cc-wrapper: adding a cc-wrapper-hook to the cc-wrapper

doc/stdenv/stdenv.chapter.md

@@ -1140,6 +1140,13 @@ Here are some more packages that provide a setup hook. Since the list of hooks i
 Many other packages provide hooks, that are not part of `stdenv`. You can find
 these in the [Hooks Reference](#chap-hooks).
 
+### Compiler and Linker wrapper hooks {#compiler-linker-wrapper-hooks}
+
+If the file `${cc}/nix-support/cc-wrapper-hook` exists, it will be run at the end of the [compiler wrapper](#cc-wrapper).
+If the file `${binutils}/nix-support/post-link-hook` exists, it will be run at the end of the linker wrapper.
+These hooks allow a user to inject code into the wrappers.
+As an example, these hooks can be used to extract `extraBefore`, `params` and `extraAfter` which store all the command line arguments passed to the compiler and linker respectively.
+
 ## Purity in Nixpkgs {#sec-purity-in-nixpkgs}
 
 *Measures taken to prevent dependencies on packages outside the store, and what you can do to prevent them.*

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

@@ -219,6 +219,12 @@ fi
 PATH="$path_backup"
 # Old bash workaround, see above.
 
+# if a cc-wrapper-hook exists, run it.
+if [[ -e @out@/nix-support/cc-wrapper-hook ]]; then
+    compiler=@prog@
+    source @out@/nix-support/cc-wrapper-hook
+fi
+
 if (( "${NIX_CC_USE_RESPONSE_FILE:-@use_response_file_by_default@}" >= 1 )); then
     exec @prog@ @<(printf "%q\n" \
        ${extraBefore+"${extraBefore[@]}"} \