[OpenMP] Context selector extensions for template functions

[jdoerfert]

Summary

With this extension the effects of omp begin declare variant will be
applied to template function declarations. The behavior is opt-in and
controlled by the extension(allow_templates) trait. While generally
useful, this will enable us to implement complex math function calls by
overloading the templates of the standard library with the ones in
libc++.

[JonChesterfield]

Nice. What makes it an extension? 5.0 / 2.3.5 claims "and where variant-func-id is the name of a function variant that is either a base language identifier or, for C++, a template-id." which suggests this could be always-on

clang/lib/Sema/SemaOpenMP.cpp

5871

tabs!

[jdoerfert]

In D85735#2210662, @JonChesterfield wrote:

Nice. What makes it an extension? 5.0 / 2.3.5 claims "and where variant-func-id is the name of a function variant that is either a base language identifier or, for C++, a template-id." which suggests this could be always-on

This is for begin/end declare variant, a 5.1 feature. There it says:

The begin declare variant directive associates the context selector in the match clause with each function definition in declaration-definition-seq.

So it applies to function definitions between the begin and end. With the extension it applies to template function definitions too.

[jdoerfert]

Rebase on top of D85878

[jdoerfert]

Test formatting

[JonChesterfield]

This looks good to me. I can't claim to have read the test case in detail. Some style suggestions inline around the vector, but they're not blocking.

clang/include/clang/Sema/Sema.h

10042

SmallVectorImpl => SmallVector?

clang/lib/Sema/SemaOpenMP.cpp

5826–5831

Return SmallVector<FunctionDecl> by value instead of via the reference? Makes it clear that we aren't adding to an existing vector

5871

This turned out to be how phabricator represents changes in indent. Unfortunate that the symbol is the one I usually see used for tabs.

clang/test/AST/ast-dump-openmp-begin-declare-variant_template_2.cpp

58

I'd like a different way for us to test this stuff. Realistically impossible to spot errors in 200 lines of tree. Don't have a suggestion at this time.

[ABataev]

clang/include/clang/Sema/Sema.h

10042

It is a good practice to pass SmallVectors as SmallVectorImpl to make it independent of concrete SmallVector template specialization.

[jdoerfert]

clang/include/clang/Sema/Sema.h

10042

We usually use the Impl versions for the APIs to avoid hardcoding the "size" everywhere.

clang/lib/Sema/SemaOpenMP.cpp

5826–5831

Hm, I guess we can do that, it will cause some more copies. FWIW, we are adding to an existing vector if bases is not empty. I mean, if you provide an empty vector we add and if there is something in the vector we add.

clang/test/AST/ast-dump-openmp-begin-declare-variant_template_2.cpp

58

I manually checked it, and now we can verify changes. At the end of the day checking this by hand is actually not too bad. The trick is that you can skip most of it. You go to the test function return value at the very end. Each call expression there should call a function that returns 0. So follow the callee and check the return there (nothing else anyway). I used this scheme for all tests and once you did verify one it is really easy to do the others. Assuming my input is proper ;)

clang/include/clang/Basic/AttrDocs.td

 ``implementation={extension(EXTENSION)}``:
 
   .. code-block:: none
 
     match_all
     match_any
     match_none
     disable_implicit_base
+    allow_templates
 
 The match extensions change when the *entire* context selector is considered a
 match for an OpenMP context. The default is ``all``, with ``none`` no trait in the
 selector is allowed to be in the OpenMP context, with ``any`` a single trait in
 both the selector and OpenMP context is sufficient. Only a single match
 extension trait is allowed per context selector.
 The disable extensions remove default effects of the ``begin declare variant``
 applied to a definition. If ``disable_implicit_base`` is given, we will not
 introduce an implicit base function for a variant if no base function was
 found. The variant is still generated but will never be called, due to the
 absence of a base function and consequently calls to a base function.
+The allow extensions change when the ``begin declare variant`` effect is
+applied to a definition. If ``allow_templates`` is given, template function
+definitions are considered as specializations of existing or assumed template
+declarations with the same name. The template parameters for the base functions
+are used to instantiate the specialization.
 
   }];
 }
 
 def NoStackProtectorDocs : Documentation {
   let Category = DocCatFunction;
   let Content = [{
 Clang supports the ``__attribute__((no_stack_protector))`` attribute which disables

clang/include/clang/Sema/Sema.h

private:
   }
 
   /// The current `omp begin/end declare variant` scopes.
   SmallVector<OMPDeclareVariantScope, 4> OMPDeclareVariantScopes;
 
   /// The declarator \p D defines a function in the scope \p S which is nested
   /// in an `omp begin/end declare variant` scope. In this method we create a
   /// declaration for \p D and rename \p D according to the OpenMP context
-  /// selector of the surrounding scope.
-  FunctionDecl *
-  ActOnStartOfFunctionDefinitionInOpenMPDeclareVariantScope(Scope *S,
-                                                            Declarator &D);
+  /// selector of the surrounding scope. Return all base functions in \p Bases.
+  void ActOnStartOfFunctionDefinitionInOpenMPDeclareVariantScope(
+      Scope *S, Declarator &D, MultiTemplateParamsArg TemplateParameterLists,
+      SmallVectorImpl<FunctionDecl *> &Bases);
 
-  /// Register \p FD as specialization of \p BaseFD in the current `omp
-  /// begin/end declare variant` scope.
+  /// Register \p D as specialization of all base functions in \p Bases in the
+  /// current `omp begin/end declare variant` scope.
   void ActOnFinishedFunctionDefinitionInOpenMPDeclareVariantScope(
-      FunctionDecl *FD, FunctionDecl *BaseFD);
+      Decl *D, SmallVectorImpl<FunctionDecl *> &Bases);
 
 public:
 
   /// Can we exit a scope at the moment.
   bool isInOpenMPDeclareVariantScope() {
     return !OMPDeclareVariantScopes.empty();
   }
 

clang/lib/Headers/openmp_wrappers/cmath

 // Make sure we include our math.h overlay, it probably happend already but we
 // need to be sure.
 #include <math.h>
 
 // We (might) need cstdlib because __clang_cuda_cmath.h below declares `abs`
 // which might live in cstdlib.
 #include <cstdlib>
 
+// We need limits because __clang_cuda_cmath.h below uses `std::numeric_limit`.
+#include <limits>
+
 #pragma omp begin declare variant match(                                       \
-    device = {arch(nvptx, nvptx64)}, implementation = {extension(match_any)})
+    device = {arch(nvptx, nvptx64)}, implementation = {extension(match_any, allow_templates)})
 
