fix #3490, close #3491: import type from from ""

CHANGELOG.md

@@ -35,6 +35,18 @@
     document.onkeydown=o=>o.keyCode===65&&console.log("🧀");
     ```
 
+* Parse an upcoming change to TypeScript type syntax ([#3490](https://github.com/evanw/esbuild/issues/3490), [#3491](https://github.com/evanw/esbuild/pull/3491))
+
+    With this release, you can now use `from` as the name of a default type-only import in TypeScript code:
+
+    ```ts
+    import type from from 'from'
+    ```
+
+    This matches a similar [change in the TypeScript compiler](https://github.com/microsoft/TypeScript/issues/56376) which will start allowing this syntax in an upcoming version of TypeScript.
+
+    This change was contributed by [@magic-akari](https://github.com/magic-akari).
+
 ## 0.19.5
 
 * Fix a regression in 0.19.0 regarding `paths` in `tsconfig.json` ([#3354](https://github.com/evanw/esbuild/issues/3354))

internal/js_parser/js_parser.go

@@ -7491,6 +7491,7 @@ func (p *parser) parseStmt(opts parseStmtOpts) js_ast.Stmt {
 			p.lexer.Expected(js_lexer.TIdentifier)
 		}
 
+	syntaxBeforePath:
 		switch p.lexer.Token {
 		case js_lexer.TOpenParen, js_lexer.TDot:
 			// "import('path')"
@@ -7553,22 +7554,23 @@ func (p *parser) parseStmt(opts parseStmtOpts) js_ast.Stmt {
 				if defaultName.String == "type" {
 					switch p.lexer.Token {
 					case js_lexer.TIdentifier:
-						if p.lexer.Identifier.String != "from" {
-							defaultName = p.lexer.Identifier
-							stmt.DefaultName.Loc = p.lexer.Loc()
-							p.lexer.Next()
-							if p.lexer.Token == js_lexer.TEquals {
-								// "import type foo = require('bar');"
-								// "import type foo = bar.baz;"
-								opts.isTypeScriptDeclare = true
-								return p.parseTypeScriptImportEqualsStmt(loc, opts, stmt.DefaultName.Loc, defaultName.String)
-							} else {
-								// "import type foo from 'bar';"
-								p.lexer.ExpectContextualKeyword("from")
-								p.parsePath()
-								p.lexer.ExpectOrInsertSemicolon()
-								return js_ast.Stmt{Loc: loc, Data: js_ast.STypeScriptShared}
-							}
+						nameSubstring := p.lexer.Identifier
+						nameLoc := p.lexer.Loc()
+						p.lexer.Next()
+						if p.lexer.Token == js_lexer.TEquals {
+							// "import type foo = require('bar');"
+							// "import type foo = bar.baz;"
+							opts.isTypeScriptDeclare = true
+							return p.parseTypeScriptImportEqualsStmt(loc, opts, nameLoc, nameSubstring.String)
+						} else if p.lexer.Token == js_lexer.TStringLiteral && nameSubstring.String == "from" {
+							// "import type from 'bar';"
+							break syntaxBeforePath
+						} else {
+							// "import type foo from 'bar';"
+							p.lexer.ExpectContextualKeyword("from")
+							p.parsePath()
+							p.lexer.ExpectOrInsertSemicolon()
+							return js_ast.Stmt{Loc: loc, Data: js_ast.STypeScriptShared}
 						}
 
 					case js_lexer.TAsterisk:

internal/js_parser/ts_parser_test.go

@@ -2540,12 +2540,14 @@ func TestTSImportEqualsInNamespace(t *testing.T) {
 func TestTSTypeOnlyImport(t *testing.T) {
 	expectPrintedTS(t, "import type foo from 'bar'; x", "x;\n")
 	expectPrintedTS(t, "import type foo from 'bar'\nx", "x;\n")
+	expectPrintedTS(t, "import type from from 'bar'; x", "x;\n")
 	expectPrintedTS(t, "import type * as foo from 'bar'; x", "x;\n")
 	expectPrintedTS(t, "import type * as foo from 'bar'\nx", "x;\n")
 	expectPrintedTS(t, "import type {foo, bar as baz} from 'bar'; x", "x;\n")
 	expectPrintedTS(t, "import type {'foo' as bar} from 'bar'\nx", "x;\n")
 	expectPrintedTS(t, "import type foo = require('bar'); x", "x;\n")
 	expectPrintedTS(t, "import type foo = bar.baz; x", "x;\n")
+	expectPrintedTS(t, "import type from = require('bar'); x", "x;\n")
 
 	expectPrintedTS(t, "import type = bar; type", "const type = bar;\ntype;\n")
 	expectPrintedTS(t, "import type = foo.bar; type", "const type = foo.bar;\ntype;\n")
@@ -2578,6 +2580,8 @@ func TestTSTypeOnlyImport(t *testing.T) {
 
 	expectParseErrorTS(t, "import type foo, * as foo from 'bar'", "<stdin>: ERROR: Expected \"from\" but found \",\"\n")
 	expectParseErrorTS(t, "import type foo, {foo} from 'bar'", "<stdin>: ERROR: Expected \"from\" but found \",\"\n")
+	expectParseErrorTS(t, "import type from, * as foo from 'bar'", "<stdin>: ERROR: Expected \"from\" but found \",\"\n")
+	expectParseErrorTS(t, "import type from, {foo} from 'bar'", "<stdin>: ERROR: Expected \"from\" but found \",\"\n")
 	expectParseErrorTS(t, "import type * as foo = require('bar')", "<stdin>: ERROR: Expected \"from\" but found \"=\"\n")
 	expectParseErrorTS(t, "import type {foo} = require('bar')", "<stdin>: ERROR: Expected \"from\" but found \"=\"\n")