fix(compiler): more robust logic to check if regex can be optimized

crisbeto · atscott · commit a56f1cdf8fa2 · 2026-06-03T18:53:41.000Z
Currently we only skip regex optimization if it has the `g` flag, however regexes can also have a state with the `y` flag. These changes move to an allowlist model where we only optimize for a set of know flags. (cherry picked from commit 636cc94)
diff --git a/packages/compiler-cli/test/compliance/test_cases/r3_compiler_compliance/components_and_directives/value_composition/GOLDEN_PARTIAL.js b/packages/compiler-cli/test/compliance/test_cases/r3_compiler_compliance/components_and_directives/value_composition/GOLDEN_PARTIAL.js
@@ -980,6 +980,33 @@ export declare class TestComp {
     static &#629;cmp: i0.&#629;&#629;ComponentDeclaration<TestComp, "ng-component", never, {}, {}, never, never, true, never>;
 }
 
+/****************************************************************************************************
+ * PARTIAL FILE: regular_expression_with_sticky_flag.js
+ ****************************************************************************************************/
+import { Component } from '@angular/core';
+import * as i0 from "@angular/core";
+export class TestComp {
+    value = '123';
+    static &#629;fac = i0.&#629;&#629;ngDeclareFactory({ minVersion: "12.0.0", version: "0.0.0-PLACEHOLDER", ngImport: i0, type: TestComp, deps: [], target: i0.&#629;&#629;FactoryTarget.Component });
+    static &#629;cmp = i0.&#629;&#629;ngDeclareComponent({ minVersion: "14.0.0", version: "0.0.0-PLACEHOLDER", type: TestComp, isStandalone: true, selector: "ng-component", ngImport: i0, template: `{{/^hello/y.test(value)}}`, isInline: true });
+}
+i0.&#629;&#629;ngDeclareClassMetadata({ minVersion: "12.0.0", version: "0.0.0-PLACEHOLDER", ngImport: i0, type: TestComp, decorators: [{
+            type: Component,
+            args: [{
+                    template: `{{/^hello/y.test(value)}}`,
+                }]
+        }] });
+
+/****************************************************************************************************
+ * PARTIAL FILE: regular_expression_with_sticky_flag.d.ts
+ ****************************************************************************************************/
+import * as i0 from "@angular/core";
+export declare class TestComp {
+    value: string;
+    static &#629;fac: i0.&#629;&#629;FactoryDeclaration<TestComp, never>;
+    static &#629;cmp: i0.&#629;&#629;ComponentDeclaration<TestComp, "ng-component", never, {}, {}, never, never, true, never>;
+}
+
 /****************************************************************************************************
  * PARTIAL FILE: call_rest.js
  ****************************************************************************************************/
diff --git a/packages/compiler-cli/test/compliance/test_cases/r3_compiler_compliance/components_and_directives/value_composition/TEST_CASES.json b/packages/compiler-cli/test/compliance/test_cases/r3_compiler_compliance/components_and_directives/value_composition/TEST_CASES.json
@@ -317,6 +317,16 @@
         }
       ]
     },
+    {
+      "description": "should not optimize sticky regular expressions",
+      "inputFiles": ["regular_expression_with_sticky_flag.ts"],
+      "expectations": [
+        {
+          "failureMessage": "Invalid template",
+          "files": ["regular_expression_with_sticky_flag.js"]
+        }
+      ]
+    },
     {
       "description": "should support rest arguments in a function call",
       "inputFiles": ["call_rest.ts"],
diff --git a/packages/compiler-cli/test/compliance/test_cases/r3_compiler_compliance/components_and_directives/value_composition/regular_expression_with_sticky_flag.js b/packages/compiler-cli/test/compliance/test_cases/r3_compiler_compliance/components_and_directives/value_composition/regular_expression_with_sticky_flag.js
@@ -0,0 +1,8 @@
+function TestComp_Template(rf, ctx) {
+  if (rf & 1) {
+    $r3$.&#629;&#629;text(0);
+  }
+  if (rf & 2) {
+    $r3$.&#629;&#629;textInterpolate(/^hello/y.test(ctx.value));
+  }
+}
diff --git a/packages/compiler-cli/test/compliance/test_cases/r3_compiler_compliance/components_and_directives/value_composition/regular_expression_with_sticky_flag.ts b/packages/compiler-cli/test/compliance/test_cases/r3_compiler_compliance/components_and_directives/value_composition/regular_expression_with_sticky_flag.ts
@@ -0,0 +1,8 @@
+import {Component} from '@angular/core';
+
+@Component({
+  template: `{{/^hello/y.test(value)}}`,
+})
+export class TestComp {
+  value = '123';
+}
diff --git a/packages/compiler-cli/test/compliance/test_cases/r3_compiler_compliance/components_and_directives/value_composition/regular_expression_with_sticky_flag_isolated.golden.d.ts b/packages/compiler-cli/test/compliance/test_cases/r3_compiler_compliance/components_and_directives/value_composition/regular_expression_with_sticky_flag_isolated.golden.d.ts
@@ -0,0 +1,6 @@
+import * as i0 from "@angular/core";
+export declare class TestComp {
+    value: string;
+    static &#629;fac: i0.&#629;&#629;FactoryDeclaration<TestComp, never>;
+    static &#629;cmp: i0.&#629;&#629;ComponentDeclaration<TestComp, "ng-component", never, {}, {}, never, never, true, never>;
+}
diff --git a/packages/compiler/src/template/pipeline/src/phases/regular_expression_optimization.ts b/packages/compiler/src/template/pipeline/src/phases/regular_expression_optimization.ts
@@ -12,18 +12,17 @@ import * as ir from '../../ir';
 
