From 92ba53599931fcbe31e7970497cb9e60091434c1 Mon Sep 17 00:00:00 2001
From: Abseil Team <absl-team@google.com>
Date: Thu, 7 Jan 2021 06:10:17 -0800
Subject: Export of internal Abseil changes

--
e86453648e05d9bf30ff97a68fba8ce5134ee1c9 by Abseil Team <absl-team@google.com>:

Fix compilation in C with clang on windows with -Wundef flag

PiperOrigin-RevId: 350545275
GitOrigin-RevId: e86453648e05d9bf30ff97a68fba8ce5134ee1c9
Change-Id: I029538298ff894d5798b9c6f488af7aa1a3ec2a7
---
 absl/base/config.h | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/absl/base/config.h b/absl/base/config.h
index 3f7f32b9..c9a06f1d 100644
--- a/absl/base/config.h
+++ b/absl/base/config.h
@@ -490,7 +490,7 @@ static_assert(ABSL_INTERNAL_INLINE_NAMESPACE_STR[0] != 'h' ||
 #endif
 
 #ifdef __has_include
-#if __has_include(<any>) && __cplusplus >= 201703L && \
+#if __has_include(<any>) && defined(__cplusplus) && __cplusplus >= 201703L && \
     !ABSL_INTERNAL_APPLE_CXX17_TYPES_UNAVAILABLE
 #define ABSL_HAVE_STD_ANY 1
 #endif
@@ -504,8 +504,8 @@ static_assert(ABSL_INTERNAL_INLINE_NAMESPACE_STR[0] != 'h' ||
 #endif
 
 #ifdef __has_include
-#if __has_include(<optional>) && __cplusplus >= 201703L && \
-    !ABSL_INTERNAL_APPLE_CXX17_TYPES_UNAVAILABLE
+#if __has_include(<optional>) && defined(__cplusplus) && \
+    __cplusplus >= 201703L && !ABSL_INTERNAL_APPLE_CXX17_TYPES_UNAVAILABLE
 #define ABSL_HAVE_STD_OPTIONAL 1
 #endif
 #endif
@@ -518,8 +518,8 @@ static_assert(ABSL_INTERNAL_INLINE_NAMESPACE_STR[0] != 'h' ||
 #endif
 
 #ifdef __has_include
-#if __has_include(<variant>) && __cplusplus >= 201703L && \
-    !ABSL_INTERNAL_APPLE_CXX17_TYPES_UNAVAILABLE
+#if __has_include(<variant>) && defined(__cplusplus) && \
+    __cplusplus >= 201703L && !ABSL_INTERNAL_APPLE_CXX17_TYPES_UNAVAILABLE
 #define ABSL_HAVE_STD_VARIANT 1
 #endif
 #endif
@@ -532,7 +532,8 @@ static_assert(ABSL_INTERNAL_INLINE_NAMESPACE_STR[0] != 'h' ||
 #endif
 
 #ifdef __has_include
-#if __has_include(<string_view>) && __cplusplus >= 201703L
+#if __has_include(<string_view>) && defined(__cplusplus) && \
+    __cplusplus >= 201703L
 #define ABSL_HAVE_STD_STRING_VIEW 1
 #endif
 #endif
@@ -544,8 +545,9 @@ static_assert(ABSL_INTERNAL_INLINE_NAMESPACE_STR[0] != 'h' ||
 // not correctly set by MSVC, so we use `_MSVC_LANG` to check the language
 // version.
 // TODO(zhangxy): fix tests before enabling aliasing for `std::any`.
-#if defined(_MSC_VER) && _MSC_VER >= 1910 && \
-    ((defined(_MSVC_LANG) && _MSVC_LANG > 201402) || __cplusplus > 201402)
+#if defined(_MSC_VER) && _MSC_VER >= 1910 &&         \
+    ((defined(_MSVC_LANG) && _MSVC_LANG > 201402) || \
+     (defined(__cplusplus) && __cplusplus > 201402))
 // #define ABSL_HAVE_STD_ANY 1
 #define ABSL_HAVE_STD_OPTIONAL 1
 #define ABSL_HAVE_STD_VARIANT 1
-- 
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