 #define __CUDA__
 #define __OPENMP_NVPTX__
 #include <__clang_cuda_cmath.h>
 #undef __OPENMP_NVPTX__
 #undef __CUDA__
 
 // Overloads not provided by the CUDA wrappers but by the CUDA system headers.

clang/lib/Parse/ParseOpenMP.cpp

assert(TISelector.Kind ==
          "`implementation={extension(PROPERTY)}`");
   if (TIProperty.Kind == TraitProperty::invalid)
     return false;
 
   if (TIProperty.Kind ==
       TraitProperty::implementation_extension_disable_implicit_base)
     return true;
 
+  if (TIProperty.Kind ==
+      TraitProperty::implementation_extension_allow_templates)
+    return true;
+
   auto IsMatchExtension = [](OMPTraitProperty &TP) {
     return (TP.Kind ==
                 llvm::omp::TraitProperty::implementation_extension_match_all ||
             TP.Kind ==
                 llvm::omp::TraitProperty::implementation_extension_match_any ||
             TP.Kind ==
                 llvm::omp::TraitProperty::implementation_extension_match_none);
   };

clang/lib/Sema/SemaDecl.cpp

Sema::ActOnStartOfFunctionDef(Scope *FnBodyScope, Declarator &D,
 
   // Check if we are in an `omp begin/end declare variant` scope. If we are, and
   // we define a non-templated function definition, we will create a declaration
   // instead (=BaseFD), and emit the definition with a mangled name afterwards.
   // The base function declaration will have the equivalent of an `omp declare
   // variant` annotation which specifies the mangled definition as a
   // specialization function under the OpenMP context defined as part of the
   // `omp begin declare variant`.
-  FunctionDecl *BaseFD = nullptr;
-  if (LangOpts.OpenMP && isInOpenMPDeclareVariantScope() &&
-      TemplateParameterLists.empty())
-    BaseFD = ActOnStartOfFunctionDefinitionInOpenMPDeclareVariantScope(
-        ParentScope, D);
+  SmallVector<FunctionDecl *, 4> Bases;
+  if (LangOpts.OpenMP && isInOpenMPDeclareVariantScope())
+    ActOnStartOfFunctionDefinitionInOpenMPDeclareVariantScope(
+        ParentScope, D, TemplateParameterLists, Bases);
 
   D.setFunctionDefinitionKind(FDK_Definition);
   Decl *DP = HandleDeclarator(ParentScope, D, TemplateParameterLists);
   Decl *Dcl = ActOnStartOfFunctionDef(FnBodyScope, DP, SkipBody);
 
-  if (BaseFD)
-    ActOnFinishedFunctionDefinitionInOpenMPDeclareVariantScope(
-        cast<FunctionDecl>(Dcl), BaseFD);
+  if (!Bases.empty())
+    ActOnFinishedFunctionDefinitionInOpenMPDeclareVariantScope(Dcl, Bases);
 
   return Dcl;
 }
 
 void Sema::ActOnFinishInlineFunctionDef(FunctionDecl *D) {
   Consumer.HandleInlineFunctionDefinition(D);
 }
 

clang/lib/Sema/SemaOpenMP.cpp

static void setPrototype(Sema &S, FunctionDecl *FD, FunctionDecl *FDWithProto,
   }
 
   FD->setParams(Params);
 }
 
 Sema::OMPDeclareVariantScope::OMPDeclareVariantScope(OMPTraitInfo &TI)
     : TI(&TI), NameSuffix(TI.getMangledName()) {}
 
-FunctionDecl *
-Sema::ActOnStartOfFunctionDefinitionInOpenMPDeclareVariantScope(Scope *S,
-                                                                Declarator &D) {
+void Sema::ActOnStartOfFunctionDefinitionInOpenMPDeclareVariantScope(
+    Scope *S, Declarator &D, MultiTemplateParamsArg TemplateParamLists,
+    SmallVectorImpl<FunctionDecl *> &Bases) {
+  if (!D.getIdentifier())
+    return;
+
   OMPDeclareVariantScope &DVScope = OMPDeclareVariantScopes.back();
+
+  // Template specialization is an extension, check if we do it.
+  bool IsTemplated = !TemplateParamLists.empty();
+  if (IsTemplated &
+      !DVScope.TI->isExtensionActive(
+          llvm::omp::TraitProperty::implementation_extension_allow_templates))
+    return;
+
   IdentifierInfo *BaseII = D.getIdentifier();
   LookupResult Lookup(*this, DeclarationName(BaseII), D.getIdentifierLoc(),
                       LookupOrdinaryName);
   LookupParsedName(Lookup, S, &D.getCXXScopeSpec());
 
   TypeSourceInfo *TInfo = GetTypeForDeclarator(D, S);
   QualType FType = TInfo->getType();
 
   bool IsConstexpr = D.getDeclSpec().getConstexprSpecifier() == CSK_constexpr;
   bool IsConsteval = D.getDeclSpec().getConstexprSpecifier() == CSK_consteval;
 
-  FunctionDecl *BaseFD = nullptr;
   for (auto *Candidate : Lookup) {
-    auto *UDecl = dyn_cast<FunctionDecl>(Candidate->getUnderlyingDecl());
+    auto *CandidateDecl = Candidate->getUnderlyingDecl();
+    FunctionDecl *UDecl = nullptr;
+    if (IsTemplated && isa<FunctionTemplateDecl>(CandidateDecl))
+      UDecl = cast<FunctionTemplateDecl>(CandidateDecl)->getTemplatedDecl();
+    else if (!IsTemplated)
+      UDecl = dyn_cast<FunctionDecl>(CandidateDecl);
     if (!UDecl)
       continue;
 
     // Don't specialize constexpr/consteval functions with
     // non-constexpr/consteval functions.
     if (UDecl->isConstexpr() && !IsConstexpr)
       continue;
     if (UDecl->isConsteval() && !IsConsteval)
       continue;
 
+    QualType UDeclTy = UDecl->getType();
+    // TODO: Verify types for templates eventually.
+    if (!UDeclTy->isDependentType()) {
       QualType NewType = Context.mergeFunctionTypes(
-        FType, UDecl->getType(), /* OfBlockPointer */ false,
+          FType, UDeclTy, /* OfBlockPointer */ false,
           /* Unqualified */ false, /* AllowCXX */ true);
       if (NewType.isNull())
         continue;
+    }
 
