Chain RHS narrowing and truthiness narrowing in assignment expression narrowing (#31348)

2026-05-06 04:35:21 -05:00 · 2019-05-13 14:41:33 -07:00
parent 546028156e
commit f140dfc30b
9 changed files with 194 additions and 15 deletions
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -16773,7 +16773,7 @@ namespace ts {
            function narrowTypeByBinaryExpression(type: Type, expr: BinaryExpression, assumeTrue: boolean): Type {
                switch (expr.operatorToken.kind) {
                    case SyntaxKind.EqualsToken:
-                        return narrowTypeByTruthiness(type, expr.left, assumeTrue);
+                        return narrowTypeByTruthiness(narrowType(type, expr.right, assumeTrue), expr.left, assumeTrue);
                    case SyntaxKind.EqualsEqualsToken:
                    case SyntaxKind.ExclamationEqualsToken:
                    case SyntaxKind.EqualsEqualsEqualsToken:
--- a/tests/baselines/reference/controlFlowForCompoundAssignmentToThisMember.js
+++ b/tests/baselines/reference/controlFlowForCompoundAssignmentToThisMember.js
@@ -0,0 +1,36 @@
+//// [controlFlowForCompoundAssignmentToThisMember.ts]
+class DatasourceCommandWidgetElement {
+    _commandBased: boolean;
+    _commandElement: unknown;
+    commandElement: unknown;
+
+    constructor(target: unknown) {
+        if (target instanceof DatasourceCommandWidgetElement) {
+            this._commandBased = true;
+            this._commandElement = target.commandElement;
+        } else {
+            this._commandBased = false;
+        }
+
+        if (this._commandBased = (target instanceof DatasourceCommandWidgetElement)) {
+            this._commandElement = target.commandElement;
+        }
+    }
+}
+
+//// [controlFlowForCompoundAssignmentToThisMember.js]
+var DatasourceCommandWidgetElement = /** @class */ (function () {
+    function DatasourceCommandWidgetElement(target) {
+        if (target instanceof DatasourceCommandWidgetElement) {
+            this._commandBased = true;
+            this._commandElement = target.commandElement;
+        }
+        else {
+            this._commandBased = false;
+        }
+        if (this._commandBased = (target instanceof DatasourceCommandWidgetElement)) {
+            this._commandElement = target.commandElement;
+        }
+    }
+    return DatasourceCommandWidgetElement;
+}());
--- a/tests/baselines/reference/controlFlowForCompoundAssignmentToThisMember.symbols
+++ b/tests/baselines/reference/controlFlowForCompoundAssignmentToThisMember.symbols
@@ -0,0 +1,57 @@
+=== tests/cases/compiler/controlFlowForCompoundAssignmentToThisMember.ts ===
+class DatasourceCommandWidgetElement {
+>DatasourceCommandWidgetElement : Symbol(DatasourceCommandWidgetElement, Decl(controlFlowForCompoundAssignmentToThisMember.ts, 0, 0))
+
+    _commandBased: boolean;
+>_commandBased : Symbol(DatasourceCommandWidgetElement._commandBased, Decl(controlFlowForCompoundAssignmentToThisMember.ts, 0, 38))
+
+    _commandElement: unknown;
+>_commandElement : Symbol(DatasourceCommandWidgetElement._commandElement, Decl(controlFlowForCompoundAssignmentToThisMember.ts, 1, 27))
