fix: skip decorator factory when scanning for constructor parens

Address Gemini Code Assist review: when the member is a nameless
Constructor and it carries a decorator factory (e.g. @dec()), using
node.Pos() as the parameter-paren search origin matches the `(` of
the decorator factory first and produces an inverted range.

Anchor the scan at the first token after the decorators instead,
keeping the prior behaviour for named methods/getters/setters via the
name.End() override. Adds a utils-level regression test that asserts
the range spans just the `constructor` keyword.

Also sync the `require-yield` JS mirror test (and its snapshot) with
the Go expectations updated in the previous commit — the columns now
land after the decorators instead of on `@`.

Author: fansenze

internal/utils/function_head_loc_test.go

@@ -0,0 +1,65 @@
+package utils_test
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/microsoft/typescript-go/shim/ast"
+	"github.com/web-infra-dev/rslint/internal/plugins/typescript/rules/fixtures"
+	"github.com/web-infra-dev/rslint/internal/rule_tester"
+	"github.com/web-infra-dev/rslint/internal/utils"
+)
+
+// TestGetFunctionHeadLocConstructorWithDecoratorFactory pins down that the
+// reported range for a nameless member (constructor) whose class has a
+// decorator factory starts *after* the decorators and ends at the
+// parameter-list `(` — not at the decorator-factory `(`. Without skipping
+// the decorators when computing the parameter-search origin, the scan would
+// match the `(` inside `@Dec()` and produce an inverted range.
+func TestGetFunctionHeadLocConstructorWithDecoratorFactory(t *testing.T) {
+	code := "declare function Dec(): any;\nclass A {\n  @Dec()\n  constructor(x: number) {}\n}\n"
+
+	helper := rule_tester.NewProgramHelper(fixtures.GetRootDir())
+	_, sourceFile, err := helper.CreateTestProgram(code, "a.ts", "tsconfig.json")
+	if err != nil {
+		t.Fatalf("CreateTestProgram: %v", err)
+	}
+
+	var ctor *ast.Node
+	var walk func(n *ast.Node) bool
+	walk = func(n *ast.Node) bool {
+		if n == nil {
+			return false
+		}
+		if n.Kind == ast.KindConstructor {
+			ctor = n
+			return true
+		}
+		stop := false
+		n.ForEachChild(func(c *ast.Node) bool {
+			if walk(c) {
+				stop = true
+				return true
+			}
+			return false
+		})
+		return stop
+	}
+	walk(sourceFile.AsNode())
+
+	if ctor == nil {
+		t.Fatal("constructor not found in parsed source")
+	}
+
+	r := utils.GetFunctionHeadLoc(sourceFile, ctor)
+	if r.Pos() >= r.End() {
+		t.Fatalf("inverted range: pos=%d end=%d", r.Pos(), r.End())
+	}
+
+	got := sourceFile.Text()[r.Pos():r.End()]
+	// "constructor" is 11 characters, the head range must cover just the
+	// keyword up to (but not including) the parameter `(`.
+	if strings.TrimSpace(got) != "constructor" {
+		t.Fatalf("unexpected head range text: %q (pos=%d end=%d)", got, r.Pos(), r.End())
+	}
+}

internal/utils/ts_eslint.go

@@ -196,9 +196,10 @@ func GetFunctionHeadLoc(sourceFile *ast.SourceFile, node *ast.Node) core.TextRan
 	switch node.Kind {
 	case ast.KindMethodDeclaration, ast.KindGetAccessor, ast.KindSetAccessor, ast.KindConstructor:
 		start := nodeStartSkippingDecorators(sourceFile, node)
-		// Start scanning for the parameters `(` after the method name to avoid
-		// matching the `(` of a decorator factory call like `@dec()`.
-		searchFrom := node.Pos()
+		// Start scanning for the parameters `(` after any decorator factory
+		// (e.g. `@dec()`) and after the method name. Nameless constructors
+		// fall back to the first token after the decorators.
+		searchFrom := start.Pos()
 		if name := node.Name(); name != nil {
 			searchFrom = name.End()
 		}

packages/rslint-test-tools/tests/eslint/rules/__snapshots__/require-yield.test.ts.snap