     // Found a base!
-    BaseFD = UDecl;
-    break;
+    Bases.push_back(UDecl);
   }
-  if (!BaseFD && !DVScope.TI->isExtensionActive(
-                     llvm::omp::TraitProperty::
-                         implementation_extension_disable_implicit_base)) {
-    BaseFD = cast<FunctionDecl>(ActOnDeclarator(S, D));
-    BaseFD->setImplicit(true);
+
+  // IF no base was found we create a declaration that we use as base.
+  if (Bases.empty() &&
+      !DVScope.TI->isExtensionActive(
+    D.setFunctionDefinitionKind(FDK_Declaration);
+    Decl *BaseD = HandleDeclarator(S, D, TemplateParamLists);
+    BaseD->setImplicit(true);
+    if (auto *BaseTemplD = dyn_cast<FunctionTemplateDecl>(BaseD))
+      Bases.push_back(BaseTemplD->getTemplatedDecl());
+    else
+      Bases.push_back(cast<FunctionDecl>(BaseD));
   }
 
   std::string MangledName;
   MangledName += D.getIdentifier()->getName();
   MangledName += getOpenMPVariantManglingSeparatorStr();
   MangledName += DVScope.NameSuffix;
   IdentifierInfo &VariantII = Context.Idents.get(MangledName);
 
   VariantII.setMangledOpenMPVariantName(true);
   D.SetIdentifier(&VariantII, D.getBeginLoc());
-  return BaseFD;
 }
 
 void Sema::ActOnFinishedFunctionDefinitionInOpenMPDeclareVariantScope(
-    FunctionDecl *FD, FunctionDecl *BaseFD) {
+    Decl *D, SmallVectorImpl<FunctionDecl *> &Bases) {
   // Do not mark function as is used to prevent its emission if this is the
   // only place where it is used.
   EnterExpressionEvaluationContext Unevaluated(
       *this, Sema::ExpressionEvaluationContext::Unevaluated);
 
-  Expr *VariantFuncRef = DeclRefExpr::Create(
+  FunctionDecl *FD = nullptr;
+  if (auto *UTemplDecl = dyn_cast<FunctionTemplateDecl>(D))
+    FD = UTemplDecl->getTemplatedDecl();
+  else
+    FD = cast<FunctionDecl>(D);
+  auto *VariantFuncRef = DeclRefExpr::Create(
       Context, NestedNameSpecifierLoc(), SourceLocation(), FD,
       /* RefersToEnclosingVariableOrCapture */ false,
       /* NameLoc */ FD->getLocation(), FD->getType(), ExprValueKind::VK_RValue);
 
   OMPDeclareVariantScope &DVScope = OMPDeclareVariantScopes.back();
   auto *OMPDeclareVariantA = OMPDeclareVariantAttr::CreateImplicit(
       Context, VariantFuncRef, DVScope.TI);
+  for (FunctionDecl *BaseFD : Bases)
     BaseFD->addAttr(OMPDeclareVariantA);
 }
 
 ExprResult Sema::ActOnOpenMPCall(ExprResult Call, Scope *Scope,
                                  SourceLocation LParenLoc,
                                  MultiExprArg ArgExprs,
                                  SourceLocation RParenLoc, Expr *ExecConfig) {
   // The common case is a regular call we do not want to specialize at all. Try
   // to make that case fast by bailing early.
auto HandleNonConstantScoresAndConditions = [this](Expr *&E,
     }
     return true;
   };
   if (TI.anyScoreOrCondition(HandleNonConstantScoresAndConditions))
     return None;
 
   // Convert VariantRef expression to the type of the original function to
   // resolve possible conflicts.
-  ExprResult VariantRefCast;
+  ExprResult VariantRefCast = VariantRef;
   if (LangOpts.CPlusPlus) {
     QualType FnPtrType;
     auto *Method = dyn_cast<CXXMethodDecl>(FD);
     if (Method && !Method->isStatic()) {
       const Type *ClassType =
           Context.getTypeDeclType(Method->getParent()).getTypePtr();
       FnPtrType = Context.getMemberPointerType(FD->getType(), ClassType);
       ExprResult ER;
       {
         // Build adrr_of unary op to correctly handle type checks for member
         // functions.
         Sema::TentativeAnalysisScope Trap(*this);
         ER = CreateBuiltinUnaryOp(VariantRef->getBeginLoc(), UO_AddrOf,
                                   VariantRef);
       }
       if (!ER.isUsable()) {
         Diag(VariantRef->getExprLoc(), diag::err_omp_function_expected)
             << VariantId << VariantRef->getSourceRange();
         return None;
       }
       VariantRef = ER.get();
     } else {
       FnPtrType = Context.getPointerType(FD->getType());
     }
-    ImplicitConversionSequence ICS =
-        TryImplicitConversion(VariantRef, FnPtrType.getUnqualifiedType(),
-                              /*SuppressUserConversions=*/false,
-                              AllowedExplicit::None,
-                              /*InOverloadResolution=*/false,
-                              /*CStyle=*/false,
-                              /*AllowObjCWritebackConversion=*/false);
+    QualType VarianPtrType = Context.getPointerType(VariantRef->getType());
+    if (VarianPtrType.getUnqualifiedType() != FnPtrType.getUnqualifiedType()) {
+      ImplicitConversionSequence ICS = TryImplicitConversion(
+          VariantRef, FnPtrType.getUnqualifiedType(),
+          /*SuppressUserConversions=*/false, AllowedExplicit::None,
       if (ICS.isFailure()) {
         Diag(VariantRef->getExprLoc(),
              diag::err_omp_declare_variant_incompat_types)
             << VariantRef->getType()
             << ((Method && !Method->isStatic()) ? FnPtrType : FD->getType())
             << VariantRef->getSourceRange();
         return None;
       }
       VariantRefCast = PerformImplicitConversion(
           VariantRef, FnPtrType.getUnqualifiedType(), AA_Converting);
       if (!VariantRefCast.isUsable())
         return None;
+    }
     // Drop previously built artificial addr_of unary op for member functions.
     if (Method && !Method->isStatic()) {
       Expr *PossibleAddrOfVariantRef = VariantRefCast.get();
       if (auto *UO = dyn_cast<UnaryOperator>(
               PossibleAddrOfVariantRef->IgnoreImplicit()))
         VariantRefCast = UO->getSubExpr();
     }
-  } else {
-    VariantRefCast = VariantRef;
   }
 