+
+    commandElement: unknown;
+>commandElement : Symbol(DatasourceCommandWidgetElement.commandElement, Decl(controlFlowForCompoundAssignmentToThisMember.ts, 2, 29))
+
+    constructor(target: unknown) {
+>target : Symbol(target, Decl(controlFlowForCompoundAssignmentToThisMember.ts, 5, 16))
+
+        if (target instanceof DatasourceCommandWidgetElement) {
+>target : Symbol(target, Decl(controlFlowForCompoundAssignmentToThisMember.ts, 5, 16))
+>DatasourceCommandWidgetElement : Symbol(DatasourceCommandWidgetElement, Decl(controlFlowForCompoundAssignmentToThisMember.ts, 0, 0))
+
+            this._commandBased = true;
+>this._commandBased : Symbol(DatasourceCommandWidgetElement._commandBased, Decl(controlFlowForCompoundAssignmentToThisMember.ts, 0, 38))
+>this : Symbol(DatasourceCommandWidgetElement, Decl(controlFlowForCompoundAssignmentToThisMember.ts, 0, 0))
+>_commandBased : Symbol(DatasourceCommandWidgetElement._commandBased, Decl(controlFlowForCompoundAssignmentToThisMember.ts, 0, 38))
+
+            this._commandElement = target.commandElement;
+>this._commandElement : Symbol(DatasourceCommandWidgetElement._commandElement, Decl(controlFlowForCompoundAssignmentToThisMember.ts, 1, 27))
+>this : Symbol(DatasourceCommandWidgetElement, Decl(controlFlowForCompoundAssignmentToThisMember.ts, 0, 0))
+>_commandElement : Symbol(DatasourceCommandWidgetElement._commandElement, Decl(controlFlowForCompoundAssignmentToThisMember.ts, 1, 27))
+>target.commandElement : Symbol(DatasourceCommandWidgetElement.commandElement, Decl(controlFlowForCompoundAssignmentToThisMember.ts, 2, 29))
+>target : Symbol(target, Decl(controlFlowForCompoundAssignmentToThisMember.ts, 5, 16))
+>commandElement : Symbol(DatasourceCommandWidgetElement.commandElement, Decl(controlFlowForCompoundAssignmentToThisMember.ts, 2, 29))
+
+        } else {
+            this._commandBased = false;
+>this._commandBased : Symbol(DatasourceCommandWidgetElement._commandBased, Decl(controlFlowForCompoundAssignmentToThisMember.ts, 0, 38))
+>this : Symbol(DatasourceCommandWidgetElement, Decl(controlFlowForCompoundAssignmentToThisMember.ts, 0, 0))
+>_commandBased : Symbol(DatasourceCommandWidgetElement._commandBased, Decl(controlFlowForCompoundAssignmentToThisMember.ts, 0, 38))
+        }
+
+        if (this._commandBased = (target instanceof DatasourceCommandWidgetElement)) {
+>this._commandBased : Symbol(DatasourceCommandWidgetElement._commandBased, Decl(controlFlowForCompoundAssignmentToThisMember.ts, 0, 38))
+>this : Symbol(DatasourceCommandWidgetElement, Decl(controlFlowForCompoundAssignmentToThisMember.ts, 0, 0))
+>_commandBased : Symbol(DatasourceCommandWidgetElement._commandBased, Decl(controlFlowForCompoundAssignmentToThisMember.ts, 0, 38))
+>target : Symbol(target, Decl(controlFlowForCompoundAssignmentToThisMember.ts, 5, 16))
+>DatasourceCommandWidgetElement : Symbol(DatasourceCommandWidgetElement, Decl(controlFlowForCompoundAssignmentToThisMember.ts, 0, 0))
+
+            this._commandElement = target.commandElement;
+>this._commandElement : Symbol(DatasourceCommandWidgetElement._commandElement, Decl(controlFlowForCompoundAssignmentToThisMember.ts, 1, 27))