 import type {CompilationJob} from '../compilation';
 
+/** Regex flags that can be safely optimized. */
+const SAFE_REGEX_FLAGS = new Set(['d', 'i', 'm', 's', 'u', 'v']);
+
 /** Optimizes regular expressions used in expressions. */
 export function optimizeRegularExpressions(job: CompilationJob): void {
   for (const view of job.units) {
     for (const op of view.ops()) {
       ir.transformExpressionsInOp(
         op,
         (expr) => {
-          if (
-            expr instanceof o.RegularExpressionLiteralExpr &&
-            // We can't optimize global regexes, because they're stateful.
-            (expr.flags === null || !expr.flags.includes('g'))
-          ) {
+          if (expr instanceof o.RegularExpressionLiteralExpr && canOptimizeRegex(expr)) {
             return job.pool.getSharedConstant(new RegularExpressionConstant(), expr);
           }
           return expr;
@@ -34,6 +33,20 @@ export function optimizeRegularExpressions(job: CompilationJob): void {
   }
 }
 
+function canOptimizeRegex(expr: o.RegularExpressionLiteralExpr): boolean {
+  if (!expr.flags) {
+    return true;
+  }
+
+  for (let i = 0; i < expr.flags.length; i++) {
+    if (!SAFE_REGEX_FLAGS.has(expr.flags[i])) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
 class RegularExpressionConstant extends GenericKeyFn implements SharedConstantDefinition {
   toSharedConstantDeclaration(declName: string, keyExpr: o.Expression): o.Statement {
     return new o.DeclareVarStmt(declName, keyExpr, undefined, o.StmtModifier.Final);

Original file line number	Diff line number	Diff line change
`@@ -317,6 +317,16 @@`
`317`	`317`	`}`
`318`	`318`	`]`
`319`	`319`	`},`
	`320`	`+ {`
	`321`	`+ "description": "should not optimize sticky regular expressions",`
	`322`	`+ "inputFiles": ["regular_expression_with_sticky_flag.ts"],`
	`323`	`+ "expectations": [`
	`324`	`+ {`
	`325`	`+ "failureMessage": "Invalid template",`
	`326`	`+ "files": ["regular_expression_with_sticky_flag.js"]`
	`327`	`+ }`
	`328`	`+ ]`
	`329`	`+ },`
`320`	`330`	`{`
`321`	`331`	`"description": "should support rest arguments in a function call",`
`322`	`332`	`"inputFiles": ["call_rest.ts"],`
-Original file line number
+Diff line change
@@ @@ -0,0 +1,8 @@ @@
 +function TestComp_Template(rf, ctx) {
 +  if (rf & 1) {
 +    $r3$.ɵɵtext(0);
 +  }
 +  if (rf & 2) {
 +    $r3$.ɵɵtextInterpolate(/^hello/y.test(ctx.value));
 +  }
 +}