fix(42339): "import" missing in transpiled code when variable typed as unknown

src/compiler/checker.ts

@@ -25318,15 +25318,20 @@ namespace ts {
                         hasComputedNumberProperty = false;
                     }
                     const type = getReducedType(checkExpression(memberDecl.expression));
-                    if (!isValidSpreadType(type)) {
-                        error(memberDecl, Diagnostics.Spread_types_may_only_be_created_from_object_types);
-                        return errorType;
+                    if (isValidSpreadType(type)) {
+                        if (allPropertiesTable) {
+                            checkSpreadPropOverrides(type, allPropertiesTable, memberDecl);
+                        }
+                        offset = propertiesArray.length;
+                        if (spread === errorType) {
+                            continue;
+                        }
+                        spread = getSpreadType(spread, type, node.symbol, objectFlags, inConstContext);
                     }
-                    if (allPropertiesTable) {
-                        checkSpreadPropOverrides(type, allPropertiesTable, memberDecl);
+                    else {
+                        error(memberDecl, Diagnostics.Spread_types_may_only_be_created_from_object_types);
+                        spread = errorType;
                     }
-                    spread = getSpreadType(spread, type, node.symbol, objectFlags, inConstContext);
-                    offset = propertiesArray.length;
                     continue;
                 }
                 else {
@@ -25375,6 +25380,10 @@ namespace ts {
                 }
             }
 
+            if (spread === errorType) {
+                return errorType;
+            }
+
             if (spread !== emptyObjectType) {
                 if (propertiesArray.length > 0) {
                     spread = getSpreadType(spread, createObjectLiteralType(), node.symbol, objectFlags, inConstContext);

tests/baselines/reference/spreadUnion3.errors.txt

@@ -2,10 +2,11 @@ tests/cases/conformance/types/spread/spreadUnion3.ts(2,14): error TS2322: Type '
 tests/cases/conformance/types/spread/spreadUnion3.ts(9,9): error TS2322: Type 'number | undefined' is not assignable to type 'number'.
   Type 'undefined' is not assignable to type 'number'.
 tests/cases/conformance/types/spread/spreadUnion3.ts(17,11): error TS2698: Spread types may only be created from object types.
+tests/cases/conformance/types/spread/spreadUnion3.ts(17,37): error TS2698: Spread types may only be created from object types.
 tests/cases/conformance/types/spread/spreadUnion3.ts(18,11): error TS2698: Spread types may only be created from object types.
 
 
-==== tests/cases/conformance/types/spread/spreadUnion3.ts (4 errors) ====
+==== tests/cases/conformance/types/spread/spreadUnion3.ts (5 errors) ====
     function f(x: { y: string } | undefined): { y: string } {
         return { y: 123, ...x } // y: string | number
                  ~
@@ -30,6 +31,8 @@ tests/cases/conformance/types/spread/spreadUnion3.ts(18,11): error TS2698: Sprea
     declare const nullAndUndefinedUnion: null | undefined;
     var x = { ...nullAndUndefinedUnion, ...nullAndUndefinedUnion };
               ~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS2698: Spread types may only be created from object types.
+                                        ~~~~~~~~~~~~~~~~~~~~~~~~
 !!! error TS2698: Spread types may only be created from object types.
     var y = { ...nullAndUndefinedUnion };
               ~~~~~~~~~~~~~~~~~~~~~~~~

tests/baselines/reference/unusedImportWithSpread.js

@@ -0,0 +1,44 @@
+//// [tests/cases/compiler/unusedImportWithSpread.ts] ////
+
+//// [a.ts]
+export default { a: 1 };
+
+//// [b1.ts]
+import a from "./a";
+
+const b1 = {} as unknown;
+({
+    // @ts-ignore
+    ...b1,
+    a
+})
+
+//// [b2.ts]
+import a from "./a";
+
+const b2 = {} as never;
+({
+    // @ts-ignore
+    ...b2,
+    a
+})
+
+
+//// [a.js]
+export default { a: 1 };
+//// [b1.js]
+import a from "./a";
+const b1 = {};
+({
+    // @ts-ignore
+    ...b1,
+    a
+});
+//// [b2.js]
+import a from "./a";
+const b2 = {};
+({
+    // @ts-ignore
+    ...b2,
+    a
+});

tests/baselines/reference/unusedImportWithSpread.symbols

@@ -0,0 +1,38 @@
+=== tests/cases/compiler/a.ts ===
+export default { a: 1 };
+>a : Symbol(a, Decl(a.ts, 0, 16))
+
+=== tests/cases/compiler/b1.ts ===
+import a from "./a";
+>a : Symbol(a, Decl(b1.ts, 0, 6))
+
+const b1 = {} as unknown;
+>b1 : Symbol(b1, Decl(b1.ts, 2, 5))
+
+({
+    // @ts-ignore
+    ...b1,
+>b1 : Symbol(b1, Decl(b1.ts, 2, 5))
+
+    a
+>a : Symbol(a, Decl(b1.ts, 5, 10))
+
+})
+
+=== tests/cases/compiler/b2.ts ===
+import a from "./a";
+>a : Symbol(a, Decl(b2.ts, 0, 6))
+
+const b2 = {} as never;
+>b2 : Symbol(b2, Decl(b2.ts, 2, 5))
+
+({
+    // @ts-ignore
+    ...b2,
+>b2 : Symbol(b2, Decl(b2.ts, 2, 5))
+
+    a
+>a : Symbol(a, Decl(b2.ts, 5, 10))
+
+})
+

tests/baselines/reference/unusedImportWithSpread.types

@@ -0,0 +1,50 @@
+=== tests/cases/compiler/a.ts ===
+export default { a: 1 };
+>{ a: 1 } : { a: number; }
+>a : number
+>1 : 1
+
+=== tests/cases/compiler/b1.ts ===
+import a from "./a";
+>a : { a: number; }
+
+const b1 = {} as unknown;
+>b1 : unknown
+>{} as unknown : unknown
+>{} : {}
+
+({
+>({    // @ts-ignore    ...b1,    a}) : error
+>{    // @ts-ignore    ...b1,    a} : error
+
+    // @ts-ignore
+    ...b1,
+>b1 : unknown
+
+    a
+>a : { a: number; }
+
+})
+
+=== tests/cases/compiler/b2.ts ===
+import a from "./a";
+>a : { a: number; }
+
+const b2 = {} as never;
+>b2 : never
+>{} as never : never
+>{} : {}
+
+({
+>({    // @ts-ignore    ...b2,    a}) : error
+>{    // @ts-ignore    ...b2,    a} : error
+
+    // @ts-ignore
+    ...b2,
+>b2 : never
+
+    a
+>a : { a: number; }
+
+})
+

tests/cases/compiler/unusedImportWithSpread.ts

@@ -0,0 +1,24 @@
+// @target: esnext
+
+// @filename: a.ts
+export default { a: 1 };
+
+// @filename: b1.ts
+import a from "./a";
+
+const b1 = {} as unknown;
+({
+    // @ts-ignore
+    ...b1,
+    a
+})
+
+// @filename: b2.ts
+import a from "./a";
+
+const b2 = {} as never;
+({
+    // @ts-ignore
+    ...b2,
+    a
+})