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allow BindingPattern in FunctionRestParameter
also add downlevel emit for the destructured rest param Part of microsoft#6275
1 parent 3bfe91c commit d4f6b9b

16 files changed

Lines changed: 42 additions & 125 deletions

‎src/compiler/checker.ts‎

Lines changed: 0 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -28570,10 +28570,6 @@ namespace ts {
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checkGrammarForDisallowedTrailingComma(parameters, Diagnostics.A_rest_parameter_or_binding_pattern_may_not_have_a_trailing_comma);
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}
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28573-
if (isBindingPattern(parameter.name)) {
28574-
return grammarErrorOnNode(parameter.name, Diagnostics.A_rest_element_cannot_contain_a_binding_pattern);
28575-
}
28576-
2857728573
if (parameter.questionToken) {
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return grammarErrorOnNode(parameter.questionToken, Diagnostics.A_rest_parameter_cannot_be_optional);
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}

‎src/compiler/transformers/es2015.ts‎

Lines changed: 22 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -1340,8 +1340,8 @@ namespace ts {
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* part of a constructor declaration with a
13411341
* synthesized call to `super`
13421342
*/
1343-
function shouldAddRestParameter(node: ParameterDeclaration | undefined, inConstructorWithSynthesizedSuper: boolean) {
1344-
return node && node.dotDotDotToken && node.name.kind === SyntaxKind.Identifier && !inConstructorWithSynthesizedSuper;
1343+
function shouldAddRestParameter(node: ParameterDeclaration | undefined, inConstructorWithSynthesizedSuper: boolean): node is ParameterDeclaration {
1344+
return !!(node && node.dotDotDotToken && !inConstructorWithSynthesizedSuper);
13451345
}
13461346

13471347
/**
@@ -1360,11 +1360,11 @@ namespace ts {
13601360
}
13611361

13621362
// `declarationName` is the name of the local declaration for the parameter.
1363-
const declarationName = getMutableClone(<Identifier>parameter!.name);
1363+
const declarationName = parameter.name.kind === SyntaxKind.Identifier ? getMutableClone(parameter.name) : createTempVariable(/*recordTempVariable*/ undefined);
13641364
setEmitFlags(declarationName, EmitFlags.NoSourceMap);
13651365

13661366
// `expressionName` is the name of the parameter used in expressions.
1367-
const expressionName = getSynthesizedClone(<Identifier>parameter!.name);
1367+
const expressionName = parameter.name.kind === SyntaxKind.Identifier ? getSynthesizedClone(parameter.name) : declarationName;
13681368
const restIndex = node.parameters.length - 1;
13691369
const temp = createLoopVariable();
13701370

@@ -1429,6 +1429,24 @@ namespace ts {
14291429
setEmitFlags(forStatement, EmitFlags.CustomPrologue);
14301430
startOnNewLine(forStatement);
14311431
statements.push(forStatement);
1432+
1433+
if (parameter.name.kind !== SyntaxKind.Identifier) {
1434+
// do the actual destructuring of the rest parameter if necessary
1435+
statements.push(
1436+
setEmitFlags(
1437+
setTextRange(
1438+
createVariableStatement(
1439+
/*modifiers*/ undefined,
1440+
createVariableDeclarationList(
1441+
flattenDestructuringBinding(parameter, visitor, context, FlattenLevel.All, expressionName),
1442+
)
1443+
),
1444+
parameter
1445+
),
1446+
EmitFlags.CustomPrologue
1447+
)
1448+
);
1449+
}
14321450
}
14331451

14341452
/**

‎tests/baselines/reference/iterableArrayPattern14.errors.txt‎

Lines changed: 0 additions & 23 deletions
This file was deleted.

‎tests/baselines/reference/iterableArrayPattern15.errors.txt‎

Lines changed: 0 additions & 23 deletions
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‎tests/baselines/reference/iterableArrayPattern16.errors.txt‎

Lines changed: 1 addition & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -1,13 +1,10 @@
1-
tests/cases/conformance/es6/destructuring/iterableArrayPattern16.ts(1,17): error TS2501: A rest element cannot contain a binding pattern.
21
tests/cases/conformance/es6/destructuring/iterableArrayPattern16.ts(2,5): error TS2345: Argument of type 'FooIterator' is not assignable to parameter of type '[Bar, Bar]'.
32
Property '0' is missing in type 'FooIterator'.
43
tests/cases/conformance/es6/destructuring/iterableArrayPattern16.ts(2,12): error TS2449: Class 'FooIteratorIterator' used before its declaration.
54

65

7-
==== tests/cases/conformance/es6/destructuring/iterableArrayPattern16.ts (3 errors) ====
6+
==== tests/cases/conformance/es6/destructuring/iterableArrayPattern16.ts (2 errors) ====
87
function fun(...[a, b]: [Bar, Bar][]) { }
9-
~~~~~~
10-
!!! error TS2501: A rest element cannot contain a binding pattern.
118
fun(...new FooIteratorIterator);
129
~~~~~~~~~~~~~~~~~~~~~~~~~~
1310
!!! error TS2345: Argument of type 'FooIterator' is not assignable to parameter of type '[Bar, Bar]'.

