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Check return code paths on getters #10102

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Merged
merged 2 commits into from
Aug 19, 2016
Merged

Check return code paths on getters #10102

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8941951
Check return paths on getters
weswigham Aug 2, 2016
720cf54
Remove TODO comment
weswigham Aug 17, 2016
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12 changes: 5 additions & 7 deletions src/compiler/checker.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -13918,12 +13918,7 @@ namespace ts {
checkSignatureDeclaration(node);
if (node.kind === SyntaxKind.GetAccessor) {
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Does this imply there's more work to do?

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Mmmm... Maybe. I wanted a second opinion on that. The remaining code below
is getter-specific, so I'm unsure of weather or not it should be merged
into checkAllCodePathsInNonVoidFunction.

On Mon, Aug 8, 2016, 11:01 AM Anders Hejlsberg [email protected]
wrote:

In src/compiler/checker.ts
#10102 (comment):

@@ -13916,14 +13916,10 @@ namespace ts {

             checkDecorators(node);
             checkSignatureDeclaration(node);

  •            // TODO (weswig): Consolidate the below into checkAllCodePathsInNonVoidFunctionReturnOrThrow

Does this imply there's more work to do?

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Looks like the remaining code is just cherry picking the case where the accessor has an implicit return and no explicit returns. Not sure why that case needs special treatmeant if it is already handled in the checkAllCodePathsEtcEtc function. What happens to the baselines if you remove it?

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The checkAllCodePathsInNonVoidFunction actually doesn't handle that case, because for a normal function it is allowed. Removing the below block literally just removes that error (that a get accessor must contain an explicit return value) from every baseline.

if (!isInAmbientContext(node) && nodeIsPresent(node.body) && (node.flags & NodeFlags.HasImplicitReturn)) {
if (node.flags & NodeFlags.HasExplicitReturn) {
if (compilerOptions.noImplicitReturns) {
error(node.name, Diagnostics.Not_all_code_paths_return_a_value);
}
}
else {
if (!(node.flags & NodeFlags.HasExplicitReturn)) {
error(node.name, Diagnostics.A_get_accessor_must_return_a_value);
}
}
Expand Down Expand Up @@ -13953,7 +13948,10 @@ namespace ts {
checkAccessorDeclarationTypesIdentical(node, otherAccessor, getThisTypeOfDeclaration, Diagnostics.get_and_set_accessor_must_have_the_same_this_type);
}
}
getTypeOfAccessors(getSymbolOfNode(node));
const returnType = getTypeOfAccessors(getSymbolOfNode(node));
if (node.kind === SyntaxKind.GetAccessor) {
checkAllCodePathsInNonVoidFunctionReturnOrThrow(node, returnType);
}
}
if (node.parent.kind !== SyntaxKind.ObjectLiteralExpression) {
checkSourceElement(node.body);
Expand Down
27 changes: 27 additions & 0 deletions tests/baselines/reference/getterControlFlowStrictNull.errors.txt
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Original file line number Diff line number Diff line change
@@ -0,0 +1,27 @@
tests/cases/compiler/getterControlFlowStrictNull.ts(2,9): error TS2366: Function lacks ending return statement and return type does not include 'undefined'.
tests/cases/compiler/getterControlFlowStrictNull.ts(11,14): error TS2366: Function lacks ending return statement and return type does not include 'undefined'.


==== tests/cases/compiler/getterControlFlowStrictNull.ts (2 errors) ====
class A {
a(): string | null {
~~~~~~~~~~~~~
!!! error TS2366: Function lacks ending return statement and return type does not include 'undefined'.
if (Math.random() > 0.5) {
return '';
}

// it does error here as expected
}
}
class B {
get a(): string | null {
~~~~~~~~~~~~~
!!! error TS2366: Function lacks ending return statement and return type does not include 'undefined'.
if (Math.random() > 0.5) {
return '';
}

// it should error here because it returns undefined
}
}
47 changes: 47 additions & 0 deletions tests/baselines/reference/getterControlFlowStrictNull.js
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@@ -0,0 +1,47 @@
//// [getterControlFlowStrictNull.ts]
class A {
a(): string | null {
if (Math.random() > 0.5) {
return '';
}

// it does error here as expected
}
}
class B {
get a(): string | null {
if (Math.random() > 0.5) {
return '';
}

// it should error here because it returns undefined
}
}

//// [getterControlFlowStrictNull.js]
var A = (function () {
function A() {
}
A.prototype.a = function () {
if (Math.random() > 0.5) {
return '';
}
// it does error here as expected
};
return A;
}());
var B = (function () {
function B() {
}
Object.defineProperty(B.prototype, "a", {
get: function () {
if (Math.random() > 0.5) {
return '';
}
// it should error here because it returns undefined
},
enumerable: true,
configurable: true
});
return B;
}());
20 changes: 20 additions & 0 deletions tests/cases/compiler/getterControlFlowStrictNull.ts
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@@ -0,0 +1,20 @@
//@strictNullChecks: true
//@target: ES5
class A {
a(): string | null {
if (Math.random() > 0.5) {
return '';
}

// it does error here as expected
}
}
class B {
get a(): string | null {
if (Math.random() > 0.5) {
return '';
}

// it should error here because it returns undefined
}
}