   ExprResult ER = CheckPlaceholderExpr(VariantRefCast.get());
   if (!ER.isUsable() ||
       !ER.get()->IgnoreParenImpCasts()->getType()->isFunctionType()) {
     Diag(VariantRef->getExprLoc(), diag::err_omp_function_expected)
         << VariantId << VariantRef->getSourceRange();
     return None;

clang/lib/Sema/SemaTemplateInstantiateDecl.cpp

if (E) {
       else
         return true;
     }
     return false;
   };
   if (TI.anyScoreOrCondition(SubstScoreOrConditionExpr))
     return;
 
-  // Check function/variant ref.
+  Expr *E = VariantFuncRef.get();
+  // Check function/variant ref for `omp declare variant` but not for `omp
+  // begin declare variant` (which use implicit attributes).
   Optional<std::pair<FunctionDecl *, Expr *>> DeclVarData =
       S.checkOpenMPDeclareVariantFunction(S.ConvertDeclToDeclGroup(New),
                                           VariantFuncRef.get(), TI,
                                           Attr.getRange());
 
   if (!DeclVarData)
     return;
 
-  S.ActOnOpenMPDeclareVariantDirective(DeclVarData.getValue().first,
-                                       DeclVarData.getValue().second, TI,
-                                       Attr.getRange());
+  E = DeclVarData.getValue().second;
+  FD = DeclVarData.getValue().first;
+
+  if (auto *VariantDRE = dyn_cast<DeclRefExpr>(E->IgnoreParenImpCasts())) {
+    if (auto *VariantFD = dyn_cast<FunctionDecl>(VariantDRE->getDecl())) {
+      if (auto *VariantFTD = VariantFD->getDescribedFunctionTemplate()) {
+        if (!VariantFTD->isThisDeclarationADefinition())
+          return;
+        Sema::TentativeAnalysisScope Trap(S);
+        const TemplateArgumentList *TAL = TemplateArgumentList::CreateCopy(
+            S.Context, TemplateArgs.getInnermost());
+
+        auto *SubstFD = S.InstantiateFunctionDeclaration(VariantFTD, TAL,
+                                                         New->getLocation());
+        if (!SubstFD)
+          return;
+        S.InstantiateFunctionDefinition(
+            New->getLocation(), SubstFD, /* Recursive */ true,
+            /* DefinitionRequired */ false, /* AtEndOfTU */ false);
+        SubstFD->setInstantiationIsPending(!SubstFD->isDefined());
+        E = DeclRefExpr::Create(S.Context, NestedNameSpecifierLoc(),
+                                SourceLocation(), SubstFD,
+                                /* RefersToEnclosingVariableOrCapture */ false,
+                                /* NameLoc */ SubstFD->getLocation(),
+                                SubstFD->getType(), ExprValueKind::VK_RValue);
+      }
+    }
+  }
+
+  S.ActOnOpenMPDeclareVariantDirective(FD, E, TI, Attr.getRange());
 }
 
 static void instantiateDependentAMDGPUFlatWorkGroupSizeAttr(
     Sema &S, const MultiLevelTemplateArgumentList &TemplateArgs,
     const AMDGPUFlatWorkGroupSizeAttr &Attr, Decl *New) {
   // Both min and max expression are constant expressions.
   EnterExpressionEvaluationContext Unevaluated(
       S, Sema::ExpressionEvaluationContext::ConstantEvaluated);

