From 1518cd98f4096d0e35c8af61d31ce87045babb88 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mateusz=20Burzy=C5=84ski?= <mateuszburzynski@gmail.com>
Date: Wed, 24 May 2023 19:19:01 +0200
Subject: [PATCH] Fixed declaration emit for undefined properties inferred from
 functions in other array elements (#53938)

---
 src/compiler/checker.ts                       | 49 ++++++++++---------
 ...nferredUndefinedPropFromFunctionInArray.js | 23 +++++++++
 ...edUndefinedPropFromFunctionInArray.symbols |  9 ++++
 ...rredUndefinedPropFromFunctionInArray.types | 14 ++++++
 ...nferredUndefinedPropFromFunctionInArray.ts |  5 ++
 5 files changed, 76 insertions(+), 24 deletions(-)
 create mode 100644 tests/baselines/reference/declarationEmitInferredUndefinedPropFromFunctionInArray.js
 create mode 100644 tests/baselines/reference/declarationEmitInferredUndefinedPropFromFunctionInArray.symbols
 create mode 100644 tests/baselines/reference/declarationEmitInferredUndefinedPropFromFunctionInArray.types
 create mode 100644 tests/cases/compiler/declarationEmitInferredUndefinedPropFromFunctionInArray.ts

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 547d5fdafd3..6a95bd7b9b4 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -7126,36 +7126,37 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
                     const methodDeclaration = signatureToSignatureDeclarationHelper(signature, SyntaxKind.MethodSignature, context, { name: propertyName, questionToken: optionalToken }) as MethodSignature;
                     typeElements.push(preserveCommentsOn(methodDeclaration));
                 }
+                if (signatures.length || !optionalToken) {
+                    return;
+                }
+            }
+            let propertyTypeNode: TypeNode;
+            if (shouldUsePlaceholderForProperty(propertySymbol, context)) {
+                propertyTypeNode = createElidedInformationPlaceholder(context);
             }
             else {
-                let propertyTypeNode: TypeNode;
-                if (shouldUsePlaceholderForProperty(propertySymbol, context)) {
-                    propertyTypeNode = createElidedInformationPlaceholder(context);
+                if (propertyIsReverseMapped) {
+                    context.reverseMappedStack ||= [];
+                    context.reverseMappedStack.push(propertySymbol as ReverseMappedSymbol);
                 }
-                else {
-                    if (propertyIsReverseMapped) {
-                        context.reverseMappedStack ||= [];
-                        context.reverseMappedStack.push(propertySymbol as ReverseMappedSymbol);
-                    }
-                    propertyTypeNode = propertyType ? serializeTypeForDeclaration(context, propertyType, propertySymbol, saveEnclosingDeclaration) : factory.createKeywordTypeNode(SyntaxKind.AnyKeyword);
-                    if (propertyIsReverseMapped) {
-                        context.reverseMappedStack!.pop();
-                    }
+                propertyTypeNode = propertyType ? serializeTypeForDeclaration(context, propertyType, propertySymbol, saveEnclosingDeclaration) : factory.createKeywordTypeNode(SyntaxKind.AnyKeyword);
+                if (propertyIsReverseMapped) {
+                    context.reverseMappedStack!.pop();
                 }
-
-                const modifiers = isReadonlySymbol(propertySymbol) ? [factory.createToken(SyntaxKind.ReadonlyKeyword)] : undefined;
-                if (modifiers) {
-                    context.approximateLength += 9;
-                }
-                const propertySignature = factory.createPropertySignature(
-                    modifiers,
-                    propertyName,
-                    optionalToken,
-                    propertyTypeNode);
-
-                typeElements.push(preserveCommentsOn(propertySignature));
             }
 
