From b0e4ff6f210ad767067bdbc2f2f418e206bed282 Mon Sep 17 00:00:00 2001
From: Ryan Cavanaugh <RyanCavanaugh@users.noreply.github.com>
Date: Mon, 26 Aug 2024 12:30:27 -0700
Subject: [PATCH] `this` can be nullish (#59761)
---
src/compiler/checker.ts | 1 +
.../reference/predicateSemantics.errors.txt | 6 +++++-
tests/baselines/reference/predicateSemantics.js | 10 +++++++++-
.../reference/predicateSemantics.symbols | 9 +++++++++
.../baselines/reference/predicateSemantics.types | 15 +++++++++++++++
tests/cases/compiler/predicateSemantics.ts | 5 +++++
6 files changed, 44 insertions(+), 2 deletions(-)
diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 91346429b1774..e3350d48bdf7a 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -39725,6 +39725,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
case SyntaxKind.NewExpression:
case SyntaxKind.PropertyAccessExpression:
case SyntaxKind.YieldExpression:
+ case SyntaxKind.ThisKeyword:
return PredicateSemantics.Sometimes;
case SyntaxKind.BinaryExpression:
// List of operators that can produce null/undefined:
diff --git a/tests/baselines/reference/predicateSemantics.errors.txt b/tests/baselines/reference/predicateSemantics.errors.txt
index 883ce4570983b..14251121358c4 100644
--- a/tests/baselines/reference/predicateSemantics.errors.txt
+++ b/tests/baselines/reference/predicateSemantics.errors.txt
@@ -73,4 +73,8 @@ predicateSemantics.ts(36,8): error TS2872: This kind of expression is always tru
// Should be OK
console.log((cond || undefined) && 1 / cond);
-
\ No newline at end of file
+
+ function foo(this: Object | undefined) {
+ // Should be OK
+ return this ?? 0;
+ }
\ No newline at end of file
diff --git a/tests/baselines/reference/predicateSemantics.js b/tests/baselines/reference/predicateSemantics.js
index 4ed294189332c..eb0b66516b62c 100644
--- a/tests/baselines/reference/predicateSemantics.js
+++ b/tests/baselines/reference/predicateSemantics.js
@@ -40,7 +40,11 @@ while ((({}))) { }
// Should be OK
console.log((cond || undefined) && 1 / cond);
-
+
+function foo(this: Object | undefined) {
+ // Should be OK
+ return this ?? 0;
+}
//// [predicateSemantics.js]
var _a, _b, _c, _d, _e, _f;
@@ -80,3 +84,7 @@ while (({})) { }
while ((({}))) { }
// Should be OK
console.log((cond || undefined) && 1 / cond);
+function foo() {
+ // Should be OK
+ return this !== null && this !== void 0 ? this : 0;
+}
diff --git a/tests/baselines/reference/predicateSemantics.symbols b/tests/baselines/reference/predicateSemantics.symbols
index 39ce291427a74..790e965f988cc 100644
--- a/tests/baselines/reference/predicateSemantics.symbols
+++ b/tests/baselines/reference/predicateSemantics.symbols
@@ -70,3 +70,12 @@ console.log((cond || undefined) && 1 / cond);
>undefined : Symbol(undefined)
>cond : Symbol(cond, Decl(predicateSemantics.ts, 0, 11))
+function foo(this: Object | undefined) {
+>foo : Symbol(foo, Decl(predicateSemantics.ts, 38, 45))
+>this : Symbol(this, Decl(predicateSemantics.ts, 40, 13))
+>Object : Symbol(Object, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
+
+ // Should be OK
+ return this ?? 0;
+>this : Symbol(this, Decl(predicateSemantics.ts, 40, 13))
+}
diff --git a/tests/baselines/reference/predicateSemantics.types b/tests/baselines/reference/predicateSemantics.types
index b4f418ce33943..3d3eba6683e25 100644
--- a/tests/baselines/reference/predicateSemantics.types
+++ b/tests/baselines/reference/predicateSemantics.types
@@ -219,3 +219,18 @@ console.log((cond || undefined) && 1 / cond);
>cond : any
> : ^^^
+function foo(this: Object | undefined) {
+>foo : (this: Object | undefined) => Object | 0
+> : ^ ^^ ^^^^^^^^^^^^^^^
+>this : Object
+> : ^^^^^^
+
+ // Should be OK
+ return this ?? 0;
+>this ?? 0 : 0 | Object
+> : ^^^^^^^^^^
+>this : Object
+> : ^^^^^^
+>0 : 0
+> : ^
+}
diff --git a/tests/cases/compiler/predicateSemantics.ts b/tests/cases/compiler/predicateSemantics.ts
index 4069c1da6eec7..d6e12b297b25b 100644
--- a/tests/cases/compiler/predicateSemantics.ts
+++ b/tests/cases/compiler/predicateSemantics.ts
@@ -37,3 +37,8 @@ while ((({}))) { }
// Should be OK
console.log((cond || undefined) && 1 / cond);
+
+function foo(this: Object | undefined) {
+ // Should be OK
+ return this ?? 0;
+}
\ No newline at end of file