@@ -669,7 +669,7 @@ class A { @dec *foo() { return 0; } }",
           "line": 2,
         },
         "start": {
-          "column": 11,
+          "column": 16,
           "line": 2,
         },
       },
@@ -696,7 +696,7 @@ class A { @dec() *foo() { return 0; } }",
           "line": 2,
         },
         "start": {
-          "column": 11,
+          "column": 18,
           "line": 2,
         },
       },
@@ -723,7 +723,7 @@ class A { @d1 @d2 *foo() { return 0; } }",
           "line": 2,
         },
         "start": {
-          "column": 11,
+          "column": 19,
           "line": 2,
         },
       },
@@ -750,7 +750,7 @@ class A { @dec public static *foo() { return 0; } }",
           "line": 2,
         },
         "start": {
-          "column": 11,
+          "column": 16,
           "line": 2,
         },
       },
@@ -777,7 +777,7 @@ class A { @dec async *foo() { return 0; } }",
           "line": 2,
         },
         "start": {
-          "column": 11,
+          "column": 16,
           "line": 2,
         },
       },
@@ -832,7 +832,7 @@ class A { @dec foo = function*() { return 0; }; }",
           "line": 2,
         },
         "start": {
-          "column": 11,
+          "column": 16,
           "line": 2,
         },
       },
@@ -863,7 +863,7 @@ class A {
         },
         "start": {
           "column": 3,
-          "line": 3,
+          "line": 4,
         },
       },
       "ruleName": "require-yield",

packages/rslint-test-tools/tests/eslint/rules/require-yield.test.ts

@@ -443,13 +443,16 @@ ruleTester.run('require-yield', {
     },
 
     // ---- Decorator scenarios ----
+    // GetFunctionHeadLoc mirrors typescript-eslint's getFunctionHeadLoc,
+    // which excludes leading decorators from the reported range, so the
+    // start column lands on the first token after the last decorator.
     {
       code: 'declare function dec(t: any, k: any, d: any): void;\nclass A { @dec *foo() { return 0; } }',
       errors: [
         {
           messageId: 'missingYield',
           line: 2,
-          column: 11,
+          column: 16,
           endLine: 2,
           endColumn: 20,
         },
@@ -461,7 +464,7 @@ ruleTester.run('require-yield', {
         {
           messageId: 'missingYield',
           line: 2,
-          column: 11,
+          column: 18,
           endLine: 2,
           endColumn: 22,
         },
@@ -473,7 +476,7 @@ ruleTester.run('require-yield', {
         {
           messageId: 'missingYield',
           line: 2,
-          column: 11,
+          column: 19,
           endLine: 2,
           endColumn: 23,
         },
@@ -485,7 +488,7 @@ ruleTester.run('require-yield', {
         {
           messageId: 'missingYield',
           line: 2,
-          column: 11,
+          column: 16,
           endLine: 2,
           endColumn: 34,
         },
@@ -497,7 +500,7 @@ ruleTester.run('require-yield', {
         {
           messageId: 'missingYield',
           line: 2,
-          column: 11,
+          column: 16,
           endLine: 2,
           endColumn: 26,
         },
@@ -521,7 +524,7 @@ ruleTester.run('require-yield', {
         {
           messageId: 'missingYield',
           line: 2,
-          column: 11,
+          column: 16,
           endLine: 2,
           endColumn: 31,
         },
@@ -532,7 +535,7 @@ ruleTester.run('require-yield', {
       errors: [
         {
           messageId: 'missingYield',
-          line: 3,
+          line: 4,
           column: 3,
           endLine: 4,
           endColumn: 7,