fix #277: respect "target" in "tsconfig.json"

CHANGELOG.md

@@ -10,6 +10,10 @@
 
     This release contains a potential fix for an unverified issue with non-determinism in esbuild. The regression was apparently introduced in 0.11.13 and may be related to parallelism that was introduced around the point where dynamic `import()` expressions are added to the list of entry points. Hopefully this fix should resolve the regression.
 
+* Respect `target` in `tsconfig.json` ([#277](https://github.com/evanw/esbuild/issues/277))
+
+    Each JavaScript file that esbuild bundles will now be transformed according to the [`target`](https://www.typescriptlang.org/tsconfig#target) language level from the nearest enclosing `tsconfig.json` file. This is in addition to esbuild's own `--target` setting; the two settings are merged by transforming any JavaScript language feature that is unsupported in either esbuild's configured `--target` value or the `target` property in the `tsconfig.json` file.
+
 ## 0.12.3
 
 * Ensure JSX element names start with a capital letter ([#1309](https://github.com/evanw/esbuild/issues/1309))

internal/bundler/bundler.go

@@ -1068,6 +1068,7 @@ func (s *scanner) maybeParseFile(
 	if resolveResult.PreserveUnusedImportsTS {
 		optionsClone.PreserveUnusedImportsTS = true
 	}
+	optionsClone.TSTarget = resolveResult.TSTarget
 
 	// Set the module type preference using node's module type rules
 	if strings.HasSuffix(path.Text, ".mjs") {

internal/bundler/bundler_tsconfig_test.go

@@ -1097,3 +1097,84 @@ func TestTsconfigPreserveUnusedImportClause(t *testing.T) {
 		},
 	})
 }
+
+func TestTsconfigTarget(t *testing.T) {
+	tsconfig_suite.expectBundled(t, bundled{
+		files: map[string]string{
+			"/Users/user/project/src/entry.ts": `
+				import "./es2018"
+				import "./es2019"
+				import "./es2020"
+				import "./es4"
+			`,
+			"/Users/user/project/src/es2018/index.ts": `
+				let x = { ...y }   // es2018 syntax
+				try { y } catch {} // es2019 syntax
+				x?.y()             // es2020 syntax
+			`,
+			"/Users/user/project/src/es2019/index.ts": `
+				let x = { ...y }   // es2018 syntax
+				try { y } catch {} // es2019 syntax
+				x?.y()             // es2020 syntax
+			`,
+			"/Users/user/project/src/es2020/index.ts": `
+				let x = { ...y }   // es2018 syntax
+				try { y } catch {} // es2019 syntax
+				x?.y()             // es2020 syntax
+			`,
+			"/Users/user/project/src/es4/index.ts": `
+			`,
+			"/Users/user/project/src/es2018/tsconfig.json": `{
+				"compilerOptions": {
+					"target": "ES2018"
+				}
+			}`,
+			"/Users/user/project/src/es2019/tsconfig.json": `{
+				"compilerOptions": {
+					"target": "es2019"
+				}
+			}`,
+			"/Users/user/project/src/es2020/tsconfig.json": `{
+				"compilerOptions": {
+					"target": "ESNext"
+				}
+			}`,
+			"/Users/user/project/src/es4/tsconfig.json": `{
+				"compilerOptions": {
+					"target": "ES4"
+				}
+			}`,
+		},
+		entryPaths: []string{"/Users/user/project/src/entry.ts"},
+		options: config.Options{
+			Mode:          config.ModeBundle,
+			AbsOutputFile: "/Users/user/project/out.js",
+		},
+		expectedScanLog: `Users/user/project/src/es4/tsconfig.json: warning: Unrecognized target environment "ES4"
+`,
+	})
+}
+
+func TestTsconfigTargetError(t *testing.T) {
+	tsconfig_suite.expectBundled(t, bundled{
+		files: map[string]string{
+			"/Users/user/project/src/entry.ts": `
+				x = 123n
+			`,
+			"/Users/user/project/src/tsconfig.json": `{
+				"compilerOptions": {
+					"target": "ES2019"
+				}
+			}`,
+		},
+		entryPaths: []string{"/Users/user/project/src/entry.ts"},
+		options: config.Options{
+			Mode:              config.ModeBundle,
+			AbsOutputFile:     "/Users/user/project/out.js",
+			OriginalTargetEnv: "\"esnext\"", // This should not be reported as the cause of the error
+		},
+		expectedScanLog: `Users/user/project/src/entry.ts: error: Big integer literals are not available in the configured target environment ("ES2019")
+Users/user/project/src/tsconfig.json: note: The target environment was set to "ES2019" here
+`,
+	})
+}

