       Builder.defineMacro("__FLOAT128__");
   }

cfe/trunk/test/Preprocessor/init.c

 // GNUSOURCE:#define _GNU_SOURCE 1
 //
 // RUN: %clang_cc1 -x c++ -std=c++98 -fno-rtti -E -dM < /dev/null | FileCheck -match-full-lines -check-prefix NORTTI %s
 // NORTTI: #define __GXX_ABI_VERSION {{.*}}
 // NORTTI-NOT:#define __GXX_RTTI
 // NORTTI:#define __STDC__ 1
 //
 // RUN: %clang_cc1 -triple arm-linux-androideabi -E -dM < /dev/null | FileCheck -match-full-lines -check-prefix ANDROID %s
+// ANDROID-NOT:#define __ANDROID_API__
 // ANDROID:#define __ANDROID__ 1
 //
 // RUN: %clang_cc1 -x c++ -triple i686-linux-android -E -dM < /dev/null | FileCheck -match-full-lines -check-prefix I386-ANDROID-CXX %s
 // I386-ANDROID-CXX:#define __STDCPP_DEFAULT_NEW_ALIGNMENT__ 4U
 //
 // RUN: %clang_cc1 -x c++ -triple x86_64-linux-android -E -dM < /dev/null | FileCheck -match-full-lines -check-prefix X86_64-ANDROID-CXX %s
 // X86_64-ANDROID-CXX:#define __STDCPP_DEFAULT_NEW_ALIGNMENT__ 16UL
 //
+// RUN: %clang_cc1 -triple arm-linux-androideabi20 -E -dM < /dev/null | FileCheck -match-full-lines -check-prefix ANDROID20 %s
+// ANDROID20:#define __ANDROID_API__ 20
+// ANDROID20:#define __ANDROID__ 1
+//
 // RUN: %clang_cc1 -triple lanai-unknown-unknown -E -dM < /dev/null | FileCheck -match-full-lines -check-prefix LANAI %s
 // LANAI: #define __lanai__ 1
 //
 // RUN: %clang_cc1 -E -dM -ffreestanding -triple=amd64-unknown-openbsd6.1 < /dev/null | FileCheck -match-full-lines -check-prefix OPENBSD %s
 // RUN: %clang_cc1 -E -dM -ffreestanding -triple=arm-unknown-openbsd6.1-gnueabi < /dev/null | FileCheck -match-full-lines -check-prefix OPENBSD %s
 // RUN: %clang_cc1 -E -dM -ffreestanding -triple=i386-unknown-openbsd6.1 < /dev/null | FileCheck -match-full-lines -check-prefix OPENBSD %s
 // RUN: %clang_cc1 -E -dM -ffreestanding -triple=sparc64-unknown-openbsd6.1 < /dev/null | FileCheck -match-full-lines -check-prefix OPENBSD %s
 // OPENBSD:#define __ELF__ 1