Fix visitLexicalEnvironment to properly merge hoisted declarations (#33219)

Author: rbuckton

src/compiler/visitor.ts

@@ -141,11 +141,8 @@ namespace ts {
     export function visitLexicalEnvironment(statements: NodeArray<Statement>, visitor: Visitor, context: TransformationContext, start?: number, ensureUseStrict?: boolean) {
         context.startLexicalEnvironment();
         statements = visitNodes(statements, visitor, isStatement, start);
-        if (ensureUseStrict && !startsWithUseStrict(statements)) {
-            statements = setTextRange(createNodeArray([createExpressionStatement(createLiteral("use strict")), ...statements]), statements);
-        }
-        const declarations = context.endLexicalEnvironment();
-        return setTextRange(createNodeArray(concatenate(declarations, statements)), statements);
+        if (ensureUseStrict) statements = ts.ensureUseStrict(statements); // tslint:disable-line no-unnecessary-qualifier
+        return mergeLexicalEnvironment(statements, context.endLexicalEnvironment());
     }
 
     /**

tests/baselines/reference/instanceMemberWithComputedPropertyName.js

@@ -1,5 +1,6 @@
 //// [instanceMemberWithComputedPropertyName.ts]
 // https://github.com/microsoft/TypeScript/issues/30953
+"use strict";
 const x = 1;
 class C {
     [x] = true;
@@ -9,8 +10,9 @@ class C {
 }
 
 //// [instanceMemberWithComputedPropertyName.js]
-var _a;
 // https://github.com/microsoft/TypeScript/issues/30953
+"use strict";
+var _a;
 var x = 1;
 var C = /** @class */ (function () {
     function C() {

tests/baselines/reference/instanceMemberWithComputedPropertyName.symbols

@@ -1,20 +1,21 @@
 === tests/cases/conformance/classes/propertyMemberDeclarations/instanceMemberWithComputedPropertyName.ts ===
 // https://github.com/microsoft/TypeScript/issues/30953
+"use strict";
 const x = 1;
->x : Symbol(x, Decl(instanceMemberWithComputedPropertyName.ts, 1, 5))
+>x : Symbol(x, Decl(instanceMemberWithComputedPropertyName.ts, 2, 5))
 
 class C {
->C : Symbol(C, Decl(instanceMemberWithComputedPropertyName.ts, 1, 12))
+>C : Symbol(C, Decl(instanceMemberWithComputedPropertyName.ts, 2, 12))
 
     [x] = true;
->[x] : Symbol(C[x], Decl(instanceMemberWithComputedPropertyName.ts, 2, 9))
->x : Symbol(x, Decl(instanceMemberWithComputedPropertyName.ts, 1, 5))
+>[x] : Symbol(C[x], Decl(instanceMemberWithComputedPropertyName.ts, 3, 9))
+>x : Symbol(x, Decl(instanceMemberWithComputedPropertyName.ts, 2, 5))
 
     constructor() {
         const { a, b } = { a: 1, b: 2 };
->a : Symbol(a, Decl(instanceMemberWithComputedPropertyName.ts, 5, 15))
->b : Symbol(b, Decl(instanceMemberWithComputedPropertyName.ts, 5, 18))
->a : Symbol(a, Decl(instanceMemberWithComputedPropertyName.ts, 5, 26))
->b : Symbol(b, Decl(instanceMemberWithComputedPropertyName.ts, 5, 32))
+>a : Symbol(a, Decl(instanceMemberWithComputedPropertyName.ts, 6, 15))
+>b : Symbol(b, Decl(instanceMemberWithComputedPropertyName.ts, 6, 18))
+>a : Symbol(a, Decl(instanceMemberWithComputedPropertyName.ts, 6, 26))
+>b : Symbol(b, Decl(instanceMemberWithComputedPropertyName.ts, 6, 32))
     }
 }

tests/baselines/reference/instanceMemberWithComputedPropertyName.types

@@ -1,5 +1,8 @@
 === tests/cases/conformance/classes/propertyMemberDeclarations/instanceMemberWithComputedPropertyName.ts ===
 // https://github.com/microsoft/TypeScript/issues/30953
+"use strict";
+>"use strict" : "use strict"
+
 const x = 1;
 >x : 1
 >1 : 1

tests/cases/conformance/classes/propertyMemberDeclarations/instanceMemberWithComputedPropertyName.ts

@@ -1,4 +1,5 @@
 // https://github.com/microsoft/TypeScript/issues/30953
+"use strict";
 const x = 1;
 class C {
     [x] = true;