cargoDoc: add a fallback search for non-cross-compiled docs (#708)

CHANGELOG.md

@@ -20,6 +20,12 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 * `downloadCargoPackageFromGit` will now set `fetchLFS = true` when fetching git
   repos with defined output hashes
 
+### Fixed
+* `cargoDoc` correctly honors `docInstallRoot` when specified
+* `cargoDoc` falls back to installing from `./target/doc` even if
+  `$CARGO_BUILD_TARGET` is set but `./target/$CARGO_BUILD_TARGET/doc` does not
+  exist
+
 ### Removed
 * The deprecated top-level (flake) attribute `lib` no longer exists. Please use
   `mkLib` with an instance of `pkgs` instead.
@@ -68,7 +74,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 ## [0.17.2] - 2024-05-26
 
 ### Fixed
-* `removeReferencesToVendoredSources` has been optimzed to search for source
+* `removeReferencesToVendoredSources` has been optimized to search for source
   references only once. For derivations which install many files, this phase can
   run up to 99% faster than before.
 * `cleanCargoToml` now cleans underscored versions of the same attributes (e.g.

docs/API.md

@@ -495,6 +495,8 @@ Except where noted below, all derivation attributes are delegated to
   `$CARGO_TARGET_DIR` (or default to `./target` if not set) and
   `$CARGO_BUILD_TARGET` (if set).
   - Default value: `"${CARGO_TARGET_DIR:-target}/${CARGO_BUILD_TARGET:-}/doc"`
+    if such a directory exists, otherwise falls back to
+    `"${CARGO_TARGET_DIR:-target}/doc"`
 
 #### Remove attributes
 The following attributes will be removed before being lowered to
@@ -503,7 +505,6 @@ environment variables during the build, you can bring them back via
 `.overrideAttrs`.
 * `cargoDocExtraArgs`
 * `cargoExtraArgs`
-* `docInstallRoot`
 
 ### `craneLib.cargoFmt`
 

lib/cargoDoc.nix

@@ -9,7 +9,6 @@ let
   args = (builtins.removeAttrs origArgs [
     "cargoDocExtraArgs"
     "cargoExtraArgs"
-    "docInstallRoot"
   ]);
 in
 mkCargoDerivation (args // {
@@ -22,10 +21,17 @@ mkCargoDerivation (args // {
   docInstallRoot = args.docInstallRoot or "";
 
   # NB: cargo always places docs at the root of the target directory
-  # even when building in release mode, except when cross-compiling targets
+  # even when building in release mode, except when cross-compiling targets.
+  # However, even if CARGO_BUILD_TARGET is set but does not result in cross-compilation
+  # cargo will still put the docs in the root of the target directory, so we need to take
+  # that into account
   installPhaseCommand = ''
     if [ -z "''${docInstallRoot:-}" ]; then
       docInstallRoot="''${CARGO_TARGET_DIR:-target}/''${CARGO_BUILD_TARGET:-}/doc"
+
+      if ! [ -d "''${docInstallRoot}" ]; then
+        docInstallRoot="''${CARGO_TARGET_DIR:-target}/doc"
+      fi
     fi
 
     mkdir -p $out/share