‎tests/baselines/reference/iterableArrayPattern17.errors.txt‎

Lines changed: 1 addition & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -1,9 +1,8 @@
1-
tests/cases/conformance/es6/destructuring/iterableArrayPattern17.ts(16,17): error TS2501: A rest element cannot contain a binding pattern.
21
tests/cases/conformance/es6/destructuring/iterableArrayPattern17.ts(17,5): error TS2345: Argument of type 'FooIterator' is not assignable to parameter of type 'Bar'.
32
Property 'x' is missing in type 'FooIterator'.
43

54

6-
==== tests/cases/conformance/es6/destructuring/iterableArrayPattern17.ts (2 errors) ====
5+
==== tests/cases/conformance/es6/destructuring/iterableArrayPattern17.ts (1 errors) ====
76
class Bar { x }
87
class Foo extends Bar { y }
98
class FooIterator {
@@ -20,8 +19,6 @@ tests/cases/conformance/es6/destructuring/iterableArrayPattern17.ts(17,5): error
2019
}
2120

2221
function fun(...[a, b]: Bar[]) { }
23-
~~~~~~
24-
!!! error TS2501: A rest element cannot contain a binding pattern.
2522
fun(new FooIterator);
2623
~~~~~~~~~~~~~~~
2724
!!! error TS2345: Argument of type 'FooIterator' is not assignable to parameter of type 'Bar'.

‎tests/baselines/reference/iterableArrayPattern20.errors.txt‎

Lines changed: 0 additions & 23 deletions
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‎tests/baselines/reference/iterableArrayPattern25.errors.txt‎

Lines changed: 1 addition & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -1,11 +1,8 @@
1-
tests/cases/conformance/es6/destructuring/iterableArrayPattern25.ts(1,33): error TS2501: A rest element cannot contain a binding pattern.
21
tests/cases/conformance/es6/destructuring/iterableArrayPattern25.ts(2,1): error TS2554: Expected 2 arguments, but got 1.
32

43

5-
==== tests/cases/conformance/es6/destructuring/iterableArrayPattern25.ts (2 errors) ====
4+
==== tests/cases/conformance/es6/destructuring/iterableArrayPattern25.ts (1 errors) ====
65
function takeFirstTwoEntries(...[[k1, v1], [k2, v2]]) { }
7-
~~~~~~~~~~~~~~~~~~~~
8-
!!! error TS2501: A rest element cannot contain a binding pattern.
96
takeFirstTwoEntries(new Map([["", 0], ["hello", 1]]));
107
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
118
!!! error TS2554: Expected 2 arguments, but got 1.

‎tests/baselines/reference/iterableArrayPattern26.errors.txt‎

Lines changed: 1 addition & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -1,12 +1,9 @@
1-
tests/cases/conformance/es6/destructuring/iterableArrayPattern26.ts(1,33): error TS2501: A rest element cannot contain a binding pattern.
21
tests/cases/conformance/es6/destructuring/iterableArrayPattern26.ts(2,21): error TS2345: Argument of type 'Map<string, number>' is not assignable to parameter of type '[string, number]'.
32
Property '0' is missing in type 'Map<string, number>'.
43

54

6-
==== tests/cases/conformance/es6/destructuring/iterableArrayPattern26.ts (2 errors) ====
5+
==== tests/cases/conformance/es6/destructuring/iterableArrayPattern26.ts (1 errors) ====
76
function takeFirstTwoEntries(...[[k1, v1], [k2, v2]]: [string, number][]) { }
8-
~~~~~~~~~~~~~~~~~~~~
9-
!!! error TS2501: A rest element cannot contain a binding pattern.
107
takeFirstTwoEntries(new Map([["", 0], ["hello", 1]]));
118
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
129
!!! error TS2345: Argument of type 'Map<string, number>' is not assignable to parameter of type '[string, number]'.

‎tests/baselines/reference/iterableArrayPattern27.errors.txt‎

Lines changed: 0 additions & 8 deletions
This file was deleted.

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