Fix specifiers for declaration files (#3351)

Author: jakebailey

internal/ls/string_completions.go

@@ -1813,7 +1813,7 @@ func getFilenameWithExtensionOption(
 	extensionOptions *extensionOptions,
 	isExportsOrImportsWildcard bool,
 ) (string, string) {
-	nonJSResult := tryGetRealFileNameForNonJSDeclarationFileName(name)
+	nonJSResult := modulespecifiers.TryGetRealFileNameForNonJSDeclarationFileName(name)
 	if nonJSResult != "" {
 		return nonJSResult, tspath.TryGetExtensionFromPath(nonJSResult)
 	}
@@ -1863,22 +1863,6 @@ func getFilenameWithExtensionOption(
 	return name, tspath.TryGetExtensionFromPath(name)
 }
 
-// Remaps files like `foo.d.json.ts` back to `foo.json`.
-func tryGetRealFileNameForNonJSDeclarationFileName(fileName string) string {
-	baseName := tspath.GetBaseFileName(fileName)
-	// Ends with .ts, contains ".d.", and is NOT a standard .d.ts file
-	if !strings.HasSuffix(fileName, tspath.ExtensionTs) ||
-		!strings.Contains(baseName, ".d.") ||
-		strings.HasSuffix(baseName, tspath.ExtensionDts) {
-		return ""
-	}
-	noExtension := tspath.RemoveExtension(fileName, tspath.ExtensionTs)
-	lastDotIndex := strings.LastIndex(noExtension, ".")
-	ext := noExtension[lastDotIndex:]
-	before, _, _ := strings.Cut(noExtension, ".d.")
-	return before + ext
-}
-
 func walkUpParentheses(node *ast.Node) *ast.Node {
 	switch node.Kind {
 	case ast.KindParenthesizedType:

internal/modulespecifiers/specifiers.go

@@ -661,6 +661,12 @@ func processEnding(
 	if tspath.FileExtensionIsOneOf(fileName, []string{tspath.ExtensionMts, tspath.ExtensionCts}) {
 		return noExtension + getJSExtensionForFile(fileName, options)
 	}
+	if !tspath.FileExtensionIsOneOf(fileName, []string{tspath.ExtensionDts}) && tspath.FileExtensionIsOneOf(fileName, []string{tspath.ExtensionTs}) && strings.Contains(fileName, ".d.") {
+		// `foo.d.json.ts` and the like - remap back to `foo.json`
+		if result := TryGetRealFileNameForNonJSDeclarationFileName(fileName); result != "" {
+			return result
+		}
+	}
 
 	switch allowedEndings[0] {
 	case ModuleSpecifierEndingMinimal:
@@ -676,10 +682,21 @@ func processEnding(
 	case ModuleSpecifierEndingJsExtension:
 		return noExtension + getJSExtensionForFile(fileName, options)
 	case ModuleSpecifierEndingTsExtension:
-		// declaration files are already handled first with a remap back to input js paths,
-		// and mjs/cjs/json are already singled out,
-		// so we know fileName has to be either an input .js or .ts path already
-		// TODO: possible dead code in strada in this branch to do with declaration file name handling
+		// For now, we don't know if this import is going to be type-only, which means we don't
+		// know if a .d.ts extension is valid, so use no extension or a .js extension
+		if tspath.IsDeclarationFileName(fileName) {
+			extensionlessPriority := -1
+			for i, e := range allowedEndings {
+				if e == ModuleSpecifierEndingMinimal || e == ModuleSpecifierEndingIndex {
+					extensionlessPriority = i
+					break
+				}
+			}
+			if extensionlessPriority != -1 && extensionlessPriority < jsPriority {
+				return noExtension
+			}
+			return noExtension + getJSExtensionForFile(fileName, options)
+		}
 		return fileName
 	default:
 		debug.AssertNever(allowedEndings[0])