+>this : Symbol(DatasourceCommandWidgetElement, Decl(controlFlowForCompoundAssignmentToThisMember.ts, 0, 0))
+>_commandElement : Symbol(DatasourceCommandWidgetElement._commandElement, Decl(controlFlowForCompoundAssignmentToThisMember.ts, 1, 27))
+>target.commandElement : Symbol(DatasourceCommandWidgetElement.commandElement, Decl(controlFlowForCompoundAssignmentToThisMember.ts, 2, 29))
+>target : Symbol(target, Decl(controlFlowForCompoundAssignmentToThisMember.ts, 5, 16))
+>commandElement : Symbol(DatasourceCommandWidgetElement.commandElement, Decl(controlFlowForCompoundAssignmentToThisMember.ts, 2, 29))
+        }
+    }
+}
--- a/tests/baselines/reference/controlFlowForCompoundAssignmentToThisMember.types
+++ b/tests/baselines/reference/controlFlowForCompoundAssignmentToThisMember.types
@@ -0,0 +1,67 @@
+=== tests/cases/compiler/controlFlowForCompoundAssignmentToThisMember.ts ===
+class DatasourceCommandWidgetElement {
+>DatasourceCommandWidgetElement : DatasourceCommandWidgetElement
+
+    _commandBased: boolean;
+>_commandBased : boolean
+
+    _commandElement: unknown;
+>_commandElement : unknown
+
+    commandElement: unknown;
+>commandElement : unknown
+
+    constructor(target: unknown) {
+>target : unknown
+
+        if (target instanceof DatasourceCommandWidgetElement) {
+>target instanceof DatasourceCommandWidgetElement : boolean
+>target : unknown
+>DatasourceCommandWidgetElement : typeof DatasourceCommandWidgetElement
+
+            this._commandBased = true;
+>this._commandBased = true : true
+>this._commandBased : boolean
+>this : this
+>_commandBased : boolean
+>true : true
+
+            this._commandElement = target.commandElement;
+>this._commandElement = target.commandElement : unknown
+>this._commandElement : unknown
+>this : this
+>_commandElement : unknown
+>target.commandElement : unknown
+>target : DatasourceCommandWidgetElement
+>commandElement : unknown
+
+        } else {
+            this._commandBased = false;
+>this._commandBased = false : false
+>this._commandBased : boolean
+>this : this
+>_commandBased : boolean
+>false : false
+        }
+
+        if (this._commandBased = (target instanceof DatasourceCommandWidgetElement)) {
+>this._commandBased = (target instanceof DatasourceCommandWidgetElement) : boolean
+>this._commandBased : boolean
+>this : this
+>_commandBased : boolean
+>(target instanceof DatasourceCommandWidgetElement) : boolean
+>target instanceof DatasourceCommandWidgetElement : boolean
+>target : unknown
+>DatasourceCommandWidgetElement : typeof DatasourceCommandWidgetElement
+
+            this._commandElement = target.commandElement;
+>this._commandElement = target.commandElement : unknown
+>this._commandElement : unknown
+>this : this
+>_commandElement : unknown
+>target.commandElement : unknown
+>target : DatasourceCommandWidgetElement
+>commandElement : unknown
+        }
+    }
+}
--- a/tests/baselines/reference/controlFlowTruthiness.types
+++ b/tests/baselines/reference/controlFlowTruthiness.types
@@ -111,7 +111,7 @@ function f5() {
 >x : string

