Use SDL_DISABLE_ALLOCA instead of HAVE_ALLOCA in SDL_stdinc.h

include/SDL3/SDL_stdinc.h

@@ -37,26 +37,28 @@
 #include <stdint.h>
 #include <wchar.h>
 
-#ifndef alloca
-# ifdef HAVE_ALLOCA_H
-#  include <alloca.h>
-# elif defined(__GNUC__)
-#  define alloca __builtin_alloca
-# elif defined(_MSC_VER)
-#  include <malloc.h>
-#  define alloca _alloca
-# elif defined(__WATCOMC__)
-#  include <malloc.h>
-# elif defined(__BORLANDC__)
-#  include <malloc.h>
-# elif defined(__DMC__)
-#  include <stdlib.h>
-# elif defined(__AIX__)
-#pragma alloca
-# elif defined(__MRC__)
+#ifndef SDL_DISABLE_ALLOCA
+# ifndef alloca
+#  ifdef HAVE_ALLOCA_H
+#   include <alloca.h>
+#  elif defined(__GNUC__)
+#   define alloca __builtin_alloca
+#  elif defined(_MSC_VER)
+#   include <malloc.h>
+#   define alloca _alloca
+#  elif defined(__WATCOMC__)
+#   include <malloc.h>
+#  elif defined(__BORLANDC__)
+#   include <malloc.h>
+#  elif defined(__DMC__)
+#   include <stdlib.h>
+#  elif defined(__AIX__)
+# pragma alloca
+#  elif defined(__MRC__)
 void *alloca(unsigned);
-# else
+#  else
 char *alloca();
+#  endif
 # endif
 #endif
 
@@ -379,7 +381,7 @@ SDL_COMPILE_TIME_ASSERT(enum, sizeof(SDL_DUMMY_ENUM) == sizeof(int));
 extern "C" {
 #endif
 
-#ifdef HAVE_ALLOCA
+#ifndef SDL_DISABLE_ALLOCA
 #define SDL_stack_alloc(type, count)    (type*)alloca(sizeof(type)*(count))
 #define SDL_stack_free(data)
 #else

include/build_config/SDL_build_config.h.cmake

@@ -42,6 +42,8 @@
 #cmakedefine HAVE_GCC_ATOMICS @HAVE_GCC_ATOMICS@
 #cmakedefine HAVE_GCC_SYNC_LOCK_TEST_AND_SET @HAVE_GCC_SYNC_LOCK_TEST_AND_SET@
 
+#cmakedefine SDL_DISABLE_ALLOCA
+
 /* Comment this if you want to build without any C library requirements */
 #cmakedefine HAVE_LIBC 1
 #ifdef HAVE_LIBC
@@ -74,7 +76,6 @@
 #cmakedefine HAVE_CALLOC 1
 #cmakedefine HAVE_REALLOC 1
 #cmakedefine HAVE_FREE 1
-#cmakedefine HAVE_ALLOCA 1
 #ifndef __WIN32__ /* Don't use C runtime versions of these on Windows */
 #cmakedefine HAVE_GETENV 1
 #cmakedefine HAVE_SETENV 1

include/build_config/SDL_build_config_android.h

@@ -57,7 +57,6 @@
 #define HAVE_CALLOC 1
 #define HAVE_REALLOC    1
 #define HAVE_FREE   1
-#define HAVE_ALLOCA 1
 #define HAVE_GETENV 1
 #define HAVE_SETENV 1
 #define HAVE_PUTENV 1

include/build_config/SDL_build_config_emscripten.h

@@ -60,7 +60,6 @@
 #define HAVE_CALLOC 1
 #define HAVE_REALLOC 1
 #define HAVE_FREE 1
-#define HAVE_ALLOCA 1
 #define HAVE_GETENV 1
 #define HAVE_SETENV 1
 #define HAVE_PUTENV 1

include/build_config/SDL_build_config_ios.h

@@ -49,7 +49,6 @@
 #define HAVE_CALLOC 1
 #define HAVE_REALLOC    1
 #define HAVE_FREE   1
-#define HAVE_ALLOCA 1
 #define HAVE_GETENV 1
 #define HAVE_SETENV 1
 #define HAVE_PUTENV 1

include/build_config/SDL_build_config_macos.h

@@ -54,7 +54,6 @@
 #define HAVE_CALLOC 1
 #define HAVE_REALLOC    1
 #define HAVE_FREE   1
-#define HAVE_ALLOCA 1
 #define HAVE_GETENV 1
 #define HAVE_SETENV 1
 #define HAVE_PUTENV 1

include/build_config/SDL_build_config_windows.h

@@ -131,7 +131,6 @@ typedef unsigned int uintptr_t;
 #define HAVE_CALLOC 1
 #define HAVE_REALLOC 1
 #define HAVE_FREE 1
-#define HAVE_ALLOCA 1
 #define HAVE_QSORT 1
 #define HAVE_BSEARCH 1
 #define HAVE_ABS 1

include/build_config/SDL_build_config_wingdk.h

@@ -77,7 +77,6 @@
 #define HAVE_CALLOC 1
 #define HAVE_REALLOC 1
 #define HAVE_FREE 1
-#define HAVE_ALLOCA 1
 #define HAVE_QSORT 1
 #define HAVE_BSEARCH 1
 #define HAVE_ABS 1

include/build_config/SDL_build_config_winrt.h

@@ -75,7 +75,6 @@
 #define HAVE_CALLOC 1
 #define HAVE_REALLOC 1
 #define HAVE_FREE 1
-#define HAVE_ALLOCA 1
 #define HAVE_QSORT 1
 #define HAVE_BSEARCH 1
 #define HAVE_ABS 1

include/build_config/SDL_build_config_xbox.h

@@ -77,7 +77,6 @@
 #define HAVE_CALLOC 1
 #define HAVE_REALLOC 1
 #define HAVE_FREE 1
-#define HAVE_ALLOCA 1
 #define HAVE_QSORT 1
 #define HAVE_BSEARCH 1
 #define HAVE_ABS 1