internal/bundler/snapshots/snapshots_tsconfig.txt

@@ -334,6 +334,33 @@ TestTsconfigRemoveUnusedImports
 // Users/user/project/src/entry.ts
 console.log(1);
 
+================================================================================
+TestTsconfigTarget
+---------- /Users/user/project/out.js ----------
+// Users/user/project/src/es2018/index.ts
+var x = { ...y };
+try {
+  y;
+} catch (e) {
+}
+x == null ? void 0 : x.y();
+
+// Users/user/project/src/es2019/index.ts
+var x2 = { ...y };
+try {
+  y;
+} catch {
+}
+x2 == null ? void 0 : x2.y();
+
+// Users/user/project/src/es2020/index.ts
+var x3 = { ...y };
+try {
+  y;
+} catch {
+}
+x3?.y();
+
 ================================================================================
 TestTsconfigWarningsInsideNodeModules
 ---------- /Users/user/project/out.js ----------

internal/config/config.go

@@ -226,6 +226,7 @@ type Options struct {
 
 	UnsupportedJSFeatures  compat.JSFeature
 	UnsupportedCSSFeatures compat.CSSFeature
+	TSTarget               *TSTarget
 
 	// This is the original information that was used to generate the
 	// unsupported feature sets above. It's used for error messages.
@@ -271,6 +272,13 @@ type Options struct {
 	Stdin *StdinInfo
 }
 
+type TSTarget struct {
+	Source                logger.Source
+	Range                 logger.Range
+	Target                string
+	UnsupportedJSFeatures compat.JSFeature
+}
+
 type PathPlaceholder uint8
 
 const (

internal/js_parser/js_parser.go

@@ -304,6 +304,7 @@ type thenCatchChain struct {
 type Options struct {
 	injectedFiles []config.InjectedFile
 	jsx           config.JSXOptions
+	tsTarget      *config.TSTarget
 
 	// This pointer will always be different for each build but the contents
 	// shouldn't ever behave different semantically. We ignore this field for the
@@ -341,6 +342,7 @@ func OptionsFromConfig(options *config.Options) Options {
 		injectedFiles: options.InjectedFiles,
 		jsx:           options.JSX,
 		defines:       options.Defines,
+		tsTarget:      options.TSTarget,
 		optionsThatSupportStructuralEquality: optionsThatSupportStructuralEquality{
 			unsupportedJSFeatures:   options.UnsupportedJSFeatures,
 			originalTargetEnv:       options.OriginalTargetEnv,
@@ -367,6 +369,12 @@ func (a *Options) Equal(b *Options) bool {
 		return false
 	}
 
+	// Compare "TSTarget"
+	if (a.tsTarget == nil && b.tsTarget != nil) || (a.tsTarget != nil && b.tsTarget == nil) ||
+		(a.tsTarget != nil && b.tsTarget != nil && *a.tsTarget != *b.tsTarget) {
+		return false
+	}
+
 	// Compare "InjectedFiles"
 	if len(a.injectedFiles) != len(b.injectedFiles) {
 		return false
@@ -13624,6 +13632,11 @@ func Parse(log logger.Log, source logger.Source, options Options) (result js_ast
 		options.useDefineForClassFields = config.False
 	}
 
+	// Include unsupported JavaScript features from the TypeScript "target" setting
+	if options.tsTarget != nil {
+		options.unsupportedJSFeatures |= options.tsTarget.UnsupportedJSFeatures
+	}
+
 	p := newParser(log, source, js_lexer.NewLexer(log, source), &options)
 