clang/test/AST/ast-dump-openmp-begin-declare-variant_template_2.cpp

+// RUN: %clang_cc1 -triple x86_64-unknown-unknown -fopenmp -verify -ast-dump %s -x c++ | FileCheck %s
+// expected-no-diagnostics
+
+template <typename T>
+int also_before(T) {
+  return 1;
+}
+template <int V>
+int also_before_mismatch(void) {
+  return 0;
+}
+int also_before_non_template(void) {
+  return 0;
+}
+
+#pragma omp begin declare variant match(implementation = {extension(allow_templates)})
+template <typename T>
+int also_before(T) {
+  return 0;
+}
+template <typename T>
+int also_after(T) {
+  return 0;
+}
+template <typename T, typename Q>
+int also_after_mismatch(T, Q) {
+  return 2;
+}
+template <typename T>
+int also_before_mismatch(T) {
+  return 3;
+}
+template <typename T>
+int also_before_non_template(T) {
+  return 4;
+}
+template <int V>
+int only_def(void) {
+  return 0;
+}
+#pragma omp end declare variant
+
+template <typename T>
+int also_after(T) {
+  return 6;
+}
+template <typename T>
+int also_after_mismatch(T) {
+  return 0;
+}
+
+int test() {
+  // Should return 0.
+  return also_before(0.) + also_before_mismatch<0>() + also_before_non_template() + also_after<char>(0) + also_after_mismatch(0) + only_def<0>();
+}
+
+// CHECK:      |-FunctionTemplateDecl [[ADDR_0:0x[a-z0-9]*]] <{{.*}}, line:7:1> line:5:5 also_before
+// CHECK-NEXT: | |-TemplateTypeParmDecl [[ADDR_1:0x[a-z0-9]*]] <line:4:10, col:19> col:19 referenced typename depth 0 index 0 T
+// CHECK-NEXT: | |-FunctionDecl [[ADDR_2:0x[a-z0-9]*]] <line:5:1, line:7:1> line:5:5 also_before 'int (T)'
+// CHECK-NEXT: | | |-ParmVarDecl [[ADDR_3:0x[a-z0-9]*]] <col:17> col:18 'T'
+// CHECK-NEXT: | | |-CompoundStmt [[ADDR_4:0x[a-z0-9]*]] <col:20, line:7:1>
+// CHECK-NEXT: | | | `-ReturnStmt [[ADDR_5:0x[a-z0-9]*]] <line:6:3, col:10>
+// CHECK-NEXT: | | |   `-IntegerLiteral [[ADDR_6:0x[a-z0-9]*]] <col:10> 'int' 1
+// CHECK-NEXT: | | `-OMPDeclareVariantAttr [[ADDR_7:0x[a-z0-9]*]] <<invalid sloc>> Implicit implementation={extension(allow_templates)}
+// CHECK-NEXT: | |   `-DeclRefExpr [[ADDR_8:0x[a-z0-9]*]] <line:18:1> 'int (T)' Function [[ADDR_9:0x[a-z0-9]*]] 'also_before[implementation={extension(allow_templates)}]' 'int (T)'
+// CHECK-NEXT: | `-FunctionDecl [[ADDR_10:0x[a-z0-9]*]] <line:5:1, line:7:1> line:5:5 used also_before 'int (double)'
+// CHECK-NEXT: |   |-TemplateArgument type 'double'
+// CHECK-NEXT: |   | `-BuiltinType [[ADDR_11:0x[a-z0-9]*]] 'double'
+// CHECK-NEXT: |   |-ParmVarDecl [[ADDR_12:0x[a-z0-9]*]] <col:17> col:18 'double':'double'
+// CHECK-NEXT: |   |-CompoundStmt [[ADDR_13:0x[a-z0-9]*]] <col:20, line:7:1>
+// CHECK-NEXT: |   | `-ReturnStmt [[ADDR_14:0x[a-z0-9]*]] <line:6:3, col:10>
+// CHECK-NEXT: |   |   `-IntegerLiteral [[ADDR_6]] <col:10> 'int' 1
+// CHECK-NEXT: |   `-OMPDeclareVariantAttr [[ADDR_15:0x[a-z0-9]*]] <<invalid sloc>> Implicit implementation={extension(allow_templates)}
+// CHECK-NEXT: |     `-DeclRefExpr [[ADDR_16:0x[a-z0-9]*]] <line:18:1> 'int (double)' Function [[ADDR_17:0x[a-z0-9]*]] 'also_before[implementation={extension(allow_templates)}]' 'int (double)'
+// CHECK-NEXT: |-FunctionTemplateDecl [[ADDR_18:0x[a-z0-9]*]] <line:8:1, line:11:1> line:9:5 also_before_mismatch
+// CHECK-NEXT: | |-NonTypeTemplateParmDecl [[ADDR_19:0x[a-z0-9]*]] <line:8:10, col:14> col:14 'int' depth 0 index 0 V
+// CHECK-NEXT: | |-FunctionDecl [[ADDR_20:0x[a-z0-9]*]] <line:9:1, line:11:1> line:9:5 also_before_mismatch 'int ({{.*}})'
+// CHECK-NEXT: | | `-CompoundStmt [[ADDR_21:0x[a-z0-9]*]] <col:32, line:11:1>
+// CHECK-NEXT: | |   `-ReturnStmt [[ADDR_22:0x[a-z0-9]*]] <line:10:3, col:10>
+// CHECK-NEXT: | |     `-IntegerLiteral [[ADDR_23:0x[a-z0-9]*]] <col:10> 'int' 0
+// CHECK-NEXT: | `-FunctionDecl [[ADDR_24:0x[a-z0-9]*]] <line:9:1, line:11:1> line:9:5 used also_before_mismatch 'int ({{.*}})'
+// CHECK-NEXT: |   |-TemplateArgument integral 0
+// CHECK-NEXT: |   `-CompoundStmt [[ADDR_25:0x[a-z0-9]*]] <col:32, line:11:1>
+// CHECK-NEXT: |     `-ReturnStmt [[ADDR_26:0x[a-z0-9]*]] <line:10:3, col:10>
+// CHECK-NEXT: |       `-IntegerLiteral [[ADDR_23]] <col:10> 'int' 0
+// CHECK-NEXT: |-FunctionDecl [[ADDR_27:0x[a-z0-9]*]] <line:12:1, line:14:1> line:12:5 used also_before_non_template 'int ({{.*}})'
+// CHECK-NEXT: | `-CompoundStmt [[ADDR_28:0x[a-z0-9]*]] <col:36, line:14:1>
+// CHECK-NEXT: |   `-ReturnStmt [[ADDR_29:0x[a-z0-9]*]] <line:13:3, col:10>
+// CHECK-NEXT: |     `-IntegerLiteral [[ADDR_30:0x[a-z0-9]*]] <col:10> 'int' 0
+// CHECK-NEXT: |-FunctionTemplateDecl [[ADDR_31:0x[a-z0-9]*]] <line:17:1, line:20:1> line:18:1 also_before[implementation={extension(allow_templates)}]
+// CHECK-NEXT: | |-TemplateTypeParmDecl [[ADDR_32:0x[a-z0-9]*]] <line:17:10, col:19> col:19 referenced typename depth 0 index 0 T
