some parsing fixes for source phase imports

Author: evanw

CHANGELOG.md

@@ -15,6 +15,18 @@
     }
     ```
 
+* Fix a regression with the parsing of source phase imports
+
+    The change in the previous release to parse [source phase imports](https://github.com/tc39/proposal-source-phase-imports) failed to properly handle the following cases:
+
+    ```ts
+    import source from 'bar'
+    import source from from 'bar'
+    import source type foo from 'bar'
+    ```
+
+    Parsing for these cases should now be fixed. The first case was incorrectly treated as a syntax error because esbuild was expecting the second case. And the last case was previously allowed but is now forbidden. TypeScript hasn't added this feature yet so it remains to be seen whether the last case will be allowed, but it's safer to disallow it for now. At least Babel doesn't allow the last case when parsing TypeScript, and Babel was involved with the source phase import specification.
+
 ## 0.25.7
 
 * Parse and print JavaScript imports with an explicit phase ([#4238](https://github.com/evanw/esbuild/issues/4238))

internal/js_parser/js_parser.go

@@ -7935,12 +7935,30 @@ func (p *parser) parseStmt(opts parseStmtOpts) js_ast.Stmt {
 			}
 
 			if isSourceName && p.lexer.Token == js_lexer.TIdentifier {
+				if p.lexer.Raw() == "from" {
+					nameSubstring := p.lexer.Identifier
+					nameLoc := p.lexer.Loc()
+					p.lexer.Next()
+					if p.lexer.IsContextualKeyword("from") {
+						// "import source from from 'foo';"
+						p.markSyntaxFeature(compat.ImportSource, js_lexer.RangeOfIdentifier(p.source, defaultLoc))
+						phase = ast.SourcePhase
+						stmt.DefaultName = &ast.LocRef{Loc: nameLoc, Ref: p.storeNameInRef(nameSubstring)}
+						p.lexer.Next()
+					} else {
+						// "import source from 'foo';"
+						stmt.DefaultName = &ast.LocRef{Loc: defaultLoc, Ref: p.storeNameInRef(defaultName)}
+					}
+					break
+				}
+
 				// "import source foo from 'bar';"
 				p.markSyntaxFeature(compat.ImportSource, js_lexer.RangeOfIdentifier(p.source, defaultLoc))
 				phase = ast.SourcePhase
-				defaultName = p.lexer.Identifier
-				defaultLoc = p.lexer.Loc()
+				stmt.DefaultName = &ast.LocRef{Loc: p.lexer.Loc(), Ref: p.storeNameInRef(p.lexer.Identifier)}
 				p.lexer.Next()
+				p.lexer.ExpectContextualKeyword("from")
+				break
 			}
 
 			stmt.DefaultName = &ast.LocRef{Loc: defaultLoc, Ref: p.storeNameInRef(defaultName)}

internal/js_parser/js_parser_test.go

@@ -3115,6 +3115,7 @@ func TestImport(t *testing.T) {
 	expectParseError(t, "import * as '' from 'foo'", "<stdin>: ERROR: Expected identifier but found \"''\"\n")
 
 	// See: https://github.com/tc39/proposal-defer-import-eval
+	expectPrinted(t, "import defer from 'bar'", "import defer from \"bar\";\n")
 	expectPrinted(t, "import defer, { foo } from 'bar'", "import defer, { foo } from \"bar\";\n")
 	expectPrinted(t, "import defer * as foo from 'bar'", "import defer * as foo from \"bar\";\n")
 	expectPrinted(t, "import.defer('foo')", "import.defer(\"foo\");\n")
@@ -3125,8 +3126,11 @@ func TestImport(t *testing.T) {
 	expectParseErrorTarget(t, 6, "import.defer('foo')", "<stdin>: ERROR: Deferred imports are not available in the configured target environment\n")
 
 	// See: https://github.com/tc39/proposal-source-phase-imports
+	expectPrinted(t, "import source from 'bar'", "import source from \"bar\";\n")
 	expectPrinted(t, "import source, { foo } from 'bar'", "import source, { foo } from \"bar\";\n")
 	expectPrinted(t, "import source foo from 'bar'", "import source foo from \"bar\";\n")
+	expectPrinted(t, "import source from from 'bar'", "import source from from \"bar\";\n")
+	expectPrinted(t, "import source source from 'bar'", "import source source from \"bar\";\n")
 	expectPrinted(t, "import.source('foo')", "import.source(\"foo\");\n")
 	expectParseError(t, "import source 'bar'", "<stdin>: ERROR: Expected \"from\" but found \"'bar'\"\n")
 	expectParseError(t, "import source * as foo from 'bar'", "<stdin>: ERROR: Expected \"from\" but found \"*\"\n")

internal/js_parser/ts_parser_test.go

@@ -2966,6 +2966,22 @@ func TestTSTypeOnlyImport(t *testing.T) {
 	expectParseErrorTS(t, "import { x, type 'y' as 'z' } from 'mod'", "<stdin>: ERROR: Expected identifier but found \"'z'\"\n")
 	expectParseErrorTS(t, "import { x, type as 'y' } from 'mod'", "<stdin>: ERROR: Expected \"}\" but found \"'y'\"\n")
 	expectParseErrorTS(t, "import { x, type y as 'z' } from 'mod'", "<stdin>: ERROR: Expected identifier but found \"'z'\"\n")
+
+	// See: https://github.com/tc39/proposal-defer-import-eval
+	expectPrintedTS(t, "import defer * as foo from 'bar'", "")
+	expectPrintedTS(t, "import defer * as foo from 'bar'; let x: foo.Type", "let x;\n")
+	expectPrintedTS(t, "import defer * as foo from 'bar'; let x = foo.value", "import defer * as foo from \"bar\";\nlet x = foo.value;\n")
+	expectPrintedTS(t, "import type defer from 'bar'", "")
+	expectParseErrorTS(t, "import type defer * as foo from 'bar'", "<stdin>: ERROR: Expected \"from\" but found \"*\"\n")
+
+	// See: https://github.com/tc39/proposal-source-phase-imports
+	expectPrintedTS(t, "import type source from 'bar'", "")
+	expectPrintedTS(t, "import source foo from 'bar'", "")
+	expectPrintedTS(t, "import source foo from 'bar'; let x: foo", "let x;\n")
+	expectPrintedTS(t, "import source foo from 'bar'; let x = foo", "import source foo from \"bar\";\nlet x = foo;\n")
+	expectPrintedTS(t, "import source type from 'bar'", "")
+	expectParseErrorTS(t, "import source type foo from 'bar'", "<stdin>: ERROR: Expected \"from\" but found \"foo\"\n")
+	expectParseErrorTS(t, "import type source foo from 'bar'", "<stdin>: ERROR: Expected \"from\" but found \"foo\"\n")
 }
 
 func TestTSTypeOnlyExport(t *testing.T) {