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Merge pull request #12694 from Microsoft/destructuring-initialisers-can-reference-previous-elements

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Binding element initialisers can reference previous elements
This commit is contained in:
Nathan Shively-Sanders 2016-12-21 16:29:44 -08:00 committed by GitHub
commit e8b3ff0a1a
7 changed files with 138 additions and 5 deletions
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34
src/compiler/checker.ts
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@ -636,11 +636,24 @@ namespace ts {
if (declaration.pos <= usage.pos) {
// declaration is before usage
// still might be illegal if usage is in the initializer of the variable declaration
return declaration.kind !== SyntaxKind.VariableDeclaration ||
!isImmediatelyUsedInInitializerOfBlockScopedVariable(<VariableDeclaration>declaration, usage);
if (declaration.kind === SyntaxKind.BindingElement) {
// still might be illegal if declaration and usage are both binding elements (eg var [a = b, b = b] = [1, 2])
const errorBindingElement = getAncestor(usage, SyntaxKind.BindingElement) as BindingElement;
if (errorBindingElement) {
return getAncestorBindingPattern(errorBindingElement) !== getAncestorBindingPattern(declaration) ||
declaration.pos < errorBindingElement.pos;
}
// or it might be illegal if usage happens before parent variable is declared (eg var [a] = a)
return isBlockScopedNameDeclaredBeforeUse(getAncestor(declaration, SyntaxKind.VariableDeclaration) as Declaration, usage);
}
else if (declaration.kind === SyntaxKind.VariableDeclaration) {
// still might be illegal if usage is in the initializer of the variable declaration (eg var a = a)
return !isImmediatelyUsedInInitializerOfBlockScopedVariable(declaration as VariableDeclaration, usage);
}
return true;
}
// declaration is after usage
// can be legal if usage is deferred (i.e. inside function or in initializer of instance property)
const container = getEnclosingBlockScopeContainer(declaration);
@ -697,6 +710,16 @@ namespace ts {
}
return false;
}
function getAncestorBindingPattern(node: Node): BindingPattern {
while (node) {
if (isBindingPattern(node)) {
return node;
}
node = node.parent;
}
return undefined;
}
}
// Resolve a given name for a given meaning at a given location. An error is reported if the name was not found and
@ -1063,7 +1086,7 @@ namespace ts {
Debug.assert(declaration !== undefined, "Block-scoped variable declaration is undefined");
if (!isInAmbientContext(declaration) && !isBlockScopedNameDeclaredBeforeUse(<Declaration>getAncestor(declaration, SyntaxKind.VariableDeclaration), errorLocation)) {
if (!isInAmbientContext(declaration) && !isBlockScopedNameDeclaredBeforeUse(declaration, errorLocation)) {
error(errorLocation, Diagnostics.Block_scoped_variable_0_used_before_its_declaration, declarationNameToString(declaration.name));
}
}
@ -17157,7 +17180,8 @@ namespace ts {
// so we need to do a bit of extra work to check if reference is legal
const enclosingContainer = getEnclosingBlockScopeContainer(symbol.valueDeclaration);
if (enclosingContainer === func) {
if (symbol.valueDeclaration.kind === SyntaxKind.Parameter) {
if (symbol.valueDeclaration.kind === SyntaxKind.Parameter ||
symbol.valueDeclaration.kind === SyntaxKind.BindingElement) {
// it is ok to reference parameter in initializer if either
// - parameter is located strictly on the left of current parameter declaration
if (symbol.valueDeclaration.pos < node.pos) {

26
tests/baselines/reference/destructuringArrayBindingPatternAndAssignment3.errors.txt Normal file
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@ -0,0 +1,26 @@
tests/cases/conformance/es6/destructuring/destructuringArrayBindingPatternAndAssignment3.ts(2,22): error TS2448: Block-scoped variable 'e' used before its declaration.
tests/cases/conformance/es6/destructuring/destructuringArrayBindingPatternAndAssignment3.ts(3,22): error TS2448: Block-scoped variable 'i' used before its declaration.
tests/cases/conformance/es6/destructuring/destructuringArrayBindingPatternAndAssignment3.ts(7,27): error TS2372: Parameter 'e' cannot be referenced in its initializer.
tests/cases/conformance/es6/destructuring/destructuringArrayBindingPatternAndAssignment3.ts(9,27): error TS2373: Initializer of parameter 'h' cannot reference identifier 'i' declared after it.
==== tests/cases/conformance/es6/destructuring/destructuringArrayBindingPatternAndAssignment3.ts (4 errors) ====
const [a, b = a] = [1]; // ok
const [c, d = c, e = e] = [1]; // error for e = e
~
!!! error TS2448: Block-scoped variable 'e' used before its declaration.
const [f, g = f, h = i, i = f] = [1]; // error for h = i
~
!!! error TS2448: Block-scoped variable 'i' used before its declaration.
(function ([a, b = a]) { // ok
})([1]);
(function ([c, d = c, e = e]) { // error for e = e
~
!!! error TS2372: Parameter 'e' cannot be referenced in its initializer.
})([1]);
(function ([f, g = f, h = i, i = f]) { // error for h = i
~
!!! error TS2373: Initializer of parameter 'h' cannot reference identifier 'i' declared after it.
})([1])

