refactor(linter): use "parsed pattern" in no_div_regex rule. (#5417)

Part of #5416, Paves the road for upcoming refactors by adding the `oxc_regular_expression` dependency and a helper method for ease of access.

crates/oxc_ast/src/ast_impl/literal.rs

@@ -11,6 +11,7 @@ use std::{
 };
 
 use oxc_allocator::CloneIn;
+use oxc_regular_expression::ast::Pattern;
 use oxc_span::{cmp::ContentEq, Atom, Span};
 use oxc_syntax::number::NumberBase;
 
@@ -137,6 +138,28 @@ impl<'a> RegExpPattern<'a> {
             Self::Pattern(pat) => pat.span.source_text(source_text),
         }
     }
+
+    /// # Panics
+    /// If `self` is anything but `RegExpPattern::Pattern`.
+    pub fn require_pattern(&self) -> &Pattern<'a> {
+        if let Some(it) = self.as_pattern() {
+            it
+        } else {
+            unreachable!(
+                "Required `{}` to be `{}`",
+                stringify!(RegExpPattern),
+                stringify!(Pattern)
+            );
+        }
+    }
+
+    pub fn as_pattern(&self) -> Option<&Pattern<'a>> {
+        if let Self::Pattern(it) = self {
+            Some(it.as_ref())
+        } else {
+            None
+        }
+    }
 }
 
 impl<'a> fmt::Display for RegExpPattern<'a> {

crates/oxc_linter/Cargo.toml

@@ -20,18 +20,19 @@ workspace = true
 doctest = false
 
 [dependencies]
-oxc_allocator   = { workspace = true }
-oxc_parser      = { workspace = true }
-oxc_span        = { workspace = true, features = ["schemars", "serialize"] }
-oxc_ast         = { workspace = true }
-oxc_cfg         = { workspace = true }
-oxc_diagnostics = { workspace = true }
-oxc_index       = { workspace = true }
-oxc_macros      = { workspace = true }
-oxc_semantic    = { workspace = true }
-oxc_syntax      = { workspace = true }
-oxc_codegen     = { workspace = true }
-oxc_resolver    = { workspace = true }
+oxc_allocator          = { workspace = true }
+oxc_parser             = { workspace = true }
+oxc_span               = { workspace = true, features = ["schemars", "serialize"] }
+oxc_ast                = { workspace = true }
+oxc_cfg                = { workspace = true }
+oxc_diagnostics        = { workspace = true }
+oxc_index              = { workspace = true }
+oxc_macros             = { workspace = true }
+oxc_semantic           = { workspace = true }
+oxc_syntax             = { workspace = true }
+oxc_codegen            = { workspace = true }
+oxc_resolver           = { workspace = true }
+oxc_regular_expression = { workspace = true }
 
 rayon               = { workspace = true }
 bitflags            = { workspace = true }

crates/oxc_linter/src/rules/eslint/no_div_regex.rs

@@ -1,6 +1,7 @@
 use oxc_ast::AstKind;
 use oxc_diagnostics::OxcDiagnostic;
 use oxc_macros::declare_oxc_lint;
+use oxc_regular_expression::ast::{CharacterKind, Term};
 use oxc_span::Span;
 
 use crate::{context::LintContext, rule::Rule, AstNode};
@@ -36,7 +37,14 @@ declare_oxc_lint!(
 impl Rule for NoDivRegex {
     fn run<'a>(&self, node: &AstNode<'a>, ctx: &LintContext<'a>) {
         if let AstKind::RegExpLiteral(lit) = node.kind() {
-            if lit.regex.pattern.source_text(ctx.source_text()).starts_with('=') {
+            let Some(pattern) = lit.regex.pattern.as_pattern() else { return };
+            if pattern
+                .body
+                .body
+                .first()
+                .and_then(|it| it.body.first())
+                .is_some_and(|it| matches!(it, Term::Character(ch) if ch.kind == CharacterKind::Symbol && ch.value == '=' as u32))
+            {
                 ctx.diagnostic_with_fix(no_div_regex_diagnostic(lit.span), |fixer| {
                     let span = Span::sized(lit.span.start + 1, 1);
                     fixer.replace(span, "[=]")