emacs-macport: use a different hammer for the CF_NOESCAPE bug

The header was breaking compilation with modern versions of Clang,
seemingly due to the `limits.h` stuff. Wrapping the header directly
is simpler and fixes it.

pkgs/applications/editors/emacs/macport-noescape-noop/CoreFoundation/CFBase.h

@@ -0,0 +1,8 @@
+#if !defined(__COREFOUNDATION_CFBASE__)
+
+#include_next <CoreFoundation/CFBase.h>
+
+#undef CF_NOESCAPE
+#define CF_NOESCAPE
+
+#endif

pkgs/applications/editors/emacs/macport_noescape_noop.h

@@ -1,31 +0,0 @@
-#ifndef NOESCAPE_NOOP_H_
-#define NOESCAPE_NOOP_H_
-
-// First, do some work to get definitions for *_WIDTH. Normally, Emacs would
-// have these defined by headers in-tree, but clang's headers clash with those.
-// Due to how include paths work, we have to include clang headers if we want to
-// mess with CoreFoundation definitions.
-#pragma push_macro("__STDC_VERSION__")
-// Make the preprocessor think that we're on C2x. The macros we want are gated
-// on it.
-#undef __STDC_VERSION__
-#define __STDC_VERSION__ 202000L
-// Include limits.h first, as stdint.h includes it.
-#include <limits.h>
-
-// XX: clang's stdint.h is shy and won't give us its defs unless it thinks it's
-// in freestanding mode.
-#undef __STDC_HOSTED__
-#include <stdint.h>
-#define __STDC_HOSTED__ 1
-
-#pragma pop_macro("__STDC_VERSION__")
-
-// Now, pull in the header that defines CF_NOESCAPE.
-#include <CoreFoundation/CFBase.h>
-
-// Redefine CF_NOESCAPE as empty.
-#undef CF_NOESCAPE
-#define CF_NOESCAPE
-
-#endif // NOESCAPE_NOOP_H_

pkgs/applications/editors/emacs/make-emacs.nix

@@ -45,7 +45,6 @@
   libtiff,
   libwebp,
   libxml2,
-  llvmPackages_14,
   m17n_lib,
   mailcap,
   mailutils,
@@ -139,12 +138,8 @@ let
   ++ lib.optionals (stdenv.cc ? cc.lib.libgcc) [
     "${lib.getLib stdenv.cc.cc.lib.libgcc}/lib"
   ];
-
-  inherit (if variant == "macport" then llvmPackages_14.stdenv else stdenv)
-    mkDerivation
-    ;
 in
-mkDerivation (finalAttrs: {
+stdenv.mkDerivation (finalAttrs: {
   pname =
     pname
     + (
@@ -430,7 +425,7 @@ mkDerivation (finalAttrs: {
     // lib.optionalAttrs (variant == "macport") {
       # Fixes intermittent segfaults when compiled with LLVM >= 7.0.
       # See https://github.com/NixOS/nixpkgs/issues/127902
-      NIX_CFLAGS_COMPILE = "-include ${./macport_noescape_noop.h}";
+      NIX_CFLAGS_COMPILE = "-isystem ${./macport-noescape-noop}";
     };
 
   enableParallelBuilding = true;