verilog: make generate-label-prefix configurable via style_regex

Fixes #2288: allow users to configure the allowed label prefix via
style_regex instead of hardcoded g_/gen_. Default regex (g_|gen_).*
preserves existing behavior. Uses RE2 FullMatch and config-utils SetRegex
pattern similar to enum-name-style.

Signed-off-by: Talha-Dmr <>
Signed-off-by: Talha-Dmr <talhademir-100@hotmail.com>

verible/verilog/analysis/checkers/BUILD

diff --git a/verible/verilog/analysis/checkers/BUILD b/verible/verilog/analysis/checkers/BUILD
index bd3a98b..2151eaa 100644
--- a/verible/verilog/analysis/checkers/BUILD
+++ b/verible/verilog/analysis/checkers/BUILD
@@ -817,6 +817,7 @@
         "//verible/common/analysis:syntax-tree-lint-rule",
         "//verible/common/analysis/matcher",
         "//verible/common/analysis/matcher:bound-symbol-manager",
+        "//verible/common/text:config-utils",
         "//verible/common/text:symbol",
         "//verible/common/text:syntax-tree-context",
         "//verible/common/text:token-info",
@@ -826,7 +827,9 @@
         "//verible/verilog/CST:verilog-nonterminals",
         "//verible/verilog/analysis:descriptions",
         "//verible/verilog/analysis:lint-rule-registry",
+        "@abseil-cpp//absl/status",
         "@abseil-cpp//absl/strings",
+        "@re2",
     ],
     alwayslink = 1,
 )

verible/verilog/analysis/checkers/generate-label-prefix-rule.cc

diff --git a/verible/verilog/analysis/checkers/generate-label-prefix-rule.cc b/verible/verilog/analysis/checkers/generate-label-prefix-rule.cc
index c8822ce..53fe7a1 100644
--- a/verible/verilog/analysis/checkers/generate-label-prefix-rule.cc
+++ b/verible/verilog/analysis/checkers/generate-label-prefix-rule.cc
@@ -14,12 +14,15 @@
 
 #include "verible/verilog/analysis/checkers/generate-label-prefix-rule.h"
 
+#include <memory>
 #include <string_view>
 
-#include "absl/strings/match.h"
+#include "absl/strings/str_cat.h"
+#include "re2/re2.h"
 #include "verible/common/analysis/lint-rule-status.h"
 #include "verible/common/analysis/matcher/bound-symbol-manager.h"
 #include "verible/common/analysis/matcher/matcher.h"
+#include "verible/common/text/config-utils.h"
 #include "verible/common/text/symbol.h"
 #include "verible/common/text/syntax-tree-context.h"
 #include "verible/common/text/token-info.h"
@@ -38,22 +41,35 @@
 // Register the lint rule
 VERILOG_REGISTER_LINT_RULE(GenerateLabelPrefixRule);
 
-static constexpr std::string_view kMessage =
-    "All generate block labels must start with g_ or gen_";
+static constexpr std::string_view kDefaultStyleRegex = "(g_|gen_).*";
 
-// TODO(fangism): and be lower_snake_case?
-// TODO(fangism): generalize to a configurable pattern and
-// rename this class/rule to GenerateLabelNamingStyle?
+GenerateLabelPrefixRule::GenerateLabelPrefixRule()
+    : style_regex_(
+          std::make_unique<re2::RE2>(kDefaultStyleRegex, re2::RE2::Quiet)) {}
 
 const LintRuleDescriptor &GenerateLabelPrefixRule::GetDescriptor() {
   static const LintRuleDescriptor d{
       .name = "generate-label-prefix",
       .topic = "generate-constructs",
-      .desc = "Checks that every generate block label starts with g_ or gen_.",
+      .desc =
+          "Checks that every generate block label matches the regex defined by "
+          "style_regex. The default regex requires labels to start with g_ or "
+          "gen_. Refer to https://github.com/chipsalliance/verible/tree/master/"
+          "verilog/tools/lint#readme for more detail on verible regex "
+          "patterns.",
+      .param = {{"style_regex", std::string(kDefaultStyleRegex),
+                 "A regex used to check generate label style."}},
   };
   return d;
 }
 
+std::string GenerateLabelPrefixRule::CreateViolationMessage() const {
+  return absl::StrCat(
+      "Generate block label does not match the naming convention defined by "
+      "regex pattern: ",
+      style_regex_->pattern());
+}
+
 // Matches begin statements
 static const Matcher &BlockMatcher() {
   static const Matcher matcher(NodekGenerateBlock());
@@ -84,15 +100,23 @@
       }
 
       if (label != nullptr) {
-        if (!(absl::StartsWith(label->text(), "g_") ||
-              absl::StartsWith(label->text(), "gen_"))) {
-          violations_.insert(verible::LintViolation(*label, kMessage, context));
+        if (!RE2::FullMatch(label->text(), *style_regex_)) {
+          violations_.insert(verible::LintViolation(
+              *label, CreateViolationMessage(), context));
         }
       }
     }
   }
 }
 
+absl::Status GenerateLabelPrefixRule::Configure(
+    std::string_view configuration) {
+  using verible::config::SetRegex;
+  absl::Status s = verible::ParseNameValues(
+      configuration, {{"style_regex", SetRegex(&style_regex_)}});
+  return s;
+}
+
 verible::LintRuleStatus GenerateLabelPrefixRule::Report() const {
   return verible::LintRuleStatus(violations_, GetDescriptor());
 }

verible/verilog/analysis/checkers/generate-label-prefix-rule.h

diff --git a/verible/verilog/analysis/checkers/generate-label-prefix-rule.h b/verible/verilog/analysis/checkers/generate-label-prefix-rule.h
index 9090cf3..e18df9c 100644
--- a/verible/verilog/analysis/checkers/generate-label-prefix-rule.h
+++ b/verible/verilog/analysis/checkers/generate-label-prefix-rule.h
@@ -15,8 +15,13 @@
 #ifndef VERIBLE_VERILOG_ANALYSIS_CHECKERS_GENERATE_LABEL_PREFIX_RULE_H_
 #define VERIBLE_VERILOG_ANALYSIS_CHECKERS_GENERATE_LABEL_PREFIX_RULE_H_
 
+#include <memory>
 #include <set>
+#include <string>
+#include <string_view>
 
+#include "absl/status/status.h"
+#include "re2/re2.h"
 #include "verible/common/analysis/lint-rule-status.h"
 #include "verible/common/analysis/syntax-tree-lint-rule.h"
 #include "verible/common/text/symbol.h"
@@ -27,20 +32,28 @@
 namespace analysis {
 
 // GenerateLabelPrefixRule checks that all generate block labels start
-// with g_ or gen_
+// with g_ or gen_ (configurable via style_regex)
 class GenerateLabelPrefixRule : public verible::SyntaxTreeLintRule {
  public:
   using rule_type = verible::SyntaxTreeLintRule;
 
+  GenerateLabelPrefixRule();
+
   static const LintRuleDescriptor &GetDescriptor();
 
+  std::string CreateViolationMessage() const;
+
   void HandleSymbol(const verible::Symbol &symbol,
                     const verible::SyntaxTreeContext &context) final;
 
   verible::LintRuleStatus Report() const final;
 
+  absl::Status Configure(std::string_view configuration) final;
+
  private:
   std::set<verible::LintViolation> violations_;
+
+  std::unique_ptr<re2::RE2> style_regex_;
 };
 
 }  // namespace analysis