lib{std,}c++: Fix setup hooks for cross

pkgs/development/compilers/gcc/libstdc++-hook.sh

@@ -1,2 +1,13 @@
-export NIX_CXXSTDLIB_COMPILE+=" -isystem $(echo -n @gcc@/include/c++/*) -isystem $(echo -n @gcc@/include/c++/*)/$(@gcc@/bin/gcc -dumpmachine)"
+# The `hostOffset` describes how the host platform of the dependencies are slid
-export NIX_CXXSTDLIB_LINK=" -stdlib=libstdc++"
+# relative to the depending package. It is brought into scope of the setup hook
+# defined as the role of the dependency whose hooks is being run.
+case $hostOffset in
+    -1) local role='BUILD_' ;;
+    0)  local role='' ;;
+    1)  local role='TARGET_' ;;
+    *)  echo "cc-wrapper: Error: Cannot be used with $hostOffset-offset deps" >2;
+        return 1 ;;
+esac
+
+export NIX_${role}CXXSTDLIB_COMPILE+=" -isystem $(echo -n @gcc@/include/c++/*) -isystem $(echo -n @gcc@/include/c++/*)/$(@gcc@/bin/gcc -dumpmachine)"
+export NIX_${role}CXXSTDLIB_LINK=" -stdlib=libstdc++"

pkgs/development/compilers/llvm/3.5/libc++/setup-hook.sh

@@ -1,3 +1,14 @@
+# The `hostOffset` describes how the host platform of the dependencies are slid
+# relative to the depending package. It is brought into scope of the setup hook
+# defined as the role of the dependency whose hooks is being run.
+case $hostOffset in
+    -1) local role='BUILD_' ;;
+    0)  local role='' ;;
+    1)  local role='TARGET_' ;;
+    *)  echo "cc-wrapper: Error: Cannot be used with $hostOffset-offset deps" >2;
+        return 1 ;;
+esac
+
 linkCxxAbi="@linkCxxAbi@"
-export NIX_CXXSTDLIB_COMPILE+=" -isystem @out@/include/c++/v1"
+export NIX_${role}CXXSTDLIB_COMPILE+=" -isystem @out@/include/c++/v1"
-export NIX_CXXSTDLIB_LINK=" -stdlib=libc++${linkCxxAbi:+" -lc++abi"}"
+export NIX_${role}CXXSTDLIB_LINK=" -stdlib=libc++${linkCxxAbi:+" -lc++abi"}"

pkgs/development/compilers/llvm/3.7/libc++/setup-hook.sh

@@ -1,3 +1,14 @@
+# The `hostOffset` describes how the host platform of the dependencies are slid
+# relative to the depending package. It is brought into scope of the setup hook
+# defined as the role of the dependency whose hooks is being run.
+case $hostOffset in
+    -1) local role='BUILD_' ;;
+    0)  local role='' ;;
+    1)  local role='TARGET_' ;;
+    *)  echo "cc-wrapper: Error: Cannot be used with $hostOffset-offset deps" >2;
+        return 1 ;;
+esac
+
 linkCxxAbi="@linkCxxAbi@"
-export NIX_CXXSTDLIB_COMPILE+=" -isystem @out@/include/c++/v1"
+export NIX_${role}CXXSTDLIB_COMPILE+=" -isystem @out@/include/c++/v1"
-export NIX_CXXSTDLIB_LINK=" -stdlib=libc++${linkCxxAbi:+" -lc++abi"}"
+export NIX_${role}CXXSTDLIB_LINK=" -stdlib=libc++${linkCxxAbi:+" -lc++abi"}"

pkgs/development/compilers/llvm/3.8/libc++/setup-hook.sh

@@ -1,3 +1,14 @@
+# The `hostOffset` describes how the host platform of the dependencies
+# relative to the depending package. It is brought into scope of the setup hook
+# defined as the role of the dependency whose hooks is being run.
+case $hostOffset in
+    -1) local role='BUILD_' ;;
+    0)  local role='' ;;
+    1)  local role='TARGET_' ;;
+    *)  echo "cc-wrapper: Error: Cannot be used with $hostOffset-offset deps" >2;
+        return 1 ;;
+esac
+
 linkCxxAbi="@linkCxxAbi@"
-export NIX_CXXSTDLIB_COMPILE+=" -isystem @out@/include/c++/v1"
+export NIX_${role}CXXSTDLIB_COMPILE+=" -isystem @out@/include/c++/v1"
-export NIX_CXXSTDLIB_LINK=" -stdlib=libc++${linkCxxAbi:+" -lc++abi"}"
+export NIX_${role}CXXSTDLIB_LINK=" -stdlib=libc++${linkCxxAbi:+" -lc++abi"}"