 	// Consume a leading hashbang comment

internal/js_parser/js_parser_lower.go

@@ -29,9 +29,15 @@ func (p *parser) markSyntaxFeature(feature compat.JSFeature, r logger.Range) (di
 	}
 
 	var name string
+	var notes []logger.MsgData
 	where := "the configured target environment"
 
-	if p.options.originalTargetEnv != "" {
+	if tsTarget := p.options.tsTarget; tsTarget != nil && tsTarget.UnsupportedJSFeatures.Has(feature) {
+		tracker := logger.MakeLineColumnTracker(&tsTarget.Source)
+		where = fmt.Sprintf("%s (%q)", where, tsTarget.Target)
+		notes = []logger.MsgData{logger.RangeData(&tracker, tsTarget.Range, fmt.Sprintf(
+			"The target environment was set to %q here", tsTarget.Target))}
+	} else if p.options.originalTargetEnv != "" {
 		where = fmt.Sprintf("%s (%s)", where, p.options.originalTargetEnv)
 	}
 
@@ -88,40 +94,40 @@ func (p *parser) markSyntaxFeature(feature compat.JSFeature, r logger.Range) (di
 		name = "non-identifier array rest patterns"
 
 	case compat.ImportAssertions:
-		p.log.AddRangeError(&p.tracker, r,
-			fmt.Sprintf("Using an arbitrary value as the second argument to \"import()\" is not possible in %s", where))
+		p.log.AddRangeErrorWithNotes(&p.tracker, r, fmt.Sprintf(
+			"Using an arbitrary value as the second argument to \"import()\" is not possible in %s", where), notes)
 		return
 
 	case compat.TopLevelAwait:
-		p.log.AddRangeError(&p.tracker, r,
-			fmt.Sprintf("Top-level await is not available in %s", where))
+		p.log.AddRangeErrorWithNotes(&p.tracker, r, fmt.Sprintf(
+			"Top-level await is not available in %s", where), notes)
 		return
 
 	case compat.ArbitraryModuleNamespaceNames:
-		p.log.AddRangeError(&p.tracker, r,
-			fmt.Sprintf("Using a string as a module namespace identifier name is not supported in %s", where))
+		p.log.AddRangeErrorWithNotes(&p.tracker, r, fmt.Sprintf(
+			"Using a string as a module namespace identifier name is not supported in %s", where), notes)
 		return
 
 	case compat.BigInt:
 		// Transforming these will never be supported
-		p.log.AddRangeError(&p.tracker, r,
-			fmt.Sprintf("Big integer literals are not available in %s", where))
+		p.log.AddRangeErrorWithNotes(&p.tracker, r, fmt.Sprintf(
+			"Big integer literals are not available in %s", where), notes)
 		return
 
 	case compat.ImportMeta:
 		// This can't be polyfilled
-		p.log.AddRangeWarning(&p.tracker, r,
-			fmt.Sprintf("\"import.meta\" is not available in %s and will be empty", where))
+		p.log.AddRangeWarningWithNotes(&p.tracker, r, fmt.Sprintf(
+			"\"import.meta\" is not available in %s and will be empty", where), notes)
 		return
 
 	default:
-		p.log.AddRangeError(&p.tracker, r,
-			fmt.Sprintf("This feature is not available in %s", where))
+		p.log.AddRangeErrorWithNotes(&p.tracker, r, fmt.Sprintf(
+			"This feature is not available in %s", where), notes)
 		return
 	}
 
-	p.log.AddRangeError(&p.tracker, r,
-		fmt.Sprintf("Transforming %s to %s is not supported yet", name, where))
+	p.log.AddRangeErrorWithNotes(&p.tracker, r, fmt.Sprintf(
+		"Transforming %s to %s is not supported yet", name, where), notes)
 	return
 }
 

internal/resolver/resolver.go

@@ -103,6 +103,8 @@ type ResolveResult struct {
 	// effects. This means they should be removed if unused.
 	PrimarySideEffectsData *SideEffectsData
 
