Merge PR #27536

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

@@ -12,6 +12,7 @@
 , isGNU ? false, isClang ? cc.isClang or false, gnugrep ? null
 , buildPackages ? {}, hostPlatform, targetPlatform
 , runCommand ? null
+, useMacosReexportHack ? false
 }:
 
 with stdenv.lib;
@@ -278,7 +279,15 @@ stdenv.mkDerivation {
         ln -s $ldPath/${prefix}as $out/bin/${prefix}as
       fi
 
-      wrap ${prefix}ld ${preWrap ./ld-wrapper.sh} ''${ld:-$ldPath/${prefix}ld}
+    '' + (if !useMacosReexportHack then ''
+      wrap ${prefix}ld ${./ld-wrapper.sh} ''${ld:-$ldPath/${prefix}ld}
+    '' else ''
+      export binPrefix=${prefix}
+      ldInner="${prefix}ld-reexport-delegate"
+      wrap "$ldInner" ${./macos-sierra-reexport-hack.bash} ''${ld:-$ldPath/${prefix}ld}
+      wrap "${prefix}ld" ${./ld-wrapper.sh} "$out/bin/$ldInner"
+      unset ldInner
+    '') + ''
 
       if [ -e ${binutils_bin}/bin/${prefix}ld.gold ]; then
         wrap ${prefix}ld.gold ${preWrap ./ld-wrapper.sh} ${binutils_bin}/bin/${prefix}ld.gold
@@ -386,5 +395,7 @@ stdenv.mkDerivation {
     { description =
         stdenv.lib.attrByPath ["meta" "description"] "System C compiler" cc_
         + " (wrapper script)";
-    };
+  } // optionalAttrs useMacosReexportHack {
+    platforms = stdenv.lib.platforms.darwin;
+  };
 }

pkgs/build-support/cc-wrapper/macos-sierra-reexport-hack.bash

@@ -0,0 +1,106 @@
+#! @shell@
+
+set -eu -o pipefail
+
+path_backup="$PATH"
+if [ -n "@coreutils_bin@" ]; then
+  PATH="@coreutils_bin@/bin"
+fi
+
+declare -r recurThreshold=300
+
+declare overflowCount=0
+for ((n=0; n < $#; ++n)); do
+    case "${!n}" in
+        -l*) let overflowCount+=1 ;;
+        -reexport-l*) let overflowCount+=1 ;;
+        *) ;;
+    esac
+done
+
+declare -a allArgs=()
+
+if (( "$overflowCount" <= "$recurThreshold" )); then
+    allArgs=("$@")
+else
+    declare -a childrenLookup=() childrenLink=()
+
+    while (( $# )); do
+        case "$1" in
+            -L/*)
+                childrenLookup+=("$1")
+                allArgs+=("$1")
+                ;;
+            -L)
+                echo "cctools LD does not support '-L foo' or '-l foo'" >&2
+                exit 1
+                ;;
+            -l)
+                echo "cctools LD does not support '-L foo' or '-l foo'" >&2
+                exit 1
+                ;;
+            -lazy_library | -lazy_framework | -lto_library)
+                # We aren't linking any "azy_library", "to_library", etc.
+                allArgs+=("$1")
+                ;;
+            -lazy-l | -weak-l)    allArgs+=("$1") ;;
+                # We can't so easily prevent header issues from these.
+            -lSystem)             allArgs+=("$1") ;;
+                # Special case as indirection seems like a bad idea for something
+                # so fundamental. Can be removed for simplicity.
+            -l?* | -reexport-l?*) childrenLink+=("$1") ;;
+            *)                    allArgs+=("$1") ;;
+        esac
+
+        shift
+    done
+
+    declare n=0
+    while (( $n < "${#childrenLink[@]}" )); do
+        if [[ "${childrenLink[n]}" = -l* ]]; then
+            childrenLink[n]="-reexport${childrenLink[n]}"
+        fi
+        let ++n
+    done
+    unset n
+
+    declare -r outputNameLibless=$(basename $( \
+        if [[ -z "${outputName:+isUndefined}" ]]; then
+            echo unnamed
+        elif [[ "${outputName:0:3}" = lib ]]; then
+            echo "${outputName:3}"
+        else
+            echo "${outputName}"
+        fi))
+    declare -ra children=("$outputNameLibless-reexport-delegate-0" \
+                          "$outputNameLibless-reexport-delegate-1")
+
+    mkdir -p "$out/lib"
+
+    PATH="$PATH:@out@/bin"
+
+    symbolBloatObject=$outputNameLibless-symbol-hack.o
+    if [[ ! -e $symbolBloatObject ]]; then
+        printf '.private_extern _______child_hack_foo\nchild_hack_foo:\n' \
+            | @binPrefix@as -- -o $symbolBloatObject
+    fi
+
+    # first half of libs
+    @binPrefix@ld -macosx_version_min $MACOSX_DEPLOYMENT_TARGET -arch x86_64 -dylib \
+      -o "$out/lib/lib${children[0]}.dylib" \
+      -install_name "$out/lib/lib${children[0]}.dylib" \
+      "${childrenLookup[@]}" "$symbolBloatObject" \
+      "${childrenLink[@]:0:$((${#childrenLink[@]} / 2 ))}"
+
+    # second half of libs
+    @binPrefix@ld -macosx_version_min $MACOSX_DEPLOYMENT_TARGET -arch x86_64 -dylib \
+      -o "$out/lib/lib${children[1]}.dylib" \
+      -install_name "$out/lib/lib${children[1]}.dylib" \
+      "${childrenLookup[@]}" "$symbolBloatObject" \
+      "${childrenLink[@]:$((${#childrenLink[@]} / 2 ))}"
+
+    allArgs+=("-L$out/lib" "-l${children[0]}" "-l${children[1]}")
+fi
+
+PATH="$path_backup"
+exec @prog@ "${allArgs[@]}"