pkgs/development/compilers/llvm/3.9/libc++/setup-hook.sh

@@ -1,3 +1,14 @@
+# The `hostOffset` describes how the host platform of the dependencies
+# relative to the depending package. It is brought into scope of the setup hook
+# defined as the role of the dependency whose hooks is being run.
+case $hostOffset in
+    -1) local role='BUILD_' ;;
+    0)  local role='' ;;
+    1)  local role='TARGET_' ;;
+    *)  echo "cc-wrapper: Error: Cannot be used with $hostOffset-offset deps" >2;
+        return 1 ;;
+esac
+
 linkCxxAbi="@linkCxxAbi@"
-export NIX_CXXSTDLIB_COMPILE+=" -isystem @out@/include/c++/v1"
+export NIX_${role}CXXSTDLIB_COMPILE+=" -isystem @out@/include/c++/v1"
-export NIX_CXXSTDLIB_LINK=" -stdlib=libc++${linkCxxAbi:+" -lc++abi"}"
+export NIX_${role}CXXSTDLIB_LINK=" -stdlib=libc++${linkCxxAbi:+" -lc++abi"}"

pkgs/development/compilers/llvm/4/libc++/setup-hook.sh

@@ -1,3 +1,14 @@
+# The `hostOffset` describes how the host platform of the dependencies
+# relative to the depending package. It is brought into scope of the setup hook
+# defined as the role of the dependency whose hooks is being run.
+case $hostOffset in
+    -1) local role='BUILD_' ;;
+    0)  local role='' ;;
+    1)  local role='TARGET_' ;;
+    *)  echo "cc-wrapper: Error: Cannot be used with $hostOffset-offset deps" >2;
+        return 1 ;;
+esac
+
 linkCxxAbi="@linkCxxAbi@"
-export NIX_CXXSTDLIB_COMPILE+=" -isystem @out@/include/c++/v1"
+export NIX_${role}CXXSTDLIB_COMPILE+=" -isystem @out@/include/c++/v1"
-export NIX_CXXSTDLIB_LINK=" -stdlib=libc++${linkCxxAbi:+" -lc++abi"}"
+export NIX_${role}CXXSTDLIB_LINK=" -stdlib=libc++${linkCxxAbi:+" -lc++abi"}"

pkgs/development/compilers/llvm/5/libc++/setup-hook.sh

@@ -1,3 +1,14 @@
+# The `hostOffset` describes how the host platform of the dependencies
+# relative to the depending package. It is brought into scope of the setup hook
+# defined as the role of the dependency whose hooks is being run.
+case $hostOffset in
+    -1) local role='BUILD_' ;;
+    0)  local role='' ;;
+    1)  local role='TARGET_' ;;
+    *)  echo "cc-wrapper: Error: Cannot be used with $hostOffset-offset deps" >2;
+        return 1 ;;
+esac
+
 linkCxxAbi="@linkCxxAbi@"
-export NIX_CXXSTDLIB_COMPILE+=" -isystem @out@/include/c++/v1"
+export NIX_${role}CXXSTDLIB_COMPILE+=" -isystem @out@/include/c++/v1"
-export NIX_CXXSTDLIB_LINK=" -stdlib=libc++${linkCxxAbi:+" -lc++abi"}"
+export NIX_${role}CXXSTDLIB_LINK=" -stdlib=libc++${linkCxxAbi:+" -lc++abi"}"

pkgs/development/compilers/llvm/6/libc++/setup-hook.sh

@@ -1,3 +1,14 @@
+# The `hostOffset` describes how the host platform of the dependencies
+# relative to the depending package. It is brought into scope of the setup hook
+# defined as the role of the dependency whose hooks is being run.
+case $hostOffset in
+    -1) local role='BUILD_' ;;
+    0)  local role='' ;;
+    1)  local role='TARGET_' ;;
+    *)  echo "cc-wrapper: Error: Cannot be used with $hostOffset-offset deps" >2;
+        return 1 ;;
+esac
+
 linkCxxAbi="@linkCxxAbi@"
-export NIX_CXXSTDLIB_COMPILE+=" -isystem @out@/include/c++/v1"
+export NIX_${role}CXXSTDLIB_COMPILE+=" -isystem @out@/include/c++/v1"
-export NIX_CXXSTDLIB_LINK=" -stdlib=libc++${linkCxxAbi:+" -lc++abi"}"
+export NIX_${role}CXXSTDLIB_LINK=" -stdlib=libc++${linkCxxAbi:+" -lc++abi"}"