Use a more C99-compliant function cast

4 files changed, 48 insertions, 4 deletions

diff --git a/examples/alconvolve.c b/examples/alconvolve.c
index d719abdb..8979e7a3 100644
--- a/examples/alconvolve.c
+++ b/examples/alconvolve.c
@@ -84,6 +84,17 @@ static LPALGETAUXILIARYEFFECTSLOTIV alGetAuxiliaryEffectSlotiv;
 static LPALGETAUXILIARYEFFECTSLOTF alGetAuxiliaryEffectSlotf;
 static LPALGETAUXILIARYEFFECTSLOTFV alGetAuxiliaryEffectSlotfv;
 
+/* C doesn't allow casting between function and non-function pointer types, so
+ * with C99 we need to use a union to reinterpret the pointer type. Pre-C99
+ * still needs to use a normal cast and live with the warning (C++ is fine with
+ * a regular reinterpret_cast).
+ */
+#if __STDC_VERSION__ >= 199901L
+#define FUNCTION_CAST(T, ptr) (union{void *p; T f;}){ptr}.f
+#else
+#define FUNCTION_CAST(T, ptr) (T)(ptr)
+#endif
+
 
 /* This stuff defines a simple streaming player object, the same as alstream.c.
  * Comments are removed for brevity, see alstream.c for more details.
@@ -438,7 +449,7 @@ int main(int argc, char **argv)
     }
 
     /* Define a macro to help load the function pointers. */
-#define LOAD_PROC(T, x)  ((x) = (T)alGetProcAddress(#x))
+#define LOAD_PROC(T, x)  ((x) = FUNCTION_CAST(T, alGetProcAddress(#x)))
     LOAD_PROC(LPALGENFILTERS, alGenFilters);
     LOAD_PROC(LPALDELETEFILTERS, alDeleteFilters);
     LOAD_PROC(LPALISFILTER, alIsFilter);
diff --git a/examples/allatency.c b/examples/allatency.c
index 5aa9e864..3b141ac0 100644
--- a/examples/allatency.c
+++ b/examples/allatency.c
@@ -51,6 +51,17 @@ static LPALGETSOURCEI64SOFT alGetSourcei64SOFT;
 static LPALGETSOURCE3I64SOFT alGetSource3i64SOFT;
 static LPALGETSOURCEI64VSOFT alGetSourcei64vSOFT;
 
+/* C doesn't allow casting between function and non-function pointer types, so
+ * with C99 we need to use a union to reinterpret the pointer type. Pre-C99
+ * still needs to use a normal cast and live with the warning (C++ is fine with
+ * a regular reinterpret_cast).
+ */
+#if __STDC_VERSION__ >= 199901L
+#define FUNCTION_CAST(T, ptr) (union{void *p; T f;}){ptr}.f
+#else
+#define FUNCTION_CAST(T, ptr) (T)(ptr)
+#endif
+
 /* LoadBuffer loads the named audio file into an OpenAL buffer object, and
  * returns the new buffer ID.
  */
@@ -164,7 +175,7 @@ int main(int argc, char **argv)
     }
 
     /* Define a macro to help load the function pointers. */
-#define LOAD_PROC(T, x)  ((x) = (T)alGetProcAddress(#x))
+#define LOAD_PROC(T, x)  ((x) = FUNCTION_CAST(T, alGetProcAddress(#x)))
     LOAD_PROC(LPALSOURCEDSOFT, alSourcedSOFT);
     LOAD_PROC(LPALSOURCE3DSOFT, alSource3dSOFT);
     LOAD_PROC(LPALSOURCEDVSOFT, alSourcedvSOFT);
diff --git a/examples/almultireverb.c b/examples/almultireverb.c
index eb874061..447216d1 100644
--- a/examples/almultireverb.c
+++ b/examples/almultireverb.c
@@ -92,6 +92,17 @@ static LPALGETAUXILIARYEFFECTSLOTIV alGetAuxiliaryEffectSlotiv;
 static LPALGETAUXILIARYEFFECTSLOTF alGetAuxiliaryEffectSlotf;
 static LPALGETAUXILIARYEFFECTSLOTFV alGetAuxiliaryEffectSlotfv;
 
+/* C doesn't allow casting between function and non-function pointer types, so
+ * with C99 we need to use a union to reinterpret the pointer type. Pre-C99
+ * still needs to use a normal cast and live with the warning (C++ is fine with
+ * a regular reinterpret_cast).
+ */
+#if __STDC_VERSION__ >= 199901L
+#define FUNCTION_CAST(T, ptr) (union{void *p; T f;}){ptr}.f
+#else
+#define FUNCTION_CAST(T, ptr) (T)(ptr)
+#endif
+
 
 /* LoadEffect loads the given initial reverb properties into the given OpenAL
  * effect object, and returns non-zero on success.
@@ -519,7 +530,7 @@ int main(int argc, char **argv)
     }
 
     /* Define a macro to help load the function pointers. */
-#define LOAD_PROC(T, x)  ((x) = (T)alGetProcAddress(#x))
+#define LOAD_PROC(T, x)  ((x) = FUNCTION_CAST(T, alGetProcAddress(#x)))
     LOAD_PROC(LPALGENFILTERS, alGenFilters);
     LOAD_PROC(LPALDELETEFILTERS, alDeleteFilters);
     LOAD_PROC(LPALISFILTER, alIsFilter);
diff --git a/examples/alreverb.c b/examples/alreverb.c
index 56acdd82..0d62e210 100644
--- a/examples/alreverb.c
+++ b/examples/alreverb.c
@@ -67,6 +67,17 @@ static LPALGETAUXILIARYEFFECTSLOTIV alGetAuxiliaryEffectSlotiv;
 static LPALGETAUXILIARYEFFECTSLOTF alGetAuxiliaryEffectSlotf;
 static LPALGETAUXILIARYEFFECTSLOTFV alGetAuxiliaryEffectSlotfv;
 
+/* C doesn't allow casting between function and non-function pointer types, so
+ * with C99 we need to use a union to reinterpret the pointer type. Pre-C99
+ * still needs to use a normal cast and live with the warning (C++ is fine with
+ * a regular reinterpret_cast).
+ */
+#if __STDC_VERSION__ >= 199901L
+#define FUNCTION_CAST(T, ptr) (union{void *p; T f;}){ptr}.f
+#else
+#define FUNCTION_CAST(T, ptr) (T)(ptr)
+#endif
+
 
 /* LoadEffect loads the given reverb properties into a new OpenAL effect
  * object, and returns the new effect ID. */
@@ -259,7 +270,7 @@ int main(int argc, char **argv)
     }
 
     /* Define a macro to help load the function pointers. */
-#define LOAD_PROC(T, x)  ((x) = (T)alGetProcAddress(#x))
+#define LOAD_PROC(T, x)  ((x) = FUNCTION_CAST(T, alGetProcAddress(#x)))
     LOAD_PROC(LPALGENEFFECTS, alGenEffects);
     LOAD_PROC(LPALDELETEEFFECTS, alDeleteEffects);
     LOAD_PROC(LPALISEFFECT, alIsEffect);