From 54a0e018059037eb81d59268f2713370e6227d3e Mon Sep 17 00:00:00 2001
From: Tim Wojtulewicz <tim@corelight.com>
Date: Wed, 16 Apr 2025 18:35:26 -0700
Subject: [PATCH] binpac: Wrap generated switch statements in NOLINTs for
 bugprone-branch-clone

Binpac generates a lot of switch statements with repeated blocks in
them (typically empty blocks). Running clang-tidy on the generated code
with bugprone-branch-clone generates a lot of warnings. Instead of
doing a ton of analysis in binpac to avoid generating the duplicates,
just mark any switch generated with an annotation to avoid reporting
them.
---
 tools/binpac/src/pac_case.cc   | 6 ++++++
 tools/binpac/src/pac_expr.cc   | 2 ++
 tools/binpac/src/pac_record.cc | 2 ++
 tools/binpac/src/pac_type.cc   | 2 ++
 4 files changed, 12 insertions(+)

diff --git a/tools/binpac/src/pac_case.cc b/tools/binpac/src/pac_case.cc
index 187eaf37c8..cc629d2253 100644
--- a/tools/binpac/src/pac_case.cc
+++ b/tools/binpac/src/pac_case.cc
@@ -117,6 +117,7 @@ void CaseType::GenCleanUpCode(Output* out_cc, Env* env) {
     Type::GenCleanUpCode(out_cc, env);
 
     env->set_in_branch(true);
+    out_cc->println("// NOLINTBEGIN(bugprone-branch-clone)");
     out_cc->println("switch ( %s ) {", env->RValue(index_var_));
     out_cc->inc_indent();
     foreach (i, CaseFieldList, cases_) {
@@ -125,6 +126,7 @@ void CaseType::GenCleanUpCode(Output* out_cc, Env* env) {
     }
     out_cc->dec_indent();
     out_cc->println("}");
+    out_cc->println("// NOLINTEND(bugprone-branch-clone)");
     env->set_in_branch(false);
 }
 
@@ -141,6 +143,7 @@ void CaseType::DoGenParseCode(Output* out_cc, Env* env, const DataPtr& data, int
     env->SetEvaluated(index_var_);
 
     env->set_in_branch(true);
+    out_cc->println("// NOLINTBEGIN(bugprone-branch-clone)");
     out_cc->println("switch ( %s ) {", env->RValue(index_var_));
     out_cc->inc_indent();
     bool has_default_case = false;
@@ -161,6 +164,7 @@ void CaseType::DoGenParseCode(Output* out_cc, Env* env, const DataPtr& data, int
     }
     out_cc->dec_indent();
     out_cc->println("}");
+    out_cc->println("// NOLINTEND(bugprone-branch-clone)");
     env->set_in_branch(false);
 
     if ( compute_size_var )
@@ -307,6 +311,7 @@ void CaseField::GenPubDecls(Output* out_h, Env* env) {
     if ( ! index_ )
         out_h->println("return %s;", lvalue());
     else {
+        out_h->println("// NOLINTBEGIN(bugprone-branch-clone)");
         out_h->println("switch ( %s ) {", env->RValue(index_var_));
         out_h->inc_indent();
         GenCaseStr(index_, out_h, env, case_type()->IndexExpr()->DataType(env));
@@ -323,6 +328,7 @@ void CaseField::GenPubDecls(Output* out_h, Env* env) {
 
         out_h->dec_indent();
         out_h->println("}");
+        out_h->println("// NOLINTEND(bugprone-branch-clone)");
 
         out_h->println("return %s;", lvalue());
     }
diff --git a/tools/binpac/src/pac_expr.cc b/tools/binpac/src/pac_expr.cc
index 4f74859f72..fca87cff66 100644
--- a/tools/binpac/src/pac_expr.cc
+++ b/tools/binpac/src/pac_expr.cc
@@ -209,6 +209,7 @@ void Expr::GenCaseEval(Output* out_cc, Env* env) {
     foreach (i, CaseExprList, cases_)
         (*i)->value()->ForceIDEval(out_cc, env);
 
+    out_cc->println("// NOLINTBEGIN(bugprone-branch-clone)");
     out_cc->println("switch ( %s ) {", operand_[0]->EvalExpr(out_cc, env));
     Type* switch_type = operand_[0]->DataType(env);
 
@@ -247,6 +248,7 @@ void Expr::GenCaseEval(Output* out_cc, Env* env) {
 
     out_cc->dec_indent();
     out_cc->println("}");
+    out_cc->println("// NOLINTEND(bugprone-branch-clone)");
 
     env->SetEvaluated(val_var);
     str_ = env->RValue(val_var);
diff --git a/tools/binpac/src/pac_record.cc b/tools/binpac/src/pac_record.cc
index a65074751c..145604b13a 100644
--- a/tools/binpac/src/pac_record.cc
+++ b/tools/binpac/src/pac_record.cc
@@ -100,6 +100,7 @@ void RecordType::DoGenParseCode(Output* out_cc, Env* env, const DataPtr& data, i
         GenBoundaryCheck(out_cc, env, data);
 
     if ( incremental_parsing() ) {
+        out_cc->println("// NOLINTBEGIN(bugprone-branch-clone)");
         out_cc->println("switch ( %s ) {", env->LValue(parsing_state_id));
 
         out_cc->println("case 0:");
@@ -113,6 +114,7 @@ void RecordType::DoGenParseCode(Output* out_cc, Env* env, const DataPtr& data, i
         out_cc->println("%s = true;", env->LValue(parsing_complete_var()));
         out_cc->dec_indent();
         out_cc->println("}");
+        out_cc->println("// NOLINTEND(bugprone-branch-clone)");
     }
     else {
         ASSERT(data.id() == begin_of_data && data.offset() == 0);
diff --git a/tools/binpac/src/pac_type.cc b/tools/binpac/src/pac_type.cc
index 9ea73fd339..7a66f65a87 100644
--- a/tools/binpac/src/pac_type.cc
+++ b/tools/binpac/src/pac_type.cc
@@ -487,6 +487,7 @@ void Type::GenParseBuffer(Output* out_cc, Env* env, int flags) {
 
     if ( attr_length_expr() ) {
         ASSERT(buffer_mode() == BUFFER_BY_LENGTH);
+        out_cc->println("// NOLINTBEGIN(bugprone-branch-clone)");
         out_cc->println("switch ( %s ) {", env->LValue(buffering_state_id));
         out_cc->inc_indent();
         out_cc->println("case 0:");
@@ -537,6 +538,7 @@ void Type::GenParseBuffer(Output* out_cc, Env* env, int flags) {
         out_cc->dec_indent();
         out_cc->dec_indent();
         out_cc->println("}");
+        out_cc->println("// NOLINTEND(bugprone-branch-clone)");
     }
     else if ( attr_restofflow_ ) {
         out_cc->println("BINPAC_ASSERT(%s->eof());", env->RValue(flow_buffer_id));