check for unistd.h during CMake or with more-compatible checks

Author: QuietMisdreavus

extensions/CMakeLists.txt

@@ -98,14 +98,10 @@ include(CheckIncludeFile)
 include(CheckCSourceCompiles)
 include(CheckCSourceRuns)
 include(CheckSymbolExists)
-CHECK_INCLUDE_FILE(stdbool.h HAVE_STDBOOL_H)
+CHECK_INCLUDE_FILE(unistd.h HAVE_UNISTD_H)
 CHECK_C_SOURCE_COMPILES(
   "int main() { __builtin_expect(0,0); return 0; }"
   HAVE___BUILTIN_EXPECT)
-CHECK_C_SOURCE_COMPILES("
-  int f(void) __attribute__ (());
-  int main() { return 0; }
-" HAVE___ATTRIBUTE__)
 
 # Always compile with warnings
 if(MSVC)

src/CMakeLists.txt

@@ -178,6 +178,7 @@ include(CheckIncludeFile)
 include(CheckCSourceCompiles)
 include(CheckCSourceRuns)
 include(CheckSymbolExists)
+CHECK_INCLUDE_FILE(unistd.h HAVE_UNISTD_H)
 CHECK_C_SOURCE_COMPILES(
   "int main() { __builtin_expect(0,0); return 0; }"
   HAVE___BUILTIN_EXPECT)

src/config.h.in

@@ -11,6 +11,8 @@ extern "C" {
   typedef char bool;
 #endif
 
+#cmakedefine HAVE_UNISTD_H
+
 #cmakedefine HAVE___BUILTIN_EXPECT
 
 #cmakedefine CMARK_THREADING

src/include/cmark-gfm_config.h

@@ -15,6 +15,15 @@ extern "C" {
   typedef char bool;
 #endif
 
+#if defined(__has_include)
+#  if __has_include(<unistd.h>)
+#    define HAVE_UNISTD_H
+#  endif
+#elif defined(unix) || defined(__unix__) || defined(__unix) || defined(__APPLE__)
+  // Apple Clang does not define any of the unix symbols, even though it provides unistd.h
+#  define HAVE_UNISTD_H
+#endif
+
 #define HAVE___BUILTIN_EXPECT
 
 #define CMARK_THREADING

src/include/mutex.h

@@ -5,7 +5,7 @@
 
 #ifdef CMARK_THREADING
 
-#if __has_include(<unistd.h>)
+#ifdef HAVE_UNISTD_H
 #include <unistd.h>
 #endif