Add a directive for cargo lint extraction

Author: mrkkrp

generation_tests/cargo/extract_cargo_lints/BUILD.in

@@ -0,0 +1,2 @@
+# gazelle:rust_mode generate_from_cargo
+# gazelle:rust_extract_cargo_lints true

generation_tests/cargo/extract_cargo_lints/BUILD.out

@@ -0,0 +1,38 @@
+load("@rules_rust//cargo:defs.bzl", "extract_cargo_lints")
+load("@rules_rust//rust:defs.bzl", "rust_binary", "rust_library", "rust_test")
+
+# gazelle:rust_mode generate_from_cargo
+# gazelle:rust_extract_cargo_lints true
+
+extract_cargo_lints(
+    name = "workspace_lints",
+    manifest = "Cargo.toml",
+    workspace = "//:Cargo.toml",
+)
+
+rust_library(
+    name = "extract_lints_test_lib",
+    srcs = ["src/lib.rs"],
+    compile_data = ["Cargo.toml"],
+    crate_name = "extract_lints_test",
+    edition = "2021",
+    lint_config = ":workspace_lints",
+    visibility = ["//visibility:public"],
+)
+
+rust_binary(
+    name = "extract_lints_test",
+    srcs = ["src/main.rs"],
+    compile_data = ["Cargo.toml"],
+    edition = "2021",
+    lint_config = ":workspace_lints",
+    visibility = ["//visibility:public"],
+)
+
+rust_test(
+    name = "extract_lints_test_lib_test",
+    compile_data = ["Cargo.toml"],
+    crate = ":extract_lints_test_lib",
+    edition = "2021",
+    lint_config = ":workspace_lints",
+)

generation_tests/cargo/extract_cargo_lints/Cargo.toml

@@ -0,0 +1,4 @@
+[package]
+name = "extract_lints_test"
+version = "0.1.0"
+edition = "2021"

generation_tests/cargo/extract_cargo_lints/README.md

@@ -0,0 +1,2 @@
+
+Tests that the rust_extract_cargo_lints directive generates extract_cargo_lints targets and adds lint_config attributes.

generation_tests/cargo/extract_cargo_lints/WORKSPACE

@@ -0,0 +1,13 @@
+pub fn add(a: i32, b: i32) -> i32 {
+    a + b
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_add() {
+        assert_eq!(add(1, 2), 3);
+    }
+}

generation_tests/cargo/extract_cargo_lints/src/lib.rs

@@ -0,0 +1,3 @@
+fn main() {
+    println!("Hello, world!");
+}

generation_tests/cargo/extract_cargo_lints/src/main.rs

@@ -401,6 +401,30 @@ func (l *rustLang) generateRulesFromCargo(args language.GenerateArgs) language.G
 				// Determine if there are binaries (which would have main.rs files)
 				hasMainRs := len(response.Binaries) > 0
 
+				// Check if we're generating any Rust targets that use lint_config
+				// Note: cargo_build_script does not use lint_config, so we exclude it
+				hasAnyRustTargets := response.Library != nil ||
+					len(response.Binaries) > 0 ||
+					len(response.Tests) > 0 ||
+					len(response.Benches) > 0 ||
+					len(response.Examples) > 0
+
+				// Generate extract_cargo_lints target only if we're generating Rust targets that use it
+				if cfg.ExtractCargoLints && hasAnyRustTargets {
+					lintsRule := rule.NewRule("extract_cargo_lints", "workspace_lints")
+					lintsRule.SetAttr("manifest", "Cargo.toml")
+					lintsRule.SetAttr("workspace", "//:Cargo.toml")
+					result.Gen = append(result.Gen, lintsRule)
+					result.Imports = append(result.Imports, RuleData{
+						rule:            lintsRule,
+						responses:       []*pb.RustImportsResponse{},
+						testedCrate:     nil,
+						buildScript:     nil,
+						parentCrateName: parentCrateName,
+						aliases:         dependencyAliases,
+					})
+				}
+
 				if response.Library != nil {
 					// if there is a main.rs next to lib.rs, they will both have the same crate
 					// name; need to give the library a different name
@@ -472,6 +496,10 @@ func (l *rustLang) generateRulesFromCargo(args language.GenerateArgs) language.G
 					testRule.SetAttr("edition", parentCrateEdition)
 				}
 