+	TSTarget *config.TSTarget
+
 	IsExternal bool
 
 	// If true, the class field transform should use Object.defineProperty().
@@ -501,6 +503,7 @@ func (r resolverQuery) finalizeResolve(result *ResolveResult) {
 					result.JSXFragment = dirInfo.enclosingTSConfigJSON.JSXFragmentFactory
 					result.UseDefineForClassFieldsTS = dirInfo.enclosingTSConfigJSON.UseDefineForClassFields
 					result.PreserveUnusedImportsTS = dirInfo.enclosingTSConfigJSON.PreserveImportsNotUsedAsValues
+					result.TSTarget = dirInfo.enclosingTSConfigJSON.TSTarget
 
 					if r.debugLogs != nil {
 						r.debugLogs.addNote(fmt.Sprintf("This import is under the effect of %q",

internal/resolver/tsconfig_json.go

@@ -5,6 +5,7 @@ import (
 	"strings"
 
 	"github.com/evanw/esbuild/internal/cache"
+	"github.com/evanw/esbuild/internal/compat"
 	"github.com/evanw/esbuild/internal/config"
 	"github.com/evanw/esbuild/internal/js_ast"
 	"github.com/evanw/esbuild/internal/js_lexer"
@@ -35,6 +36,7 @@ type TSConfigJSON struct {
 
 	JSXFactory                     []string
 	JSXFragmentFactory             []string
+	TSTarget                       *config.TSTarget
 	UseDefineForClassFields        config.MaybeBool
 	PreserveImportsNotUsedAsValues bool
 }
@@ -110,6 +112,47 @@ func ParseTSConfigJSON(
 			}
 		}
 
+		// Parse "target"
+		if valueJSON, _, ok := getProperty(compilerOptionsJSON, "target"); ok {
+			if value, ok := getString(valueJSON); ok {
+				constraints := make(map[compat.Engine][]int)
+				r := source.RangeOfString(valueJSON.Loc)
+
+				// See https://www.typescriptlang.org/tsconfig#target
+				switch strings.ToLower(value) {
+				case "es5":
+					constraints[compat.ES] = []int{5}
+				case "es6", "es2015":
+					constraints[compat.ES] = []int{2015}
+				case "es7", "es2016":
+					constraints[compat.ES] = []int{2016}
+				case "es2017":
+					constraints[compat.ES] = []int{2017}
+				case "es2018":
+					constraints[compat.ES] = []int{2018}
+				case "es2019":
+					constraints[compat.ES] = []int{2019}
+				case "es2020":
+					constraints[compat.ES] = []int{2020}
+				case "esnext":
+					// Nothing to do in this case
+				default:
+					log.AddRangeWarning(&tracker, r,
+						fmt.Sprintf("Unrecognized target environment %q", value))
+				}
+
+				// These feature restrictions are merged with esbuild's own restrictions
+				if len(constraints) > 0 {
+					result.TSTarget = &config.TSTarget{
+						Source:                source,
+						Range:                 r,
+						Target:                value,
+						UnsupportedJSFeatures: compat.UnsupportedJSFeatures(constraints),
+					}
+				}
+			}
+		}
+
 		// Parse "importsNotUsedAsValues"
 		if valueJSON, _, ok := getProperty(compilerOptionsJSON, "importsNotUsedAsValues"); ok {
 			if value, ok := getString(valueJSON); ok {

pkg/api/api_impl.go

@@ -1242,6 +1242,7 @@ func transformImpl(input string, transformOpts TransformOptions) TransformResult
 	}
 
 	// Settings from "tsconfig.json" override those
+	var tsTarget *config.TSTarget
 	caches := cache.MakeCacheSet()
 	if transformOpts.TsconfigRaw != "" {
 		source := logger.Source{
@@ -1262,6 +1263,7 @@ func transformImpl(input string, transformOpts TransformOptions) TransformResult
 			if result.PreserveImportsNotUsedAsValues {
 				preserveUnusedImportsTS = true
 			}
+			tsTarget = result.TSTarget
 		}
 	}
 
@@ -1280,6 +1282,7 @@ func transformImpl(input string, transformOpts TransformOptions) TransformResult
 		UnsupportedJSFeatures:   jsFeatures,
 		UnsupportedCSSFeatures:  cssFeatures,
 		OriginalTargetEnv:       targetEnv,
+		TSTarget:                tsTarget,
 		JSX:                     jsx,
 		Defines:                 defines,
 		InjectedDefines:         injectedDefines,