        y; // string | undefined
->y : string | undefined
+>y : string
    }
    else {
        x; // string | undefined
--- a/tests/baselines/reference/typeGuardsInConditionalExpression.types
+++ b/tests/baselines/reference/typeGuardsInConditionalExpression.types
@@ -211,11 +211,11 @@ function foo8(x: number | string | boolean) {
 >typeof x === "boolean"        ? x // boolean        : x == 10 : boolean
 >typeof x === "boolean" : boolean
 >typeof x : "string" | "number" | "bigint" | "boolean" | "symbol" | "undefined" | "object" | "function"
->x : number | boolean
+>x : number | true
 >"boolean" : "boolean"

        ? x // boolean
->x : boolean
+>x : true

        : x == 10)); // boolean
 >x == 10 : boolean
@@ -286,7 +286,7 @@ function foo10(x: number | string | boolean) {
        && typeof x === "number"
 >typeof x === "number" : boolean
 >typeof x : "string" | "number" | "bigint" | "boolean" | "symbol" | "undefined" | "object" | "function"
->x : number | boolean
+>x : number | true
 >"number" : "number"

        && x.toString()); // x is number
@@ -326,7 +326,7 @@ function foo11(x: number | string | boolean) {
        && typeof x === "number"
 >typeof x === "number" : boolean
 >typeof x : "string" | "number" | "bigint" | "boolean" | "symbol" | "undefined" | "object" | "function"
->x : number | boolean
+>x : number | true
 >"number" : "number"

        && (x = 10) // assignment to x
@@ -379,7 +379,7 @@ function foo12(x: number | string | boolean) {
        && typeof x === "number"
 >typeof x === "number" : boolean
 >typeof x : "string" | "number" | "bigint" | "boolean" | "symbol" | "undefined" | "object" | "function"
->x : number | boolean
+>x : number | true
 >"number" : "number"

        && x); // x is number
--- a/tests/baselines/reference/typeGuardsInRightOperandOfAndAndOperator.types
+++ b/tests/baselines/reference/typeGuardsInRightOperandOfAndAndOperator.types
@@ -102,11 +102,11 @@ function foo5(x: number | string | boolean) {
 >typeof x !== "number"  // number | boolean        && x : boolean
 >typeof x !== "number" : boolean
 >typeof x : "string" | "number" | "bigint" | "boolean" | "symbol" | "undefined" | "object" | "function"
->x : number | boolean
+>x : number | true
 >"number" : "number"

        && x));   // boolean
->x : boolean
+>x : true
 }
 function foo6(x: number | string | boolean) {
 >foo6 : (x: string | number | boolean) => boolean
@@ -167,7 +167,7 @@ function foo7(x: number | string | boolean) {
 >typeof x === "number"        // change value of x        ? ((x = 10) && x.toString()) // x is number        // do not change value        : ((y = x) && x.toString()) : string
 >typeof x === "number" : boolean
 >typeof x : "string" | "number" | "bigint" | "boolean" | "symbol" | "undefined" | "object" | "function"
->x : number | boolean
+>x : number | true
 >"number" : "number"

        // change value of x
@@ -187,13 +187,13 @@ function foo7(x: number | string | boolean) {
        : ((y = x) && x.toString()))); // x is boolean
 >((y = x) && x.toString()) : string
 >(y = x) && x.toString() : string
->(y = x) : boolean
->y = x : boolean
+>(y = x) : true
+>y = x : true
 >y : string | number | boolean
->x : boolean
+>x : true
 >x.toString() : string
 >x.toString : () => string
->x : boolean
+>x : true
 >toString : () => string
 }

--- a/tests/baselines/reference/typeGuardsInRightOperandOfOrOrOperator.types
+++ b/tests/baselines/reference/typeGuardsInRightOperandOfOrOrOperator.types
@@ -194,7 +194,7 @@ function foo7(x: number | string | boolean) {
 >x : boolean
 >x.toString() : string
 >x.toString : () => string
->x : boolean
+>x : true
 >toString : () => string
 }

--- a/tests/cases/compiler/controlFlowForCompoundAssignmentToThisMember.ts
+++ b/tests/cases/compiler/controlFlowForCompoundAssignmentToThisMember.ts
@@ -0,0 +1,19 @@
+
+class DatasourceCommandWidgetElement {
+    _commandBased: boolean;
+    _commandElement: unknown;
+    commandElement: unknown;
+
+    constructor(target: unknown) {
+        if (target instanceof DatasourceCommandWidgetElement) {
+            this._commandBased = true;
+            this._commandElement = target.commandElement;
+        } else {
+            this._commandBased = false;
+        }
+
+        if (this._commandBased = (target instanceof DatasourceCommandWidgetElement)) {
+            this._commandElement = target.commandElement;
+        }
+    }
+}