[clang] Extend clang's <limits.h> to define *LONG_LONG*_ macros for b…

…ionic (#115406)

*LONG_LONG*_ macros are not GNU-only extensions any more. Bionic also
defines them.

clang/docs/ReleaseNotes.rst

@@ -271,6 +271,8 @@ Resolutions to C++ Defect Reports
 C Language Changes
 ------------------
 
+- Extend clang's ``<limits.h>`` to define ``LONG_LONG_*`` macros for Android's bionic.
+
 C2y Feature Support
 ^^^^^^^^^^^^^^^^^^^
 

clang/lib/Headers/limits.h

@@ -111,11 +111,14 @@
 #define ULLONG_MAX (__LONG_LONG_MAX__*2ULL+1ULL)
 #endif
 
-/* LONG_LONG_MIN/LONG_LONG_MAX/ULONG_LONG_MAX are a GNU extension.  It's too bad
-   that we don't have something like #pragma poison that could be used to
-   deprecate a macro - the code should just use LLONG_MAX and friends.
+/* LONG_LONG_MIN/LONG_LONG_MAX/ULONG_LONG_MAX are a GNU extension. Android's
+   bionic also defines them. It's too bad that we don't have something like
+   #pragma poison that could be used to deprecate a macro - the code should just
+   use LLONG_MAX and friends.
  */
-#if defined(__GNU_LIBRARY__) ? defined(__USE_GNU) : !defined(__STRICT_ANSI__)
+#if (defined(__GNU_LIBRARY__) ? defined(__USE_GNU)                             \
+                              : !defined(__STRICT_ANSI__)) ||                  \
+    defined(__BIONIC__)
 
 #undef   LONG_LONG_MIN
 #undef   LONG_LONG_MAX

clang/test/Headers/limits.cpp

@@ -4,6 +4,9 @@
 // RUN: %clang_cc1 -std=c17 -ffreestanding -fsyntax-only -verify -x c %s
 // RUN: %clang_cc1 -std=c2x -ffreestanding -fsyntax-only -verify -x c %s
 
+// Specifically test arm64 linux platforms.
+// RUN: %clang_cc1 -triple arm64-linux -ffreestanding -fsyntax-only -verify -x c %s
+
 // Specifically test 16-bit int platforms.
 // RUN: %clang_cc1 -triple=avr -ffreestanding -fsyntax-only -verify -x c %s
 // RUN: %clang_cc1 -triple=avr -std=c++11 -ffreestanding -fsyntax-only -verify %s