merge the "const" and "let" features

Author: evanw

internal/compat/js_table.go

@@ -60,7 +60,7 @@ const (
 	ClassPrivateStaticMethod
 	ClassStaticBlocks
 	ClassStaticField
-	Const
+	ConstAndLet
 	DefaultArgument
 	Destructuring
 	DynamicImport
@@ -72,7 +72,6 @@ const (
 	Hashbang
 	ImportAssertions
 	ImportMeta
-	Let
 	LogicalAssignment
 	NestedRestBinding
 	NewTarget
@@ -266,7 +265,7 @@ var jsTable = map[JSFeature]map[Engine][]versionRange{
 		Opera:   {{start: v{60, 0, 0}}},
 		Safari:  {{start: v{14, 1, 0}}},
 	},
-	Const: {
+	ConstAndLet: {
 		Chrome:  {{start: v{49, 0, 0}}},
 		Edge:    {{start: v{14, 0, 0}}},
 		ES:      {{start: v{2015, 0, 0}}},
@@ -378,17 +377,6 @@ var jsTable = map[JSFeature]map[Engine][]versionRange{
 		Opera:   {{start: v{51, 0, 0}}},
 		Safari:  {{start: v{11, 1, 0}}},
 	},
-	Let: {
-		Chrome:  {{start: v{49, 0, 0}}},
-		Edge:    {{start: v{14, 0, 0}}},
-		ES:      {{start: v{2015, 0, 0}}},
-		Firefox: {{start: v{51, 0, 0}}},
-		IE:      {{start: v{11, 0, 0}}},
-		IOS:     {{start: v{11, 0, 0}}},
-		Node:    {{start: v{6, 0, 0}}},
-		Opera:   {{start: v{36, 0, 0}}},
-		Safari:  {{start: v{11, 0, 0}}},
-	},
 	LogicalAssignment: {
 		Chrome:  {{start: v{85, 0, 0}}},
 		Edge:    {{start: v{85, 0, 0}}},

internal/js_parser/js_parser.go

@@ -4299,7 +4299,7 @@ func (p *parser) parseExprOrLetStmt(opts parseStmtOpts) (js_ast.Expr, js_ast.Stm
 			if opts.lexicalDecl != lexicalDeclAllowAll {
 				p.forbidLexicalDecl(letRange.Loc)
 			}
-			p.markSyntaxFeature(compat.Let, letRange)
+			p.markSyntaxFeature(compat.ConstAndLet, letRange)
 			decls := p.parseAndDeclareDecls(js_ast.SymbolOther, opts)
 			return js_ast.Expr{}, js_ast.Stmt{Loc: letRange.Loc, Data: &js_ast.SLocal{
 				Kind:     js_ast.LocalLet,
@@ -6193,7 +6193,7 @@ func (p *parser) parseStmt(opts parseStmtOpts) js_ast.Stmt {
 		if opts.lexicalDecl != lexicalDeclAllowAll {
 			p.forbidLexicalDecl(loc)
 		}
-		p.markSyntaxFeature(compat.Const, p.lexer.Range())
+		p.markSyntaxFeature(compat.ConstAndLet, p.lexer.Range())
 		p.lexer.Next()
 
 		if p.options.ts.Parse && p.lexer.Token == js_lexer.TEnum {
@@ -6442,7 +6442,7 @@ func (p *parser) parseStmt(opts parseStmtOpts) js_ast.Stmt {
 			initOrNil = js_ast.Stmt{Loc: initLoc, Data: &js_ast.SLocal{Kind: js_ast.LocalVar, Decls: decls}}
 
 		case js_lexer.TConst:
-			p.markSyntaxFeature(compat.Const, p.lexer.Range())
+			p.markSyntaxFeature(compat.ConstAndLet, p.lexer.Range())
 			p.lexer.Next()
 			decls = p.parseAndDeclareDecls(js_ast.SymbolConst, parseStmtOpts{})
 			initOrNil = js_ast.Stmt{Loc: initLoc, Data: &js_ast.SLocal{Kind: js_ast.LocalConst, Decls: decls}}
@@ -7523,7 +7523,7 @@ func (p *parser) visitStmts(stmts []js_ast.Stmt, kind stmtsKind) []js_ast.Stmt {
 		// Reuse memory from "before"
 		before = before[:0]
 		kind := js_ast.LocalLet
-		if p.options.unsupportedJSFeatures.Has(compat.Let) {
+		if p.options.unsupportedJSFeatures.Has(compat.ConstAndLet) {
 			kind = js_ast.LocalVar
 		}
 		if len(letDecls) > 0 {

internal/js_parser/js_parser_lower.go

@@ -71,11 +71,8 @@ func (p *parser) markSyntaxFeature(feature compat.JSFeature, r logger.Range) (di
 	case compat.NewTarget:
 		name = "new.target"
 
-	case compat.Const:
-		name = "const"
-
-	case compat.Let:
-		name = "let"
+	case compat.ConstAndLet:
+		name = p.source.TextForRange(r)
 
 	case compat.Class:
 		name = "class syntax"

internal/runtime/runtime.go

@@ -16,7 +16,7 @@ import (
 const SourceIndex = uint32(0)
 
 func CanUseES6(unsupportedFeatures compat.JSFeature) bool {
-	return !unsupportedFeatures.Has(compat.Let) && !unsupportedFeatures.Has(compat.ForOf)
+	return !unsupportedFeatures.Has(compat.ConstAndLet) && !unsupportedFeatures.Has(compat.ForOf)
 }
 
 func code(isES6 bool) string {

scripts/compat-table.js

@@ -31,8 +31,8 @@ const features = {
   'destructuring, assignment': { target: 'Destructuring' },
   'destructuring, parameters': { target: 'Destructuring' },
   'new.target': { target: 'NewTarget' },
-  'const': { target: 'Const' },
-  'let': { target: 'Let' },
+  'const': { target: 'ConstAndLet' },
+  'let': { target: 'ConstAndLet' },
   'arrow functions': { target: 'Arrow' },
   'class': { target: 'Class' },
   'generators': { target: 'Generator' },
@@ -135,13 +135,12 @@ mergeVersions('ObjectAccessors', { es5: true })
 mergeVersions('ArraySpread', { es2015: true })
 mergeVersions('Arrow', { es2015: true })
 mergeVersions('Class', { es2015: true })
-mergeVersions('Const', { es2015: true })
+mergeVersions('ConstAndLet', { es2015: true })
 mergeVersions('DefaultArgument', { es2015: true })
 mergeVersions('Destructuring', { es2015: true })
 mergeVersions('DynamicImport', { es2015: true })
 mergeVersions('ForOf', { es2015: true })
 mergeVersions('Generator', { es2015: true })
-mergeVersions('Let', { es2015: true })
 mergeVersions('NewTarget', { es2015: true })
 mergeVersions('ObjectExtensions', { es2015: true })
 mergeVersions('RegExpStickyAndUnicodeFlags', { es2015: true })