cc-wrapper: Add clang specific options to clang specific file

This way gcc doesn't need to be rebuilt because of clang. This also avoids
rebuilding clang when only the wrapper needs to be tweaked.

pkgs/build-support/cc-wrapper/add-clang-cc-cflags-before.sh

@@ -0,0 +1,11 @@
+needsTarget=true
+
+for p in "${params[@]}"; do
+    case "$p" in
+    -target | --target=*) needsTarget=false ;;
+    esac
+done
+
+if $needsTarget; then
+    extraBefore+=(-target @defaultTarget@)
+fi

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

@@ -29,7 +29,6 @@ cc1=0
 cxxInclude=1
 cxxLibrary=1
 cInclude=1
-needsTarget=@needsTarget@
 
 expandResponseParams "$@"
 linkType=$(checkLinkType "${params[@]}")
@@ -47,7 +46,6 @@ while (( "$n" < "$nParams" )); do
         -nostdinc) cInclude=0 cxxInclude=0 ;;
         -nostdinc++) cxxInclude=0 ;;
         -nostdlib) cxxLibrary=0 ;;
-        -target|--target=*) needsTarget=0;;
         -x)
             case "$p2" in
                 *-header) dontLink=1 ;;
@@ -161,8 +159,8 @@ if [ "$dontLink" != 1 ]; then
     export NIX_LINK_TYPE_@suffixSalt@=$linkType
 fi
 
-if [ $needsTarget == 1 ]; then
-    extraAfter+=(-target @defaultTarget@)
+if [[ -e @out@/nix-support/add-local-cc-cflags-before.sh ]]; then
+    source @out@/nix-support/add-local-cflags-before.sh
 fi
 
 # As a very special hack, if the arguments are just `-v', then don't

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

@@ -208,7 +208,6 @@ stdenv.mkDerivation {
     + ''
       export named_cc=${targetPrefix}cc
       export named_cxx=${targetPrefix}c++
-      export needsTarget=0
 
       if [ -e $ccPath/${targetPrefix}gcc ]; then
         wrap ${targetPrefix}gcc $wrapper $ccPath/${targetPrefix}gcc
@@ -216,8 +215,6 @@ stdenv.mkDerivation {
         export named_cc=${targetPrefix}gcc
         export named_cxx=${targetPrefix}g++
       elif [ -e $ccPath/clang ]; then
-        needsTarget=1
-        export defaultTarget=${targetPlatform.config}
         wrap ${targetPrefix}clang $wrapper $ccPath/clang
         ln -s ${targetPrefix}clang $out/bin/${targetPrefix}cc
         export named_cc=${targetPrefix}clang
@@ -228,8 +225,6 @@ stdenv.mkDerivation {
         wrap ${targetPrefix}g++ $wrapper $ccPath/${targetPrefix}g++
         ln -s ${targetPrefix}g++ $out/bin/${targetPrefix}c++
       elif [ -e $ccPath/clang++ ]; then
-        needsTarget=1
-        export defaultTarget=${targetPlatform.config}
         wrap ${targetPrefix}clang++ $wrapper $ccPath/clang++
         ln -s ${targetPrefix}clang++ $out/bin/${targetPrefix}c++
       fi
@@ -519,6 +514,15 @@ stdenv.mkDerivation {
       substituteAll ${../wrapper-common/utils.bash} $out/nix-support/utils.bash
     ''
 
+    ##
+    ## General Clang support
+    ## Needs to go after ^ because the for loop eats \n and makes this file an invalid script
+    ##
+    + optionalString isClang ''
+      export defaultTarget=${targetPlatform.config}
+      substituteAll ${./add-clang-cc-cflags-before.sh} $out/nix-support/add-local-cc-cflags-before.sh
+    ''
+
     ##
     ## Extra custom steps
     ##