+// CHECK-NEXT: | |-FunctionDecl [[ADDR_9]] <line:18:1, line:20:1> line:18:1 referenced also_before[implementation={extension(allow_templates)}] 'int (T)'
+// CHECK-NEXT: | | |-ParmVarDecl [[ADDR_33:0x[a-z0-9]*]] <col:17> col:18 'T'
+// CHECK-NEXT: | | `-CompoundStmt [[ADDR_34:0x[a-z0-9]*]] <col:20, line:20:1>
+// CHECK-NEXT: | |   `-ReturnStmt [[ADDR_35:0x[a-z0-9]*]] <line:19:3, col:10>
+// CHECK-NEXT: | |     `-IntegerLiteral [[ADDR_36:0x[a-z0-9]*]] <col:10> 'int' 0
+// CHECK-NEXT: | `-FunctionDecl [[ADDR_17]] <line:18:1, line:20:1> line:18:1 also_before[implementation={extension(allow_templates)}] 'int (double)'
+// CHECK-NEXT: |   |-TemplateArgument type 'double'
+// CHECK-NEXT: |   | `-BuiltinType [[ADDR_11]] 'double'
+// CHECK-NEXT: |   |-ParmVarDecl [[ADDR_37:0x[a-z0-9]*]] <col:17> col:18 'double':'double'
+// CHECK-NEXT: |   `-CompoundStmt [[ADDR_38:0x[a-z0-9]*]] <col:20, line:20:1>
+// CHECK-NEXT: |     `-ReturnStmt [[ADDR_39:0x[a-z0-9]*]] <line:19:3, col:10>
+// CHECK-NEXT: |       `-IntegerLiteral [[ADDR_36]] <col:10> 'int' 0
+// CHECK-NEXT: |-FunctionTemplateDecl [[ADDR_40:0x[a-z0-9]*]] <line:21:1, line:22:17> col:5 implicit also_after
+// CHECK-NEXT: | |-TemplateTypeParmDecl [[ADDR_41:0x[a-z0-9]*]] <line:21:10, col:19> col:19 referenced typename depth 0 index 0 T
+// CHECK-NEXT: | |-FunctionDecl [[ADDR_42:0x[a-z0-9]*]] <line:22:1, col:17> col:5 also_after 'int (T)'
+// CHECK-NEXT: | | |-ParmVarDecl [[ADDR_43:0x[a-z0-9]*]] <col:16> col:17 'T'
+// CHECK-NEXT: | | `-OMPDeclareVariantAttr [[ADDR_44:0x[a-z0-9]*]] <<invalid sloc>> Implicit implementation={extension(allow_templates)}
+// CHECK-NEXT: | |   `-DeclRefExpr [[ADDR_45:0x[a-z0-9]*]] <col:1> 'int (T)' Function [[ADDR_46:0x[a-z0-9]*]] 'also_after[implementation={extension(allow_templates)}]' 'int (T)'
+// CHECK-NEXT: | `-FunctionDecl [[ADDR_47:0x[a-z0-9]*]] <line:44:1, line:46:1> line:44:5 used also_after 'int (char)'
+// CHECK-NEXT: |   |-TemplateArgument type 'char'
+// CHECK-NEXT: |   | `-BuiltinType [[ADDR_48:0x[a-z0-9]*]] 'char'
+// CHECK-NEXT: |   |-ParmVarDecl [[ADDR_49:0x[a-z0-9]*]] <col:16> col:17 'char':'char'
+// CHECK-NEXT: |   |-CompoundStmt [[ADDR_50:0x[a-z0-9]*]] <col:19, line:46:1>
+// CHECK-NEXT: |   | `-ReturnStmt [[ADDR_51:0x[a-z0-9]*]] <line:45:3, col:10>
+// CHECK-NEXT: |   |   `-IntegerLiteral [[ADDR_52:0x[a-z0-9]*]] <col:10> 'int' 6
+// CHECK-NEXT: |   `-OMPDeclareVariantAttr [[ADDR_53:0x[a-z0-9]*]] <<invalid sloc>> Implicit implementation={extension(allow_templates)}
+// CHECK-NEXT: |     `-DeclRefExpr [[ADDR_54:0x[a-z0-9]*]] <line:22:1> 'int (char)' Function [[ADDR_55:0x[a-z0-9]*]] 'also_after[implementation={extension(allow_templates)}]' 'int (char)'
+// CHECK-NEXT: |-FunctionTemplateDecl [[ADDR_56:0x[a-z0-9]*]] <line:21:1, line:24:1> line:22:1 also_after[implementation={extension(allow_templates)}]
+// CHECK-NEXT: | |-TemplateTypeParmDecl [[ADDR_41]] <line:21:10, col:19> col:19 referenced typename depth 0 index 0 T
+// CHECK-NEXT: | |-FunctionDecl [[ADDR_46]] <line:22:1, line:24:1> line:22:1 referenced also_after[implementation={extension(allow_templates)}] 'int (T)'
+// CHECK-NEXT: | | |-ParmVarDecl [[ADDR_43]] <col:16> col:17 'T'
+// CHECK-NEXT: | | `-CompoundStmt [[ADDR_57:0x[a-z0-9]*]] <col:19, line:24:1>
+// CHECK-NEXT: | |   `-ReturnStmt [[ADDR_58:0x[a-z0-9]*]] <line:23:3, col:10>
+// CHECK-NEXT: | |     `-IntegerLiteral [[ADDR_59:0x[a-z0-9]*]] <col:10> 'int' 0
+// CHECK-NEXT: | `-FunctionDecl [[ADDR_55]] <line:22:1, line:24:1> line:22:1 also_after[implementation={extension(allow_templates)}] 'int (char)'
+// CHECK-NEXT: |   |-TemplateArgument type 'char'
+// CHECK-NEXT: |   | `-BuiltinType [[ADDR_48]] 'char'
+// CHECK-NEXT: |   |-ParmVarDecl [[ADDR_60:0x[a-z0-9]*]] <col:16> col:17 'char':'char'
+// CHECK-NEXT: |   `-CompoundStmt [[ADDR_61:0x[a-z0-9]*]] <col:19, line:24:1>
+// CHECK-NEXT: |     `-ReturnStmt [[ADDR_62:0x[a-z0-9]*]] <line:23:3, col:10>
+// CHECK-NEXT: |       `-IntegerLiteral [[ADDR_59]] <col:10> 'int' 0
+// CHECK-NEXT: |-FunctionTemplateDecl [[ADDR_63:0x[a-z0-9]*]] <line:25:1, line:26:29> col:5 implicit also_after_mismatch
+// CHECK-NEXT: | |-TemplateTypeParmDecl [[ADDR_64:0x[a-z0-9]*]] <line:25:10, col:19> col:19 referenced typename depth 0 index 0 T
+// CHECK-NEXT: | |-TemplateTypeParmDecl [[ADDR_65:0x[a-z0-9]*]] <col:22, col:31> col:31 referenced typename depth 0 index 1 Q
+// CHECK-NEXT: | `-FunctionDecl [[ADDR_66:0x[a-z0-9]*]] <line:26:1, col:29> col:5 also_after_mismatch 'int (T, Q)'
+// CHECK-NEXT: |   |-ParmVarDecl [[ADDR_67:0x[a-z0-9]*]] <col:25> col:26 'T'
+// CHECK-NEXT: |   |-ParmVarDecl [[ADDR_68:0x[a-z0-9]*]] <col:28> col:29 'Q'
