buildRustCrate: add support for cargo::rustc-cdylib-link-arg

pkgs/build-support/rust/build-rust-crate/configure-crate.nix

@@ -14,6 +14,7 @@
 , crateLicenseFile
 , crateLinks
 , crateName
+, crateType
 , crateReadme
 , crateRenames
 , crateRepository
@@ -209,6 +210,11 @@ in ''
      EXTRA_LINK_LIBS=$(sed -n "s/^cargo::\{0,1\}rustc-link-lib=\(.*\)/\1/p" target/build/${crateName}.opt | tr '\n' ' ')
      EXTRA_LINK_SEARCH=$(sed -n "s/^cargo::\{0,1\}rustc-link-search=\(.*\)/\1/p" target/build/${crateName}.opt | tr '\n' ' ' | sort -u)
 
+     ${lib.optionalString (lib.elem "cdylib" crateType) ''
+     CRATE_TYPE_IS_CDYLIB="true"
+     EXTRA_CDYLIB_LINK_ARGS=$(sed -n "s/^cargo::\{0,1\}rustc-cdylib-link-arg=\(.*\)/-C link-arg=\1/p" target/build/${crateName}.opt | tr '\n' ' ')
+''}
+
      # We want to read part of every line that has cargo:rustc-env= prefix and
      # export it as environment variables. This turns out tricky if the lines
      # have spaces: we can't wrap the command in double quotes as that captures

pkgs/build-support/rust/build-rust-crate/default.nix

@@ -345,7 +345,7 @@ crate_: lib.makeOverridable
 
 
       configurePhase = configureCrate {
-        inherit crateName buildDependencies completeDeps completeBuildDeps crateDescription
+        inherit crateName crateType buildDependencies completeDeps completeBuildDeps crateDescription
           crateFeatures crateRenames libName build workspace_member release libPath crateVersion crateLinks
           extraLinkFlags extraRustcOptsForBuildRs
           crateLicense crateLicenseFile crateReadme crateRepository crateRustVersion

pkgs/build-support/rust/build-rust-crate/lib.sh

@@ -114,6 +114,12 @@ setup_link_paths() {
      tr '\n' ' ' < target/link > target/link_
      LINK=$(cat target/link_)
   fi
+
+  # Add "rustc-cdylib-link-arg" as linker arguments
+  # https://doc.rust-lang.org/cargo/reference/build-scripts.html#rustc-cdylib-link-arg
+  if [[ -n "$CRATE_TYPE_IS_CDYLIB" ]]; then
+    EXTRA_BUILD+=" $EXTRA_CDYLIB_LINK_ARGS"
+  fi
 }
 
 search_for_bin_path() {