feat: improve get literal value for conditional expression (#6000)

ahabhgk · lukastaegert · web-flow · commit 7be41cb5a5a4 · 2025-07-12T05:22:17.000Z
* feat: improve get literal value for conditional expression

* more tests

* Remove unnecessary comparison

---------

Co-authored-by: Lukas Taegert-Atkinson &lt;lukastaegert@users.noreply.github.com&gt;
Co-authored-by: Lukas Taegert-Atkinson &lt;lukas.taegert-atkinson@tngtech.com&gt;
diff --git a/src/ast/nodes/ConditionalExpression.ts b/src/ast/nodes/ConditionalExpression.ts
@@ -16,7 +16,7 @@ import { tryCastLiteralValueToBoolean } from '../utils/tryCastLiteralValueToBool
 import type * as NodeType from './NodeType';
 import { Flag, isFlagSet, setFlag } from './shared/BitFlags';
 import type { ExpressionEntity, LiteralValueOrUnknown } from './shared/Expression';
-import { UnknownValue } from './shared/Expression';
+import { UnknownFalsyValue, UnknownTruthyValue, UnknownValue } from './shared/Expression';
 import { MultiExpression } from './shared/MultiExpression';
 import type { ExpressionNode, IncludeChildren } from './shared/Node';
 import { doNotDeoptimize, NodeBase, onlyIncludeSelfNoDeoptimize } from './shared/Node';
@@ -78,7 +78,18 @@ export default class ConditionalExpression extends NodeBase implements Deoptimiz
 		origin: DeoptimizableEntity
 	): LiteralValueOrUnknown {
 		const usedBranch = this.getUsedBranch();
-		if (!usedBranch) return UnknownValue;
+		if (!usedBranch) {
+			const consequentValue = this.consequent.getLiteralValueAtPath(path, recursionTracker, origin);
+			const castedConsequentValue = tryCastLiteralValueToBoolean(consequentValue);
+			if (castedConsequentValue === UnknownValue) return UnknownValue;
+			const alternateValue = this.alternate.getLiteralValueAtPath(path, recursionTracker, origin);
+			const castedAlternateValue = tryCastLiteralValueToBoolean(alternateValue);
+			if (castedConsequentValue !== castedAlternateValue) return UnknownValue;
+			this.expressionsToBeDeoptimized.push(origin);
+			if (consequentValue !== alternateValue)
+				return castedConsequentValue ? UnknownTruthyValue : UnknownFalsyValue;
+			return consequentValue;
+		}
 		this.expressionsToBeDeoptimized.push(origin);
 		return usedBranch.getLiteralValueAtPath(path, recursionTracker, origin);
 	}
diff --git a/test/form/samples/treeshake-if-statement/_expected.js b/test/form/samples/treeshake-if-statement/_expected.js
@@ -5,3 +5,9 @@
 if (typeof parseInt === 'function' ?? 'a' === 'a') {
 	assert.ok(true);
 }
+
+if (!(unknownGlobal ? 'asdf' : true)) ;
+
+if (unknownGlobal ? 0 : false) ;
+
+if (!(unknownGlobal ? 'a' === 'a' : true)) ;
diff --git a/test/form/samples/treeshake-if-statement/main.js b/test/form/samples/treeshake-if-statement/main.js
@@ -9,3 +9,15 @@ if (typeof parseInt === 'function' || 'a' === 'a') {
 if (typeof parseInt === 'function' ?? 'a' === 'a') {
 	assert.ok(true);
 }
+
+if (!(unknownGlobal ? 'asdf' : true)) {
+	assert.ok(false);
+}
+
+if (unknownGlobal ? 0 : false) {
+	assert.ok(false);
+}
+
+if (!(unknownGlobal ? 'a' === 'a' : true)) {
+	assert.ok(false);
+}