+// CHECK-NEXT: |   `-OMPDeclareVariantAttr [[ADDR_69:0x[a-z0-9]*]] <<invalid sloc>> Implicit implementation={extension(allow_templates)}
+// CHECK-NEXT: |     `-DeclRefExpr [[ADDR_70:0x[a-z0-9]*]] <col:1> 'int (T, Q)' Function [[ADDR_71:0x[a-z0-9]*]] 'also_after_mismatch[implementation={extension(allow_templates)}]' 'int (T, Q)'
+// CHECK-NEXT: |-FunctionTemplateDecl [[ADDR_72:0x[a-z0-9]*]] <line:25:1, line:28:1> line:26:1 also_after_mismatch[implementation={extension(allow_templates)}]
+// CHECK-NEXT: | |-TemplateTypeParmDecl [[ADDR_64]] <line:25:10, col:19> col:19 referenced typename depth 0 index 0 T
+// CHECK-NEXT: | |-TemplateTypeParmDecl [[ADDR_65]] <col:22, col:31> col:31 referenced typename depth 0 index 1 Q
+// CHECK-NEXT: | `-FunctionDecl [[ADDR_71]] <line:26:1, line:28:1> line:26:1 also_after_mismatch[implementation={extension(allow_templates)}] 'int (T, Q)'
+// CHECK-NEXT: |   |-ParmVarDecl [[ADDR_67]] <col:25> col:26 'T'
+// CHECK-NEXT: |   |-ParmVarDecl [[ADDR_68]] <col:28> col:29 'Q'
+// CHECK-NEXT: |   `-CompoundStmt [[ADDR_73:0x[a-z0-9]*]] <col:31, line:28:1>
+// CHECK-NEXT: |     `-ReturnStmt [[ADDR_74:0x[a-z0-9]*]] <line:27:3, col:10>
+// CHECK-NEXT: |       `-IntegerLiteral [[ADDR_75:0x[a-z0-9]*]] <col:10> 'int' 2
+// CHECK-NEXT: |-FunctionTemplateDecl [[ADDR_76:0x[a-z0-9]*]] <line:29:1, line:30:27> col:5 implicit also_before_mismatch
+// CHECK-NEXT: | |-TemplateTypeParmDecl [[ADDR_77:0x[a-z0-9]*]] <line:29:10, col:19> col:19 referenced typename depth 0 index 0 T
+// CHECK-NEXT: | `-FunctionDecl [[ADDR_78:0x[a-z0-9]*]] <line:30:1, col:27> col:5 also_before_mismatch 'int (T)'
+// CHECK-NEXT: |   |-ParmVarDecl [[ADDR_79:0x[a-z0-9]*]] <col:26> col:27 'T'
+// CHECK-NEXT: |   `-OMPDeclareVariantAttr [[ADDR_80:0x[a-z0-9]*]] <<invalid sloc>> Implicit implementation={extension(allow_templates)}
+// CHECK-NEXT: |     `-DeclRefExpr [[ADDR_81:0x[a-z0-9]*]] <col:1> 'int (T)' Function [[ADDR_82:0x[a-z0-9]*]] 'also_before_mismatch[implementation={extension(allow_templates)}]' 'int (T)'
+// CHECK-NEXT: |-FunctionTemplateDecl [[ADDR_83:0x[a-z0-9]*]] <line:29:1, line:32:1> line:30:1 also_before_mismatch[implementation={extension(allow_templates)}]
+// CHECK-NEXT: | |-TemplateTypeParmDecl [[ADDR_77]] <line:29:10, col:19> col:19 referenced typename depth 0 index 0 T
+// CHECK-NEXT: | `-FunctionDecl [[ADDR_82]] <line:30:1, line:32:1> line:30:1 also_before_mismatch[implementation={extension(allow_templates)}] 'int (T)'
+// CHECK-NEXT: |   |-ParmVarDecl [[ADDR_79]] <col:26> col:27 'T'
+// CHECK-NEXT: |   `-CompoundStmt [[ADDR_84:0x[a-z0-9]*]] <col:29, line:32:1>
+// CHECK-NEXT: |     `-ReturnStmt [[ADDR_85:0x[a-z0-9]*]] <line:31:3, col:10>
+// CHECK-NEXT: |       `-IntegerLiteral [[ADDR_86:0x[a-z0-9]*]] <col:10> 'int' 3
+// CHECK-NEXT: |-FunctionTemplateDecl [[ADDR_87:0x[a-z0-9]*]] <line:33:1, line:34:31> col:5 implicit also_before_non_template
+// CHECK-NEXT: | |-TemplateTypeParmDecl [[ADDR_88:0x[a-z0-9]*]] <line:33:10, col:19> col:19 referenced typename depth 0 index 0 T
+// CHECK-NEXT: | `-FunctionDecl [[ADDR_89:0x[a-z0-9]*]] <line:34:1, col:31> col:5 also_before_non_template 'int (T)'
+// CHECK-NEXT: |   |-ParmVarDecl [[ADDR_90:0x[a-z0-9]*]] <col:30> col:31 'T'
+// CHECK-NEXT: |   `-OMPDeclareVariantAttr [[ADDR_91:0x[a-z0-9]*]] <<invalid sloc>> Implicit implementation={extension(allow_templates)}
+// CHECK-NEXT: |     `-DeclRefExpr [[ADDR_92:0x[a-z0-9]*]] <col:1> 'int (T)' Function [[ADDR_93:0x[a-z0-9]*]] 'also_before_non_template[implementation={extension(allow_templates)}]' 'int (T)'
+// CHECK-NEXT: |-FunctionTemplateDecl [[ADDR_94:0x[a-z0-9]*]] <line:33:1, line:36:1> line:34:1 also_before_non_template[implementation={extension(allow_templates)}]
+// CHECK-NEXT: | |-TemplateTypeParmDecl [[ADDR_88]] <line:33:10, col:19> col:19 referenced typename depth 0 index 0 T
+// CHECK-NEXT: | `-FunctionDecl [[ADDR_93]] <line:34:1, line:36:1> line:34:1 also_before_non_template[implementation={extension(allow_templates)}] 'int (T)'
+// CHECK-NEXT: |   |-ParmVarDecl [[ADDR_90]] <col:30> col:31 'T'
+// CHECK-NEXT: |   `-CompoundStmt [[ADDR_95:0x[a-z0-9]*]] <col:33, line:36:1>
+// CHECK-NEXT: |     `-ReturnStmt [[ADDR_96:0x[a-z0-9]*]] <line:35:3, col:10>
+// CHECK-NEXT: |       `-IntegerLiteral [[ADDR_97:0x[a-z0-9]*]] <col:10> 'int' 4
+// CHECK-NEXT: |-FunctionTemplateDecl [[ADDR_98:0x[a-z0-9]*]] <line:37:1, line:38:18> col:5 implicit only_def
+// CHECK-NEXT: | |-NonTypeTemplateParmDecl [[ADDR_99:0x[a-z0-9]*]] <line:37:10, col:14> col:14 'int' depth 0 index 0 V
+// CHECK-NEXT: | |-FunctionDecl [[ADDR_100:0x[a-z0-9]*]] <line:38:1, col:18> col:5 only_def 'int ({{.*}})'
