bintools-wrapper, cc-wrapper: parameterize darwin min version variable

These variables are the ones that the standard toolchain uses, so we
should use those and not always use MACOSX_DEPLOYMENT_TARGET.

See 236a426c12/cctools/ld64/src/ld/PlatformSupport.cpp (L54-L55)

lib/systems/default.nix

@@ -120,6 +120,10 @@ rec {
       # platforms define the old name "sdkVer".
       darwinSdkVersion = final.sdkVer or "10.12";
       darwinMinVersion = final.darwinSdkVersion;
+      darwinMinVersionVariable =
+        if final.isMacOS then "MACOSX_DEPLOYMENT_TARGET"
+        else if final.isiOS then "IPHONEOS_DEPLOYMENT_TARGET"
+        else null;
 
       emulator = pkgs: let
         qemu-user = pkgs.qemu.override {

pkgs/build-support/bintools-wrapper/add-darwin-ldflags-before.sh

@@ -21,7 +21,7 @@ havePlatformVersionFlag=
 haveDarwinSDKVersion=
 haveDarwinPlatformVersion=
 
-mangleVarSingle MACOSX_DEPLOYMENT_TARGET ${role_suffixes[@]+"${role_suffixes[@]}"}
+mangleVarSingle @darwinMinVersionVariable@ ${role_suffixes[@]+"${role_suffixes[@]}"}
 
 n=0
 nParams=${#params[@]}
@@ -61,12 +61,12 @@ done
 if [ ! "$havePlatformVersionFlag" ]; then
     if [ ! "$haveDarwinSDKVersion" ] && [ ! "$haveDarwinPlatformVersion" ]; then
         # Nothing provided. Use the modern "-platform_version" to set both.
-        extraBefore+=(-platform_version @darwinPlatform@ "${MACOSX_DEPLOYMENT_TARGET_@suffixSalt@:-@darwinMinVersion@}" @darwinSdkVersion@)
+        extraBefore+=(-platform_version @darwinPlatform@ "${@darwinMinVersionVariable@_@suffixSalt@:-@darwinMinVersion@}" @darwinSdkVersion@)
     elif [ ! "$haveDarwinSDKVersion" ]; then
         # Add missing sdk version
         extraBefore+=(-sdk_version @darwinSdkVersion@)
     elif [ ! "$haveDarwinPlatformVersion" ]; then
         # Add missing platform version
-        extraBefore+=(-@darwinPlatform@_version_min "${MACOSX_DEPLOYMENT_TARGET_@suffixSalt@:-@darwinMinVersion@}")
+        extraBefore+=(-@darwinPlatform@_version_min "${@darwinMinVersionVariable@_@suffixSalt@:-@darwinMinVersion@}")
     fi
 fi

pkgs/build-support/bintools-wrapper/default.nix

@@ -327,11 +327,14 @@ stdenv.mkDerivation {
     ###
     + optionalString stdenv.targetPlatform.isDarwin (
       let
-        inherit (stdenv.targetPlatform) darwinMinVersion darwinPlatform darwinSdkVersion;
+        inherit (stdenv.targetPlatform)
+          darwinPlatform darwinSdkVersion
+          darwinMinVersion darwinMinVersionVariable;
       in ''
         export darwinPlatform=${darwinPlatform}
         export darwinMinVersion=${darwinMinVersion}
         export darwinSdkVersion=${darwinSdkVersion}
+        export darwinMinVersionVariable=${darwinMinVersionVariable}
         substituteAll ${./add-darwin-ldflags-before.sh} $out/nix-support/add-local-ldflags-before.sh
       ''
     )

pkgs/build-support/cc-wrapper/add-flags.sh

@@ -68,9 +68,9 @@ fi
 # Only add darwin min version flag if a default darwin min version is set,
 # which is a signal that we're targetting darwin.
 if [ "@darwinMinVersion@" ]; then
-    mangleVarSingle MACOSX_DEPLOYMENT_TARGET ${role_suffixes[@]+"${role_suffixes[@]}"}
+    mangleVarSingle @darwinMinVersionVariable@ ${role_suffixes[@]+"${role_suffixes[@]}"}
 
-    NIX_CFLAGS_COMPILE_BEFORE_@suffixSalt@="-m@darwinPlatformForCC@-version-min=${MACOSX_DEPLOYMENT_TARGET_@suffixSalt@:-@darwinMinVersion@} $NIX_CFLAGS_COMPILE_BEFORE_@suffixSalt@"
+    NIX_CFLAGS_COMPILE_BEFORE_@suffixSalt@="-m@darwinPlatformForCC@-version-min=${@darwinMinVersionVariable@_@suffixSalt@:-@darwinMinVersion@} $NIX_CFLAGS_COMPILE_BEFORE_@suffixSalt@"
 fi
 
 # That way forked processes will not extend these environment variables again.

pkgs/build-support/cc-wrapper/default.nix

@@ -109,6 +109,9 @@ let
   darwinMinVersion = optionalString stdenv.targetPlatform.isDarwin (
     stdenv.targetPlatform.darwinMinVersion
   );
+
+  darwinMinVersionVariable = optionalString stdenv.targetPlatform.isDarwin
+    stdenv.targetPlatform.darwinMinVersionVariable;
 in
 
 # Ensure bintools matches
@@ -131,7 +134,7 @@ stdenv.mkDerivation {
   gnugrep_bin = if nativeTools then "" else gnugrep;
 
   inherit targetPrefix suffixSalt;
-  inherit darwinPlatformForCC darwinMinVersion;
+  inherit darwinPlatformForCC darwinMinVersion darwinMinVersionVariable;
 
   outputs = [ "out" ] ++ optionals propagateDoc [ "man" "info" ];