[Clang][Sema] Check the number of lambda non-concept tempate parameters

[knightXun]

Check that the number of non-concept template parameters is greater than zero during lambda template instantiation to aviod panic Fix issue: #70601

[llvmbot]

@llvm/pr-subscribers-clang

Author: flyingcat (knightXun)

Changes

Check that the number of non-concept template parameters is greater than zero during lambda template instantiation to aviod panic Fix issue: #70601

---

Full diff: https://github.com/llvm/llvm-project/pull/74885.diff

2 Files Affected:

• (modified) clang/include/clang/Basic/DiagnosticParseKinds.td (+2)
• (modified) clang/lib/Sema/TreeTransform.h (+14)

diff --git a/clang/include/clang/Basic/DiagnosticParseKinds.td b/clang/include/clang/Basic/DiagnosticParseKinds.td
index 6150fc36430ab1..e46fa69d013b61 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 1ad843d0bf4e0c..110024a377128b 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

[shafik]

This needs at least one test and a Release note.

I expect the code form the issue to be well-formed: https://godbolt.org/z/bhdfG34xc

So I am curious why you are adding the diagnostic for?

[knightXun]

This needs at least one test and a Release note.

I expect the code form the issue to be well-formed: https://godbolt.org/z/bhdfG34xc

So I am curious why you are adding the diagnostic for?

thanks for the hit!

[github-actions]

⚠️ C/C++ code formatter, clang-format found issues in your code. ⚠️

You can test this locally with the following command:

git-clang-format --diff 44dc1e0baae7c4b8a02ba06dcf396d3d452aa873 c3eecf5b35da2acb44bc06d2e6663222c18c867f -- clang/lib/Sema/SemaConcept.cpp clang/lib/Sema/SemaTemplateDeduction.cpp clang/lib/Sema/TreeTransform.h

View the diff from clang-format here.

diff --git a/clang/lib/Sema/SemaTemplateDeduction.cpp b/clang/lib/Sema/SemaTemplateDeduction.cpp
index 954ca488a0..20e7ea3dcc 100644
--- a/clang/lib/Sema/SemaTemplateDeduction.cpp
+++ b/clang/lib/Sema/SemaTemplateDeduction.cpp
@@ -4352,17 +4352,17 @@ Sema::TemplateDeductionResult Sema::DeduceTemplateArguments(
   const auto *Proto = Function->getType()->castAs<FunctionProtoType>();
   if (!Proto->isTemplateVariadic()) {
     size_t params = 0, deducedParams = 0;
-    for(auto P : *TemplateParams) {
+    for (auto P : *TemplateParams) {
       const TemplateTypeParmDecl *CD = dyn_cast<TemplateTypeParmDecl>(P);
-      if(CD && CD->hasTypeConstraint()) {
+      if (CD && CD->hasTypeConstraint()) {
         params++;
       }
     }
-    for( auto P : Deduced ) {
+    for (auto P : Deduced) {
       deducedParams++;
     }
 
-    if( params > deducedParams ) {
+    if (params > deducedParams) {
       return TDK_Invalid;
     }
   }