crateNameFromCargoToml: warn when values can't be found (#237)

CHANGELOG.md

@@ -6,6 +6,12 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ## Unreleased
 
+### Changed
+* A warning will now be emitted if a derivation's `pname` or `version`
+  attributes are not set and the value cannot be loaded from the derivation's
+  root `Cargo.toml`. To resolve it consider setting `pname = "...";` or `version
+  = "...";` explicitly on the derivation.
+
 ## [0.11.2] - 2023-02-11
 
 ### Fixed

checks/default.nix

@@ -380,11 +380,13 @@ in
   workspace = myLib.buildPackage {
     src = myLib.cleanCargoSource ./workspace;
     pname = "workspace";
+    version = "0.0.1";
   };
 
   workspaceHack = myLib.buildPackage {
     src = myLib.cleanCargoSource ./workspace-hack;
     pname = "workspace-hack";
+    version = "0.0.1";
   };
 
   workspaceInheritance = myLib.buildPackage {
@@ -394,6 +396,8 @@ in
 
   # https://github.com/ipetkov/crane/issues/209
   workspaceRootNotAtSourceRoot = myLib.buildPackage {
+    pname = "workspaceRootNotAtSourceRoot";
+    version = "0.0.1";
     src = myLib.cleanCargoSource ./workspace-not-at-root;
     postUnpack = ''
       cd $sourceRoot/workspace
@@ -411,6 +415,7 @@ in
   workspaceGit = myLib.buildPackage {
     src = myLib.cleanCargoSource ./workspace-git;
     pname = "workspace-git";
+    version = "0.0.1";
   };
 })
 )

docs/API.md

@@ -605,8 +605,10 @@ raised during evaluation.
 Extract a crate's name and version from its Cargo.toml file.
 
 The resulting `pname` attribute will be populated with the value of the
-Cargo.toml's `package.name` attribute, if present. Otherwise a placeholder value
-will be used.
+Cargo.toml's (top-level) `package.name` attribute, if present and if the
+value is a string. Otherwise `workspace.package.name` will be used if it is
+present _and_ the value is a string. Otherwise a placeholder version field will
+be used.
 
 The resulting `version` attribute will be populated with the value of the
 Cargo.toml's (top-level) `package.version` attribute, if present and if the

lib/crateNameFromCargoToml.nix

@@ -20,9 +20,31 @@ let
   );
 
   toml = builtins.fromTOML cargoTomlContents;
+
+  debugPath =
+    if args ? cargoTomlContents
+    then "provided Cargo.toml contents"
+    else cargoToml;
+
+  traceMsg = tomlName: drvName: placeholder: lib.trivial.warn
+    "crane cannot find ${tomlName} attribute in ${debugPath}, consider setting `${drvName} = \"...\";` explicitly"
+    placeholder;
 in
 {
-  pname = toml.package.name or "cargo-package";
+  # Now that cargo supports workspace inheritance we attempt to select a name
+  # with the following priorities:
+  # - choose `[package.name]` if the value is present and a string
+  #   (i.e. it isn't `[package.name] = { workspace = "true" }`)
+  # - choose `[workspace.package.name]` if it is present (and a string for good measure)
+  # - otherwise, fall back to a placeholder
+  pname =
+    let
+      packageName = toml.package.name or null;
+      workspacePackageName = toml.workspace.package.name or null;
+    in
+    if lib.isString packageName then packageName
+    else if lib.isString workspacePackageName then workspacePackageName
+    else traceMsg "name" "pname" "cargo-package";
 
   # Now that cargo supports workspace inheritance we attempt to select a version
   # string with the following priorities:
@@ -37,5 +59,5 @@ in
     in
     if lib.isString packageVersion then packageVersion
     else if lib.isString workspacePackageVersion then workspacePackageVersion
-    else "0.0.1";
+    else traceMsg "version" "version" "0.0.1";
 }

lib/mkCargoDerivation.nix

@@ -5,6 +5,7 @@
 , crateNameFromCargoToml
 , inheritCargoArtifactsHook
 , installCargoArtifactsHook
+, lib
 , stdenv
 , vendorCargoDeps
 , zstd