internal/modulespecifiers/specifiers_test.go

@@ -257,6 +257,40 @@ func TestContainsIgnoredPath(t *testing.T) {
 	}
 }
 
+func TestTryGetRealFileNameForNonJSDeclarationFileName(t *testing.T) {
+	t.Parallel()
+	tests := []struct {
+		name     string
+		fileName string
+		expected string
+	}{
+		{
+			name:     "json declaration file",
+			fileName: "/project/foo.d.json.ts",
+			expected: "/project/foo.json",
+		},
+		{
+			name:     "multi-dot source extension declaration file",
+			fileName: "/project/foo.module.d.css.ts",
+			expected: "/project/foo.module.css",
+		},
+		{
+			name:     "plain dts file ignored",
+			fileName: "/project/foo.d.ts",
+			expected: "",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+			if got := TryGetRealFileNameForNonJSDeclarationFileName(tt.fileName); got != tt.expected {
+				t.Errorf("TryGetRealFileNameForNonJSDeclarationFileName(%q) = %q, expected %q", tt.fileName, got, tt.expected)
+			}
+		})
+	}
+}
+
 func TestTryGetModuleNameFromExportsOrImports(t *testing.T) {
 	t.Parallel()
 	t.Run("with exports pattern", func(t *testing.T) {

internal/modulespecifiers/util.go

@@ -151,6 +151,23 @@ func GetJSExtensionForDeclarationFileExtension(ext string) string {
 	}
 }
 
+// TryGetRealFileNameForNonJSDeclarationFileName remaps files like `foo.d.json.ts` or
+// `foo.module.d.css.ts` back to their real non-JS names.
+func TryGetRealFileNameForNonJSDeclarationFileName(fileName string) string {
+	baseName := tspath.GetBaseFileName(fileName)
+	// Ends with .ts, contains ".d.", and is NOT a standard .d.ts file
+	if !strings.HasSuffix(fileName, tspath.ExtensionTs) ||
+		!strings.Contains(baseName, ".d.") ||
+		strings.HasSuffix(baseName, tspath.ExtensionDts) {
+		return ""
+	}
+	noExtension := tspath.RemoveExtension(fileName, tspath.ExtensionTs)
+	lastDotIndex := strings.LastIndex(noExtension, ".")
+	ext := noExtension[lastDotIndex:]
+	before, _, _ := strings.Cut(noExtension, ".d.")
+	return before + ext
+}
+
 func getJSExtensionForFile(fileName string, options *core.CompilerOptions) string {
 	result := module.TryGetJSExtensionForFile(fileName, options)
 	if len(result) == 0 {

testdata/baselines/reference/submodule/compiler/declarationEmitNoInvalidCommentReuse2.js

@@ -22,7 +22,7 @@ export type Id<T> = T;
 
 //// [a.d.ts]
 export declare const _: {
-    foo: import("./id.d.ts").Id<{}>;
+    foo: import("./id").Id<{}>;
 };
 /**
  * huh

testdata/baselines/reference/submodule/compiler/declarationEmitNoInvalidCommentReuse2.js.diff

@@ -2,11 +2,11 @@
 
 === a.ts ===
 import { object } from "./obj.ts";
->object : { foo: import("./id.d.ts").Id<{}>; }
+>object : { foo: import("./id").Id<{}>; }
 
 export const _ = object;
->_ : { foo: import("./id.d.ts").Id<{}>; }
->object : { foo: import("./id.d.ts").Id<{}>; }
+>_ : { foo: import("./id").Id<{}>; }
+>object : { foo: import("./id").Id<{}>; }
 
 ///////////
 /**

testdata/baselines/reference/submodule/compiler/declarationEmitNoInvalidCommentReuse2.types

@@ -34,4 +34,4 @@ exports.c = (0, reexporter_1.func)();
 import { CustomHtmlRepresentationThing } from "./foo.html";
 export declare function func(): CustomHtmlRepresentationThing;
 //// [index.d.ts]
-export declare const c: import("./foo.d.html").CustomHtmlRepresentationThing;
+export declare const c: import("./foo.html").CustomHtmlRepresentationThing;