From 33f362abafbd68603d55756a84aaca828c368f87 Mon Sep 17 00:00:00 2001
From: Andrew Branch <andrewbranch@users.noreply.github.com>
Date: Thu, 1 Aug 2019 11:24:04 -0700
Subject: [PATCH] =?UTF-8?q?Don=E2=80=99t=20issue=20used-before-initializat?=
 =?UTF-8?q?ion=20errors=20in=20declaration=20files=20(#32579)?=
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---
 src/compiler/checker.ts                       |  2 +-
 ...BeforeDefinitionInDeclarationFiles.symbols | 26 +++++++++++++++++++
 ...seBeforeDefinitionInDeclarationFiles.types | 26 +++++++++++++++++++
 .../useBeforeDefinitionInDeclarationFiles.ts  | 10 +++++++
 4 files changed, 63 insertions(+), 1 deletion(-)
 create mode 100644 tests/baselines/reference/useBeforeDefinitionInDeclarationFiles.symbols
 create mode 100644 tests/baselines/reference/useBeforeDefinitionInDeclarationFiles.types
 create mode 100644 tests/cases/compiler/useBeforeDefinitionInDeclarationFiles.ts

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 92d026cd3dc..7d3d037b2a6 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -20700,7 +20700,7 @@ namespace ts {
 
         function checkPropertyNotUsedBeforeDeclaration(prop: Symbol, node: PropertyAccessExpression | QualifiedName, right: Identifier): void {
             const { valueDeclaration } = prop;
-            if (!valueDeclaration) {
+            if (!valueDeclaration || getSourceFileOfNode(node).isDeclarationFile) {
                 return;
             }
 
diff --git a/tests/baselines/reference/useBeforeDefinitionInDeclarationFiles.symbols b/tests/baselines/reference/useBeforeDefinitionInDeclarationFiles.symbols
new file mode 100644
index 00000000000..aafa653cf6a
--- /dev/null
+++ b/tests/baselines/reference/useBeforeDefinitionInDeclarationFiles.symbols
@@ -0,0 +1,26 @@
+=== tests/cases/compiler/declaration.d.ts ===
+export declare class ClassWithSymbols {
+>ClassWithSymbols : Symbol(ClassWithSymbols, Decl(declaration.d.ts, 0, 0))
+
+  public readonly [Namespace.locallyExportedCustomSymbol]: string;
+>[Namespace.locallyExportedCustomSymbol] : Symbol(ClassWithSymbols[Namespace.locallyExportedCustomSymbol], Decl(declaration.d.ts, 0, 39))
+>Namespace.locallyExportedCustomSymbol : Symbol(Namespace.locallyExportedCustomSymbol, Decl(declaration.d.ts, 5, 14))
+>Namespace : Symbol(Namespace, Decl(declaration.d.ts, 3, 1))
+>locallyExportedCustomSymbol : Symbol(Namespace.locallyExportedCustomSymbol, Decl(declaration.d.ts, 5, 14))
+
+  public [Namespace.fullyExportedCustomSymbol](): void;
+>[Namespace.fullyExportedCustomSymbol] : Symbol(ClassWithSymbols[Namespace.fullyExportedCustomSymbol], Decl(declaration.d.ts, 1, 66))
+>Namespace.fullyExportedCustomSymbol : Symbol(Namespace.fullyExportedCustomSymbol, Decl(declaration.d.ts, 6, 14))
+>Namespace : Symbol(Namespace, Decl(declaration.d.ts, 3, 1))
+>fullyExportedCustomSymbol : Symbol(Namespace.fullyExportedCustomSymbol, Decl(declaration.d.ts, 6, 14))
+}
+export namespace Namespace {
+>Namespace : Symbol(Namespace, Decl(declaration.d.ts, 3, 1))
+
+  export const locallyExportedCustomSymbol: unique symbol;
+>locallyExportedCustomSymbol : Symbol(locallyExportedCustomSymbol, Decl(declaration.d.ts, 5, 14))
+
+  export const fullyExportedCustomSymbol: unique symbol;
+>fullyExportedCustomSymbol : Symbol(fullyExportedCustomSymbol, Decl(declaration.d.ts, 6, 14))
+}
+
diff --git a/tests/baselines/reference/useBeforeDefinitionInDeclarationFiles.types b/tests/baselines/reference/useBeforeDefinitionInDeclarationFiles.types
new file mode 100644
index 00000000000..34c79c36bfc
--- /dev/null
+++ b/tests/baselines/reference/useBeforeDefinitionInDeclarationFiles.types
@@ -0,0 +1,26 @@
+=== tests/cases/compiler/declaration.d.ts ===
+export declare class ClassWithSymbols {
+>ClassWithSymbols : ClassWithSymbols
+
+  public readonly [Namespace.locallyExportedCustomSymbol]: string;
+>[Namespace.locallyExportedCustomSymbol] : string
+>Namespace.locallyExportedCustomSymbol : unique symbol
+>Namespace : typeof Namespace
+>locallyExportedCustomSymbol : unique symbol
+
+  public [Namespace.fullyExportedCustomSymbol](): void;
+>[Namespace.fullyExportedCustomSymbol] : () => void
+>Namespace.fullyExportedCustomSymbol : unique symbol
+>Namespace : typeof Namespace
+>fullyExportedCustomSymbol : unique symbol
+}
+export namespace Namespace {
+>Namespace : typeof Namespace
+
+  export const locallyExportedCustomSymbol: unique symbol;
+>locallyExportedCustomSymbol : unique symbol
+
+  export const fullyExportedCustomSymbol: unique symbol;
+>fullyExportedCustomSymbol : unique symbol
+}
+
diff --git a/tests/cases/compiler/useBeforeDefinitionInDeclarationFiles.ts b/tests/cases/compiler/useBeforeDefinitionInDeclarationFiles.ts
new file mode 100644
index 00000000000..e4ebb083830
--- /dev/null
+++ b/tests/cases/compiler/useBeforeDefinitionInDeclarationFiles.ts
@@ -0,0 +1,10 @@
+// @filename: declaration.d.ts
+
+export declare class ClassWithSymbols {
+  public readonly [Namespace.locallyExportedCustomSymbol]: string;
+  public [Namespace.fullyExportedCustomSymbol](): void;
+}
+export namespace Namespace {
+  export const locallyExportedCustomSymbol: unique symbol;
+  export const fullyExportedCustomSymbol: unique symbol;
+}