Restore import defer = parsing (#61837)

Author: nicolo-ribaudo

src/compiler/parser.ts

@@ -8392,7 +8392,10 @@ namespace Parser {
             phaseModifier = SyntaxKind.TypeKeyword;
             identifier = isIdentifier() ? parseIdentifier() : undefined;
         }
-        else if (identifier?.escapedText === "defer" && token() !== SyntaxKind.FromKeyword) {
+        else if (
+            identifier?.escapedText === "defer" &&
+            (token() === SyntaxKind.FromKeyword ? !lookAhead(nextTokenIsStringLiteral) : token() !== SyntaxKind.CommaToken && token() !== SyntaxKind.EqualsToken)
+        ) {
             phaseModifier = SyntaxKind.DeferKeyword;
             identifier = isIdentifier() ? parseIdentifier() : undefined;
         }

tests/baselines/reference/importBindingDefer.js

@@ -0,0 +1,13 @@
+//// [tests/cases/conformance/importDefer/importBindingDefer.ts] ////
+
+//// [a.ts]
+export default 2;
+
+//// [b.ts]
+import defer from "./a.js";
+
+
+//// [a.js]
+export default 2;
+//// [b.js]
+export {};

tests/baselines/reference/importBindingDefer.symbols

@@ -0,0 +1,10 @@
+//// [tests/cases/conformance/importDefer/importBindingDefer.ts] ////
+
+=== a.ts ===
+
+export default 2;
+
+=== b.ts ===
+import defer from "./a.js";
+>defer : Symbol(defer, Decl(b.ts, 0, 6))
+

tests/baselines/reference/importBindingDefer.types

@@ -0,0 +1,11 @@
+//// [tests/cases/conformance/importDefer/importBindingDefer.ts] ////
+
+=== a.ts ===
+
+export default 2;
+
+=== b.ts ===
+import defer from "./a.js";
+>defer : 2
+>      : ^
+

tests/baselines/reference/importBindingDefer2.js

@@ -0,0 +1,13 @@
+//// [tests/cases/conformance/importDefer/importBindingDefer2.ts] ////
+
+//// [a.ts]
+export default 2;
+
+//// [b.ts]
+import defer, {} from "./a.js";
+
+
+//// [a.js]
+export default 2;
+//// [b.js]
+export {};

tests/baselines/reference/importBindingDefer2.symbols

@@ -0,0 +1,10 @@
+//// [tests/cases/conformance/importDefer/importBindingDefer2.ts] ////
+
+=== a.ts ===
+
+export default 2;
+
+=== b.ts ===
+import defer, {} from "./a.js";
+>defer : Symbol(defer, Decl(b.ts, 0, 6))
+

tests/baselines/reference/importBindingDefer2.types

@@ -0,0 +1,11 @@
+//// [tests/cases/conformance/importDefer/importBindingDefer2.ts] ////
+
+=== a.ts ===
+
+export default 2;
+
+=== b.ts ===
+import defer, {} from "./a.js";
+>defer : 2
+>      : ^
+

tests/baselines/reference/importDeferFromInvalid.errors.txt

@@ -0,0 +1,11 @@
+b.ts(1,8): error TS18058: Default imports are not allowed in a deferred import.
+
+
+==== a.ts (0 errors) ====
+    export default 2;
+    
+==== b.ts (1 errors) ====
+    import defer from from "./a.js";
+           ~~~~~~~~~~
+!!! error TS18058: Default imports are not allowed in a deferred import.
+    

tests/baselines/reference/importDeferFromInvalid.js

@@ -0,0 +1,13 @@
+//// [tests/cases/conformance/importDefer/importDeferFromInvalid.ts] ////
+
+//// [a.ts]
+export default 2;
+
+//// [b.ts]
+import defer from from "./a.js";
+
+
+//// [a.js]
+export default 2;
+//// [b.js]
+export {};

tests/baselines/reference/importDeferFromInvalid.symbols

@@ -0,0 +1,10 @@
+//// [tests/cases/conformance/importDefer/importDeferFromInvalid.ts] ////
+
+=== a.ts ===
+
+export default 2;
+
+=== b.ts ===
+import defer from from "./a.js";
+>from : Symbol(from, Decl(b.ts, 0, 6))
+