+				if cfg.ExtractCargoLints {
+					testRule.SetAttr("lint_config", ":workspace_lints")
+				}
+
 				result.Gen = append(result.Gen, testRule)
 				result.Imports = append(result.Imports, RuleData{
 					rule:            testRule,
@@ -581,6 +609,10 @@ func (l *rustLang) generateCargoRule(c *config.Config, args *language.GenerateAr
 		newRule.SetAttr("crate_features", enabledFeatures)
 	}
 
+	if cfg.ExtractCargoLints {
+		newRule.SetAttr("lint_config", ":workspace_lints")
+	}
+
 	var buildScript *label.Label = nil
 	if hasBuildScript && (kind == "rust_library" || kind == "rust_binary") {
 		build_script_label, err := label.Parse(":build_script")

rust_language/generate.go

@@ -65,6 +65,11 @@ var (
 	// Ignore a specific import when resolving dependencies.
 	// usage: # gazelle:rust_ignore_import <import name>
 	ignoreImportDirective string = "rust_ignore_import"
+
+	// Extract cargo lints from Cargo.toml files.
+	// When enabled in generate_from_cargo mode, creates extract_cargo_lints targets
+	// and adds lint_config attributes to all generated targets.
+	extractCargoLintsDirective string = "rust_extract_cargo_lints"
 )
 
 type rustConfig struct {
@@ -78,6 +83,7 @@ type rustConfig struct {
 	DefaultEdition     string
 	SrcsGlob           bool
 	IgnoredImports     map[string]bool
+	ExtractCargoLints  bool
 }
 
 func (cfg *rustConfig) Clone() *rustConfig {
@@ -121,9 +127,10 @@ func (*rustLang) Name() string { return langName }
 var (
 	commonDefs []string = []string{"rust_library", "rust_binary", "rust_test",
 		"rust_proc_macro", "rust_shared_library", "rust_static_library"}
-	protoDefs []string = []string{"rust_proto_library", "rust_grpc_library"}
-	prostDefs []string = []string{"rust_prost_library"}
-	cargoDefs []string = []string{"cargo_build_script"}
+	protoDefs      []string = []string{"rust_proto_library", "rust_grpc_library"}
+	prostDefs      []string = []string{"rust_prost_library"}
+	cargoDefs      []string = []string{"cargo_build_script"}
+	cargoLintsDefs []string = []string{"extract_cargo_lints"}
 )
 
 var resolvableDefs = append(
@@ -164,6 +171,13 @@ func (*rustLang) Kinds() map[string]rule.KindInfo {
 		}
 	}
 
+	for _, cargoLintsDef := range cargoLintsDefs {
+		kinds[cargoLintsDef] = rule.KindInfo{
+			MergeableAttrs: map[string]bool{},
+			ResolveAttrs:   map[string]bool{},
+		}
+	}
+
 	return kinds
 }
 
@@ -183,7 +197,7 @@ func (*rustLang) Loads() []rule.LoadInfo {
 		},
 		{
 			Name:    "@rules_rust//cargo:defs.bzl",
-			Symbols: cargoDefs,
+			Symbols: append(cargoDefs, cargoLintsDefs...),
 		},
 	}
 }
@@ -201,7 +215,7 @@ func (*rustLang) KnownDirectives() []string {
 	return []string{modeDirective, lockfileDirective, cargoLockfileDirective,
 		cratesPrefixDirective, procMacroOverrideDirective, allowUnusedCrateDirective,
 		rustFeatureDirective, defaultFeaturesDirective, defaultEditionDirective,
-		srcsGlobDirective, ignoreImportDirective}
+		srcsGlobDirective, ignoreImportDirective, extractCargoLintsDirective}
 }
 
 func (l *rustLang) GetConfig(c *config.Config) *rustConfig {
@@ -238,6 +252,7 @@ func (l *rustLang) Configure(c *config.Config, rel string, from *rule.File) {
 			DefaultEdition:     "",
 			SrcsGlob:           false,
 			IgnoredImports:     make(map[string]bool),
+			ExtractCargoLints:  false,
 		}
 	} else {
 		// NOTE(will): important to clone so that we don't leak state across directories
@@ -306,6 +321,13 @@ func (l *rustLang) Configure(c *config.Config, rel string, from *rule.File) {
 				cfg.SrcsGlob = value
 			} else if directive.Key == ignoreImportDirective {
 				cfg.IgnoredImports[directive.Value] = true
+			} else if directive.Key == extractCargoLintsDirective {
+				value, err := strconv.ParseBool(directive.Value)
+				if err != nil {
+					l.Log(c, logFatal, "bad %s, should be gazelle:%s <true|false>",
+						directive.Key, directive.Key)
+				}
+				cfg.ExtractCargoLints = value
 			}
 		}
 	}