merger: error when multiple rules have the same name (bazel-contrib#855)

Fixes bazel-contrib#850

merger/merger_test.go

@@ -935,14 +935,6 @@ func TestMatch(t *testing.T) {
 			gen:       `go_library(name = "lib")`,
 			old:       `cc_library(name = "lib")`,
 			wantError: true,
-		}, {
-			desc: "multiple_name_match",
-			gen:  `go_library(name = "lib")`,
-			old: `
-go_library(name = "lib")
-go_library(name = "lib")
-`,
-			wantError: true,
 		}, {
 			desc:      "attr_match",
 			gen:       `go_library(name = "x", importpath = "foo")`,

rule/rule.go

@@ -145,6 +145,9 @@ func LoadData(path, pkg string, data []byte) (*File, error) {
 		return nil, err
 	}
 	f := ScanAST(pkg, ast)
+	if err := checkFile(f); err != nil {
+		return nil, err
+	}
 	f.Content = data
 	return f, nil
 }
@@ -157,6 +160,9 @@ func LoadWorkspaceData(path, pkg string, data []byte) (*File, error) {
 		return nil, err
 	}
 	f := ScanAST(pkg, ast)
+	if err := checkFile(f); err != nil {
+		return nil, err
+	}
 	f.Content = data
 	return f, nil
 }
@@ -172,6 +178,9 @@ func LoadMacroData(path, pkg, defName string, data []byte) (*File, error) {
 		return nil, err
 	}
 	f := ScanASTBody(pkg, defName, ast)
+	if err := checkFile(f); err != nil {
+		return nil, err
+	}
 	f.Content = data
 	return f, nil
 }
@@ -903,3 +912,18 @@ func (s byAttrName) Less(i, j int) bool {
 func (s byAttrName) Swap(i, j int) {
 	s[i], s[j] = s[j], s[i]
 }
+
+func checkFile(f *File) error {
+	names := make(map[string]bool)
+	for _, r := range f.Rules {
+		name := r.Name()
+		if name == "" {
+			continue
+		}
+		if names[name] {
+			return fmt.Errorf("%s: multiple rules have the name %q", f.Path, name)
+		}
+		names[name] = true
+	}
+	return nil
+}

rule/rule_test.go

@@ -413,3 +413,23 @@ def repos():
 		}
 	}
 }
+
+func TestCheckFile(t *testing.T) {
+	f := File{Rules: []*Rule{
+		NewRule("go_repository", "com_google_cloud_go_pubsub"),
+		NewRule("go_repository", "com_google_cloud_go_pubsub"),
+	}}
+	err := checkFile(&f)
+	if err == nil {
+		t.Errorf("muliple rules with the same name should not be tolerated")
+	}
+
+	f = File{Rules: []*Rule {
+		NewRule("go_rules_dependencies", ""),
+		NewRule("go_register_toolchains", ""),
+	}}
+	err = checkFile(&f)
+	if err != nil {
+		t.Errorf("unexpected error: %v", err)
+	}
+}