+            const modifiers = isReadonlySymbol(propertySymbol) ? [factory.createToken(SyntaxKind.ReadonlyKeyword)] : undefined;
+            if (modifiers) {
+                context.approximateLength += 9;
+            }
+            const propertySignature = factory.createPropertySignature(
+                modifiers,
+                propertyName,
+                optionalToken,
+                propertyTypeNode);
+
+            typeElements.push(preserveCommentsOn(propertySignature));
+
             function preserveCommentsOn<T extends Node>(node: T) {
                 if (some(propertySymbol.declarations, d => d.kind === SyntaxKind.JSDocPropertyTag)) {
                     const d = propertySymbol.declarations?.find(d => d.kind === SyntaxKind.JSDocPropertyTag)! as JSDocPropertyTag;
diff --git a/tests/baselines/reference/declarationEmitInferredUndefinedPropFromFunctionInArray.js b/tests/baselines/reference/declarationEmitInferredUndefinedPropFromFunctionInArray.js
new file mode 100644
index 00000000000..6d59e542802
--- /dev/null
+++ b/tests/baselines/reference/declarationEmitInferredUndefinedPropFromFunctionInArray.js
@@ -0,0 +1,23 @@
+//// [declarationEmitInferredUndefinedPropFromFunctionInArray.ts]
+// repro from https://github.com/microsoft/TypeScript/issues/53914
+
+export let b = [{ foo: 0, m() {} }, { bar: 1 }];
+
+//// [declarationEmitInferredUndefinedPropFromFunctionInArray.js]
+"use strict";
+// repro from https://github.com/microsoft/TypeScript/issues/53914
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.b = void 0;
+exports.b = [{ foo: 0, m: function () { } }, { bar: 1 }];
+
+
+//// [declarationEmitInferredUndefinedPropFromFunctionInArray.d.ts]
+export declare let b: ({
+    foo: number;
+    m(): void;
+    bar?: undefined;
+} | {
+    bar: number;
+    foo?: undefined;
+    m?: undefined;
+})[];
diff --git a/tests/baselines/reference/declarationEmitInferredUndefinedPropFromFunctionInArray.symbols b/tests/baselines/reference/declarationEmitInferredUndefinedPropFromFunctionInArray.symbols
new file mode 100644
index 00000000000..f1de964bf66
--- /dev/null
+++ b/tests/baselines/reference/declarationEmitInferredUndefinedPropFromFunctionInArray.symbols
@@ -0,0 +1,9 @@
+=== tests/cases/compiler/declarationEmitInferredUndefinedPropFromFunctionInArray.ts ===
+// repro from https://github.com/microsoft/TypeScript/issues/53914
+
+export let b = [{ foo: 0, m() {} }, { bar: 1 }];
+>b : Symbol(b, Decl(declarationEmitInferredUndefinedPropFromFunctionInArray.ts, 2, 10))
+>foo : Symbol(foo, Decl(declarationEmitInferredUndefinedPropFromFunctionInArray.ts, 2, 17))
+>m : Symbol(m, Decl(declarationEmitInferredUndefinedPropFromFunctionInArray.ts, 2, 25))
+>bar : Symbol(bar, Decl(declarationEmitInferredUndefinedPropFromFunctionInArray.ts, 2, 37))
+
diff --git a/tests/baselines/reference/declarationEmitInferredUndefinedPropFromFunctionInArray.types b/tests/baselines/reference/declarationEmitInferredUndefinedPropFromFunctionInArray.types
new file mode 100644
index 00000000000..ae474c22317
--- /dev/null
+++ b/tests/baselines/reference/declarationEmitInferredUndefinedPropFromFunctionInArray.types
@@ -0,0 +1,14 @@
+=== tests/cases/compiler/declarationEmitInferredUndefinedPropFromFunctionInArray.ts ===
+// repro from https://github.com/microsoft/TypeScript/issues/53914
+
+export let b = [{ foo: 0, m() {} }, { bar: 1 }];
+>b : ({ foo: number; m(): void; bar?: undefined; } | { bar: number; foo?: undefined; m?: undefined; })[]
+>[{ foo: 0, m() {} }, { bar: 1 }] : ({ foo: number; m(): void; } | { bar: number; })[]
+>{ foo: 0, m() {} } : { foo: number; m(): void; }
+>foo : number
+>0 : 0
+>m : () => void
+>{ bar: 1 } : { bar: number; }
+>bar : number
+>1 : 1
+
diff --git a/tests/cases/compiler/declarationEmitInferredUndefinedPropFromFunctionInArray.ts b/tests/cases/compiler/declarationEmitInferredUndefinedPropFromFunctionInArray.ts
new file mode 100644
index 00000000000..d12a2717ca1
--- /dev/null
+++ b/tests/cases/compiler/declarationEmitInferredUndefinedPropFromFunctionInArray.ts
@@ -0,0 +1,5 @@
+// @declaration: true
+
+// repro from https://github.com/microsoft/TypeScript/issues/53914
+
+export let b = [{ foo: 0, m() {} }, { bar: 1 }];
\ No newline at end of file