26
tests/baselines/reference/destructuringArrayBindingPatternAndAssignment3.js Normal file
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@ -0,0 +1,26 @@
//// [destructuringArrayBindingPatternAndAssignment3.ts]
const [a, b = a] = [1]; // ok
const [c, d = c, e = e] = [1]; // error for e = e
const [f, g = f, h = i, i = f] = [1]; // error for h = i
(function ([a, b = a]) { // ok
})([1]);
(function ([c, d = c, e = e]) { // error for e = e
})([1]);
(function ([f, g = f, h = i, i = f]) { // error for h = i
})([1])
//// [destructuringArrayBindingPatternAndAssignment3.js]
var _a = [1], a = _a[0], _b = _a[1], b = _b === void 0 ? a : _b; // ok
var _c = [1], c = _c[0], _d = _c[1], d = _d === void 0 ? c : _d, _e = _c[2], e = _e === void 0 ? e : _e; // error for e = e
var _f = [1], f = _f[0], _g = _f[1], g = _g === void 0 ? f : _g, _h = _f[2], h = _h === void 0 ? i : _h, _j = _f[3], i = _j === void 0 ? f : _j; // error for h = i
(function (_a) {
var a = _a[0], _b = _a[1], b = _b === void 0 ? a : _b;
})([1]);
(function (_a) {
var c = _a[0], _b = _a[1], d = _b === void 0 ? c : _b, _c = _a[2], e = _c === void 0 ? e : _c;
})([1]);
(function (_a) {
var f = _a[0], _b = _a[1], g = _b === void 0 ? f : _b, _c = _a[2], h = _c === void 0 ? i : _c, _d = _a[3], i = _d === void 0 ? f : _d;
})([1]);

18
tests/baselines/reference/destructuringObjectBindingPatternAndAssignment4.errors.txt Normal file
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@ -0,0 +1,18 @@
tests/cases/conformance/es6/destructuring/destructuringObjectBindingPatternAndAssignment4.ts(6,9): error TS2448: Block-scoped variable 'f' used before its declaration.
tests/cases/conformance/es6/destructuring/destructuringObjectBindingPatternAndAssignment4.ts(7,9): error TS2448: Block-scoped variable 'f' used before its declaration.
==== tests/cases/conformance/es6/destructuring/destructuringObjectBindingPatternAndAssignment4.ts (2 errors) ====
const {
a = 1,
b = 2,
c = b, // ok
d = a, // ok
e = f, // error
~
!!! error TS2448: Block-scoped variable 'f' used before its declaration.
f = f // error
~
!!! error TS2448: Block-scoped variable 'f' used before its declaration.
} = { } as any;

21
tests/baselines/reference/destructuringObjectBindingPatternAndAssignment4.js Normal file
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@ -0,0 +1,21 @@
//// [destructuringObjectBindingPatternAndAssignment4.ts]
const {
a = 1,
b = 2,
c = b, // ok
d = a, // ok
e = f, // error
f = f // error
} = { } as any;
//// [destructuringObjectBindingPatternAndAssignment4.js]
var _a = {}, _b = _a.a, a = _b === void 0 ? 1 : _b, _c = _a.b, b = _c === void 0 ? 2 : _c, _d = _a.c, c = _d === void 0 ? b : _d, // ok
_e = _a.d, // ok
d = _e === void 0 ? a : _e, // ok
_f = _a.e, // ok
e = _f === void 0 ? f : _f, // error
_g = _a.f // error
, // error
f = _g === void 0 ? f : _g // error
;

10
tests/cases/conformance/es6/destructuring/destructuringArrayBindingPatternAndAssignment3.ts Normal file
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@ -0,0 +1,10 @@
const [a, b = a] = [1]; // ok
const [c, d = c, e = e] = [1]; // error for e = e
const [f, g = f, h = i, i = f] = [1]; // error for h = i
(function ([a, b = a]) { // ok
})([1]);
(function ([c, d = c, e = e]) { // error for e = e
})([1]);
(function ([f, g = f, h = i, i = f]) { // error for h = i
})([1])

8
tests/cases/conformance/es6/destructuring/destructuringObjectBindingPatternAndAssignment4.ts Normal file
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@ -0,0 +1,8 @@
const {
a = 1,
b = 2,
c = b, // ok
d = a, // ok
e = f, // error
f = f // error
} = { } as any;