[clang] [Clang][Sema] Check the number of lambda non-concept tempate parameters (PR #74885)

[via cfe-commits]

https://github.com/knightXun created https://github.com/llvm/llvm-project/pull/74885

Check that the number of non-concept template parameters is greater than zero during lambda template instantiation to aviod panic Fix issue: https://github.com/llvm/llvm-project/issues/70601

>From 05588ae4cd3e0a55f946c9d109470afbfd91c1be Mon Sep 17 00:00:00 2001
From: knightXun <badgangkiller at gmail.com>
Date: Sat, 9 Dec 2023 04:57:15 +0800
Subject: [PATCH] [Clang][Sema] Check the number of lambda non-concept tempate
 parameters Check that the number of non-concept template parameters is
 greater than zero during lambda template instantiation to aviod panic Fix
 issue: https://github.com/llvm/llvm-project/issues/70601

---
 clang/include/clang/Basic/DiagnosticParseKinds.td |  2 ++
 clang/lib/Sema/TreeTransform.h                    | 14 ++++++++++++++
 2 files changed, 16 insertions(+)

diff --git a/clang/include/clang/Basic/DiagnosticParseKinds.td b/clang/include/clang/Basic/DiagnosticParseKinds.td
index 6150fc36430ab..e46fa69d013b6 100644
--- a/clang/include/clang/Basic/DiagnosticParseKinds.td
+++ b/clang/include/clang/Basic/DiagnosticParseKinds.td
@@ -851,6 +851,8 @@ def err_friend_explicit_instantiation : Error<
 def err_explicit_instantiation_enum : Error<
   "enumerations cannot be explicitly instantiated">;
 def err_expected_template_parameter : Error<"expected template parameter">;
+def err_expected_non_concept_template_parameter : Error<
+  "expected non-concept template parameter">;
 def err_empty_requires_expr : Error<
   "a requires expression must contain at least one requirement">;
 def err_requires_expr_parameter_list_ellipsis : Error<
diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h
index 1ad843d0bf4e0..110024a377128 100644
--- a/clang/lib/Sema/TreeTransform.h
+++ b/clang/lib/Sema/TreeTransform.h
@@ -13594,6 +13594,20 @@ TreeTransform<Derived>::TransformLambdaExpr(LambdaExpr *E) {
     getSema().AddTemplateParametersToLambdaCallOperator(NewCallOperator, Class,
                                                         TPL);
 
+  // Check the number of the Concept template parameters
+  size_t conceptParams = 0;
+  for (auto P : *E->getTemplateParameterList()) {
+    const TemplateTypeParmDecl *CD = dyn_cast<TemplateTypeParmDecl>(P);
+    if (CD && CD->hasTypeConstraint()) {
+      conceptParams++;
+    }
+  }
+
+  if (conceptParams == E->getTemplateParameterList()->size()) {
+    getSema().Diag(E->getTemplateParameterList()->getLAngleLoc(),
+                   diag::err_expected_non_concept_template_parameter);
+    return ExprError();
+  }
   // Transform the type of the original lambda's call operator.
   // The transformation MUST be done in the CurrentInstantiationScope since
   // it introduces a mapping of the original to the newly created