Enable "-Wundefined-reinterpret-cast".

A couple cases popped up where we were using an undefined cast.
Fix them by rearranging assignment macros to use decltype.

Another warning that is enabled in Skia.

Bug: angleproject:4046
Change-Id: Ibdbae0b2a96909b101a259ff805b8b2d43a5174b
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1877479
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>

BUILD.gn

@@ -144,6 +144,7 @@ config("extra_warnings") {
       "-Wredundant-parens",
       "-Wshadow-field",
       "-Wtautological-type-limit-compare",
+      "-Wundefined-reinterpret-cast",
       "-Wunneeded-internal-declaration",
 
       # The below warnings are used by WebKit. We enable them to make rolling

scripts/code_generation_hashes/OpenGL_dispatch_table.json

@@ -4,11 +4,11 @@
   "src/libANGLE/renderer/angle_format.py":
     "32ba71942c0fd00e6807104f1bb80a3c",
   "src/libANGLE/renderer/gl/DispatchTableGL_autogen.cpp":
-    "7ebaa7f7525a0fe13f163ec076a8eace",
+    "ea253c245e64fd67c55904fd28173997",
   "src/libANGLE/renderer/gl/DispatchTableGL_autogen.h":
     "27af4da77c5cc60708fd2aabedc983f7",
   "src/libANGLE/renderer/gl/generate_gl_dispatch_table.py":
-    "f21314d401e650b4182c4b7d66ac5c9c",
+    "4f19a7eee17679b3a0ad4abad6fab2c9",
   "src/libANGLE/renderer/gl/gl_bindings_data.json":
     "e870a4d86dc69e52dcab9afd78a47c9b",
   "src/libANGLE/renderer/gl/null_functions.cpp":

src/libANGLE/renderer/gl/DispatchTableGL_autogen.cpp

@@ -20,7 +20,7 @@
 // Check for nullptr so extensions do not overwrite core imports.
 #define ASSIGN(NAME, FP) \
     if (!FP)             \
-    *reinterpret_cast<void **>(&FP) = loadProcAddress(NAME)
+    FP = reinterpret_cast<decltype(FP)>(loadProcAddress(NAME))
 
 namespace rx
 {

src/libANGLE/renderer/gl/FunctionsGL.cpp

@@ -93,7 +93,7 @@ static void INTERNAL_GL_APIENTRY DummyGetShaderiv(GLuint program, GLenum pname,
 }
 #endif  // defined(ANGLE_ENABLE_OPENGL_NULL)
 
-#define ASSIGN(NAME, FP) *reinterpret_cast<void **>(&FP) = loadProcAddress(NAME)
+#define ASSIGN(NAME, FP) FP = reinterpret_cast<decltype(FP)>(loadProcAddress(NAME))
 
 FunctionsGL::FunctionsGL() : version(), standard(), extensions() {}
 

src/libANGLE/renderer/gl/generate_gl_dispatch_table.py

@@ -111,7 +111,7 @@ dispatch_table_source_template = """// GENERATED FILE - DO NOT EDIT.
 #endif  // defined(ANGLE_ENABLE_OPENGL_NULL)
 
 // Check for nullptr so extensions do not overwrite core imports.
-#define ASSIGN(NAME, FP) if (!FP) *reinterpret_cast<void **>(&FP) = loadProcAddress(NAME)
+#define ASSIGN(NAME, FP) if (!FP) FP = reinterpret_cast<decltype(FP)>(loadProcAddress(NAME))
 
 namespace rx
 {{