Build: Clean up inline keyword detection

Strict C89-conformant compilers don't support the "inline" keyword, but
most of them support "__inline__", and that keyword can be used with the
always_inline atribute as well.  This commit also removes duplicate code
by using a foreach() loop to test the various keywords.

diff --git a/CMakeLists.txt b/CMakeLists.txt
index c57a2437b5d6477717f8694fa428b1fc9c221da2..b0cd72e9a617995b10515e522724ea6d2fda5689 100644 (file)
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -420,37 +420,31 @@ if(UNIX)
   endif()
 endif()
 
+if(MSVC)
+  set(INLINE_OPTIONS "__inline;inline")
+else()
+  set(INLINE_OPTIONS "__inline__;inline")
+endif()
 option(FORCE_INLINE "Force function inlining" TRUE)
 boolean_number(FORCE_INLINE)
 if(FORCE_INLINE)
   if(MSVC)
-    set(INLINE "__forceinline")
-    check_c_source_compiles("__forceinline void foo(void) {} int main(void) { foo(); }"
-      FORCE_INLINE_WORKS)
+    list(INSERT INLINE_OPTIONS 0 "__forceinline")
   else()
-    set(INLINE "inline __attribute__((always_inline))")
-    check_c_source_compiles("static inline __attribute__((always_inline)) void foo(void) {} int main(void) { foo(); }"
-      FORCE_INLINE_WORKS)
+    list(INSERT INLINE_OPTIONS 0 "inline __attribute__((always_inline))")
+    list(INSERT INLINE_OPTIONS 0 "__inline__ __attribute__((always_inline))")
   endif()
 endif()
-if(NOT FORCE_INLINE OR NOT FORCE_INLINE_WORKS)
-  if(MSVC)
-    set(INLINE "__inline")
-    check_c_source_compiles("__inline void foo(void) {} int main(void) { foo(); }"
-      INLINE_WORKS)
-  else()
-    set(INLINE "__inline__")
-    check_c_source_compiles("static __inline__ void foo(void) {} int main(void) { foo(); }"
-      INLINE_WORKS)
-  endif()
-  if(NOT INLINE_WORKS)
-    set(INLINE "inline")
-    check_c_source_compiles("static inline void foo(void) {} int main(void) { foo(); }"
-      C99_INLINE_WORKS)
-    if(NOT C99_INLINE_WORKS)
-      message(FATAL_ERROR "Could not determine how to inline functions.")
-    endif()
+foreach(inline ${INLINE_OPTIONS})
+  check_c_source_compiles("${inline} static void foo(void) {} int main(void) { foo(); }"
+    INLINE_WORKS)
+  if(INLINE_WORKS)
+    set(INLINE ${inline})
+    break()
   endif()
+endforeach()
+if(NOT INLINE_WORKS)
+  message(FATAL_ERROR "Could not determine how to inline functions.")
 endif()
 message(STATUS "INLINE = ${INLINE} (FORCE_INLINE = ${FORCE_INLINE})")