buildRustCrate: pass extraRustcOpts to configure crate

Previously build flags would not be available during the configure phase
while they might be required to build the `build.rs` file.

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

@@ -8,11 +8,11 @@
   let
 
     deps = makeDeps dependencies;
-        rustcOpts =
-          lib.lists.foldl' (opts: opt: opts + " " + opt)
-            (if release then "-C opt-level=3" else "-C debuginfo=2")
-            (["-C codegen-units=1"] ++ extraRustcOpts);
-        rustcMeta = "-C metadata=${metadata} -C extra-filename=-${metadata}";
+    rustcOpts =
+      lib.lists.foldl' (opts: opt: opts + " " + opt)
+        (if release then "-C opt-level=3" else "-C debuginfo=2")
+        (["-C codegen-units=1"] ++ extraRustcOpts);
+    rustcMeta = "-C metadata=${metadata} -C extra-filename=-${metadata}";
 
     # Some platforms have different names for rustc.
     rustPlatform =

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

@@ -1,9 +1,27 @@
 { lib, stdenv, echo_build_heading, noisily, makeDeps }:
-{ build, buildDependencies, colors, completeBuildDeps, completeDeps, crateAuthors, crateFeatures, crateName, crateVersion, extraLinkFlags, libName, libPath, release, target_os, verbose, workspace_member }:
+{ build
+, buildDependencies
+, colors
+, completeBuildDeps
+, completeDeps
+, crateAuthors
+, crateFeatures
+, crateName
+, crateVersion
+, extraLinkFlags
+, extraRustcOpts
+, libName
+, libPath
+, release
+, target_os
+, verbose
+, workspace_member }:
 let version_ = lib.splitString "-" crateVersion;
     versionPre = if lib.tail version_ == [] then "" else builtins.elemAt version_ 1;
     version = lib.splitString "." (lib.head version_);
-    rustcOpts = (if release then "-C opt-level=3" else "-C debuginfo=2");
+    rustcOpts = lib.lists.foldl' (opts: opt: opts + " " + opt)
+        (if release then "-C opt-level=3" else "-C debuginfo=2")
+        (["-C codegen-units=1"] ++ extraRustcOpts);
     buildDeps = makeDeps buildDependencies;
     authors = lib.concatStringsSep ":" crateAuthors;
     optLevel = if release then 3 else 0;

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

@@ -136,13 +136,13 @@ stdenv.mkDerivation (rec {
         (crate.type or ["lib"]);
     colors = lib.attrByPath [ "colors" ] "always" crate;
     extraLinkFlags = builtins.concatStringsSep " " (crate.extraLinkFlags or []);
+    extraRustcOpts = (if crate ? extraRustcOpts then crate.extraRustcOpts else []) ++ extraRustcOpts_;
     configurePhase = configureCrate {
       inherit crateName buildDependencies completeDeps completeBuildDeps
               crateFeatures libName build workspace_member release libPath crateVersion
-              extraLinkFlags
+              extraLinkFlags extraRustcOpts
               crateAuthors verbose colors target_os;
     };
-    extraRustcOpts = (if crate ? extraRustcOpts then crate.extraRustcOpts else []) ++ extraRustcOpts_;
     buildPhase = buildCrate {
       inherit crateName dependencies
               crateFeatures libName release libPath crateType