[Runtime] Avoid referring to enum _dyld_section_location_kind.

If the SDK has dyld_priv.h but doesn't have enum _dyld_section_location_kind, we can't use enum _dyld_section_location_kind and it's hard to detect that. Instead, just use `int`, and use #defines for the values.

Author: mikeash

stdlib/public/runtime/ImageInspectionMachO.cpp

@@ -33,22 +33,17 @@
 #if __has_include(<objc/objc-internal.h>) && __has_include(<mach-o/dyld_priv.h>)
 #include <mach-o/dyld_priv.h>
 #include <objc/objc-internal.h>
-#else
-
-// Bring our own definition of enum _dyld_section_location_kind and some of its
-// values. They'll be unused when we can't include dyld_priv.h, but the code
-// needs them in order to compile.
-enum _dyld_section_location_kind {
-  _dyld_section_location_text_swift5_protos,
-  _dyld_section_location_text_swift5_proto,
-  _dyld_section_location_text_swift5_types,
-  _dyld_section_location_text_swift5_replace,
-  _dyld_section_location_text_swift5_replace2,
-  _dyld_section_location_text_swift5_ac_funcs,
-};
-
 #endif
 
+// Bring our own definition of _dyld_section_location constants in case we're
+// using an older SDK that doesn't have them.
+#define _dyld_section_location_text_swift5_protos 0
+#define _dyld_section_location_text_swift5_proto 1
+#define _dyld_section_location_text_swift5_types 2
+#define _dyld_section_location_text_swift5_replace 3
+#define _dyld_section_location_text_swift5_replace2 4
+#define _dyld_section_location_text_swift5_ac_funcs 5
+
 #if !OBJC_ADDLOADIMAGEFUNC2_DEFINED
 // If we don't have objc_addLoadImageFunc2, fall back to objc_addLoadImageFunc.
 // Use a #define so we don't have to conditionalize the calling code below.
@@ -79,8 +74,7 @@ using mach_header_platform = mach_header;
 #endif
 
 // Callback for objc_addLoadImageFunc that just takes a mach_header.
-template <const char *SEGMENT_NAME, const char *SECTION_NAME,
-          enum _dyld_section_location_kind SECTION_KIND,
+template <const char *SEGMENT_NAME, const char *SECTION_NAME, int SECTION_KIND,
           void CONSUME_BLOCK(const void *baseAddress, const void *start,
                              uintptr_t size)>
 void addImageCallback(const mach_header *mh) {
@@ -102,8 +96,7 @@ void addImageCallback(const mach_header *mh) {
 
 // Callback for objc_addLoadImageFunc2 that takes a mach_header and dyld info.
 #if OBJC_ADDLOADIMAGEFUNC2_DEFINED
-template <const char *SEGMENT_NAME, const char *SECTION_NAME,
-          enum _dyld_section_location_kind SECTION_KIND,
+template <const char *SEGMENT_NAME, const char *SECTION_NAME, int SECTION_KIND,
           void CONSUME_BLOCK(const void *baseAddress, const void *start,
                              uintptr_t size)>
 void addImageCallback(const mach_header *mh,
@@ -112,16 +105,17 @@ void addImageCallback(const mach_header *mh,
   assert(mh->magic == MH_MAGIC_64 && "loaded non-64-bit image?!");
 #endif
 
-  auto result = _dyld_lookup_section_info(mh, dyldInfo, SECTION_KIND);
+  auto result = _dyld_lookup_section_info(
+      mh, dyldInfo,
+      static_cast<enum _dyld_section_location_kind>(SECTION_KIND));
   if (result.buffer)
     CONSUME_BLOCK(mh, result.buffer, result.bufferSize);
 }
 #endif
 
 // Callback for _dyld_register_func_for_add_image that takes a mach_header and a
 // slide.
-template <const char *SEGMENT_NAME, const char *SECTION_NAME,
-          enum _dyld_section_location_kind SECTION_KIND,
+template <const char *SEGMENT_NAME, const char *SECTION_NAME, int SECTION_KIND,
           void CONSUME_BLOCK(const void *baseAddress, const void *start,
                              uintptr_t size)>
 void addImageCallback(const mach_header *mh, intptr_t vmaddr_slide) {
@@ -132,11 +126,10 @@ void addImageCallback(const mach_header *mh, intptr_t vmaddr_slide) {
 
 template <const char *SEGMENT_NAME, const char *SECTION_NAME,
           const char *SEGMENT_NAME2, const char *SECTION_NAME2,
-          enum _dyld_section_location_kind SECTION_KIND,
-          enum _dyld_section_location_kind SECTION_KIND2,
-          void CONSUME_BLOCK(const void *baseAddress,
-                             const void *start, uintptr_t size,
-                             const void *start2, uintptr_t size2)>
+          int SECTION_KIND, int SECTION_KIND2,
+          void CONSUME_BLOCK(const void *baseAddress, const void *start,
+                             uintptr_t size, const void *start2,
+                             uintptr_t size2)>
 void addImageCallback2Sections(const mach_header *mh) {
 #if __POINTER_WIDTH__ == 64
   assert(mh->magic == MH_MAGIC_64 && "loaded non-64-bit image?!");
@@ -168,23 +161,26 @@ void addImageCallback2Sections(const mach_header *mh) {
 #if OBJC_ADDLOADIMAGEFUNC2_DEFINED
 template <const char *SEGMENT_NAME, const char *SECTION_NAME,
           const char *SEGMENT_NAME2, const char *SECTION_NAME2,
-          enum _dyld_section_location_kind SECTION_KIND,
-          enum _dyld_section_location_kind SECTION_KIND2,
-          void CONSUME_BLOCK(const void *baseAddress,
-                             const void *start, uintptr_t size,
-                             const void *start2, uintptr_t size2)>
+          int SECTION_KIND, int SECTION_KIND2,
+          void CONSUME_BLOCK(const void *baseAddress, const void *start,
+                             uintptr_t size, const void *start2,
+                             uintptr_t size2)>
 void addImageCallback2Sections(const mach_header *mh,
                                struct _dyld_section_location_info_s *dyldInfo) {
 #if __POINTER_WIDTH__ == 64
   assert(mh->magic == MH_MAGIC_64 && "loaded non-64-bit image?!");
 #endif
 
   // Look for a section.
-  auto result = _dyld_lookup_section_info(mh, dyldInfo, SECTION_KIND);
+  auto result = _dyld_lookup_section_info(
+      mh, dyldInfo,
+      static_cast<enum _dyld_section_location_kind>(SECTION_KIND));
   if (!result.buffer)
     return;
 
-  auto result2 = _dyld_lookup_section_info(mh, dyldInfo, SECTION_KIND2);
+  auto result2 = _dyld_lookup_section_info(
+      mh, dyldInfo,
+      static_cast<enum _dyld_section_location_kind>(SECTION_KIND2));
   // No NULL check here, we allow this one not to be present. dyld gives us
   // a NULL pointer and 0 size when the section isn't in the dylib so we don't
   // need to zero anything out.
@@ -198,8 +194,7 @@ void addImageCallback2Sections(const mach_header *mh,
 // slide.
 template <const char *SEGMENT_NAME, const char *SECTION_NAME,
           const char *SEGMENT_NAME2, const char *SECTION_NAME2,
-          enum _dyld_section_location_kind SECTION_KIND,
-          enum _dyld_section_location_kind SECTION_KIND2,
+          int SECTION_KIND, int SECTION_KIND2,
           void CONSUME_BLOCK(const void *baseAddress, const void *start,
                              uintptr_t size, const void *start2,
                              uintptr_t size2)>