+// CHECK-NEXT: | | `-OMPDeclareVariantAttr [[ADDR_101:0x[a-z0-9]*]] <<invalid sloc>> Implicit implementation={extension(allow_templates)}
+// CHECK-NEXT: | |   `-DeclRefExpr [[ADDR_102:0x[a-z0-9]*]] <col:1> 'int ({{.*}})' Function [[ADDR_103:0x[a-z0-9]*]] 'only_def[implementation={extension(allow_templates)}]' 'int ({{.*}})'
+// CHECK-NEXT: | `-FunctionDecl [[ADDR_104:0x[a-z0-9]*]] <col:1, col:18> col:5 used only_def 'int ({{.*}})'
+// CHECK-NEXT: |   |-TemplateArgument integral 0
+// CHECK-NEXT: |   `-OMPDeclareVariantAttr [[ADDR_105:0x[a-z0-9]*]] <<invalid sloc>> Implicit implementation={extension(allow_templates)}
+// CHECK-NEXT: |     `-DeclRefExpr [[ADDR_106:0x[a-z0-9]*]] <col:1> 'int ({{.*}})' Function [[ADDR_107:0x[a-z0-9]*]] 'only_def[implementation={extension(allow_templates)}]' 'int ({{.*}})'
+// CHECK-NEXT: |-FunctionTemplateDecl [[ADDR_108:0x[a-z0-9]*]] <line:37:1, line:40:1> line:38:1 only_def[implementation={extension(allow_templates)}]
+// CHECK-NEXT: | |-NonTypeTemplateParmDecl [[ADDR_99]] <line:37:10, col:14> col:14 'int' depth 0 index 0 V
+// CHECK-NEXT: | |-FunctionDecl [[ADDR_103]] <line:38:1, line:40:1> line:38:1 referenced only_def[implementation={extension(allow_templates)}] 'int ({{.*}})'
+// CHECK-NEXT: | | `-CompoundStmt [[ADDR_109:0x[a-z0-9]*]] <col:20, line:40:1>
+// CHECK-NEXT: | |   `-ReturnStmt [[ADDR_110:0x[a-z0-9]*]] <line:39:3, col:10>
+// CHECK-NEXT: | |     `-IntegerLiteral [[ADDR_111:0x[a-z0-9]*]] <col:10> 'int' 0
+// CHECK-NEXT: | `-FunctionDecl [[ADDR_107]] <line:38:1, line:40:1> line:38:1 only_def[implementation={extension(allow_templates)}] 'int ({{.*}})'
+// CHECK-NEXT: |   |-TemplateArgument integral 0
+// CHECK-NEXT: |   `-CompoundStmt [[ADDR_112:0x[a-z0-9]*]] <col:20, line:40:1>
+// CHECK-NEXT: |     `-ReturnStmt [[ADDR_113:0x[a-z0-9]*]] <line:39:3, col:10>
+// CHECK-NEXT: |       `-IntegerLiteral [[ADDR_111]] <col:10> 'int' 0
+// CHECK-NEXT: |-FunctionTemplateDecl [[ADDR_114:0x[a-z0-9]*]] prev [[ADDR_40]] <line:43:1, line:46:1> line:44:5 also_after
+// CHECK-NEXT: | |-TemplateTypeParmDecl [[ADDR_115:0x[a-z0-9]*]] <line:43:10, col:19> col:19 referenced typename depth 0 index 0 T
+// CHECK-NEXT: | |-FunctionDecl [[ADDR_116:0x[a-z0-9]*]] prev [[ADDR_42]] <line:44:1, line:46:1> line:44:5 also_after 'int (T)'
+// CHECK-NEXT: | | |-ParmVarDecl [[ADDR_117:0x[a-z0-9]*]] <col:16> col:17 'T'
+// CHECK-NEXT: | | |-CompoundStmt [[ADDR_118:0x[a-z0-9]*]] <col:19, line:46:1>
+// CHECK-NEXT: | | | `-ReturnStmt [[ADDR_119:0x[a-z0-9]*]] <line:45:3, col:10>
+// CHECK-NEXT: | | |   `-IntegerLiteral [[ADDR_52]] <col:10> 'int' 6
+// CHECK-NEXT: | | `-OMPDeclareVariantAttr [[ADDR_120:0x[a-z0-9]*]] <<invalid sloc>> Inherited Implicit implementation={extension(allow_templates)}
+// CHECK-NEXT: | |   `-DeclRefExpr [[ADDR_45]] <line:22:1> 'int (T)' Function [[ADDR_46]] 'also_after[implementation={extension(allow_templates)}]' 'int (T)'
+// CHECK-NEXT: | `-Function [[ADDR_47]] 'also_after' 'int (char)'
+// CHECK-NEXT: |-FunctionTemplateDecl [[ADDR_121:0x[a-z0-9]*]] <line:47:1, line:50:1> line:48:5 also_after_mismatch
+// CHECK-NEXT: | |-TemplateTypeParmDecl [[ADDR_122:0x[a-z0-9]*]] <line:47:10, col:19> col:19 referenced typename depth 0 index 0 T
+// CHECK-NEXT: | |-FunctionDecl [[ADDR_123:0x[a-z0-9]*]] <line:48:1, line:50:1> line:48:5 also_after_mismatch 'int (T)'
+// CHECK-NEXT: | | |-ParmVarDecl [[ADDR_124:0x[a-z0-9]*]] <col:25> col:26 'T'
+// CHECK-NEXT: | | `-CompoundStmt [[ADDR_125:0x[a-z0-9]*]] <col:28, line:50:1>
+// CHECK-NEXT: | |   `-ReturnStmt [[ADDR_126:0x[a-z0-9]*]] <line:49:3, col:10>
+// CHECK-NEXT: | |     `-IntegerLiteral [[ADDR_127:0x[a-z0-9]*]] <col:10> 'int' 0
+// CHECK-NEXT: | `-FunctionDecl [[ADDR_128:0x[a-z0-9]*]] <line:48:1, line:50:1> line:48:5 used also_after_mismatch 'int (int)'
+// CHECK-NEXT: |   |-TemplateArgument type 'int'
+// CHECK-NEXT: |   | `-BuiltinType [[ADDR_129:0x[a-z0-9]*]] 'int'
+// CHECK-NEXT: |   |-ParmVarDecl [[ADDR_130:0x[a-z0-9]*]] <col:25> col:26 'int':'int'
+// CHECK-NEXT: |   `-CompoundStmt [[ADDR_131:0x[a-z0-9]*]] <col:28, line:50:1>
+// CHECK-NEXT: |     `-ReturnStmt [[ADDR_132:0x[a-z0-9]*]] <line:49:3, col:10>
+// CHECK-NEXT: |       `-IntegerLiteral [[ADDR_127]] <col:10> 'int' 0
+// CHECK-NEXT: `-FunctionDecl [[ADDR_133:0x[a-z0-9]*]] <line:52:1, line:55:1> line:52:5 test 'int ({{.*}})'
+// CHECK-NEXT:   `-CompoundStmt [[ADDR_134:0x[a-z0-9]*]] <col:12, line:55:1>
+// CHECK-NEXT:     `-ReturnStmt [[ADDR_135:0x[a-z0-9]*]] <line:54:3, col:144>
+// CHECK-NEXT:       `-BinaryOperator [[ADDR_136:0x[a-z0-9]*]] <col:10, col:144> 'int' '+'
+// CHECK-NEXT:         |-BinaryOperator [[ADDR_137:0x[a-z0-9]*]] <col:10, col:128> 'int' '+'
+// CHECK-NEXT:         | |-BinaryOperator [[ADDR_138:0x[a-z0-9]*]] <col:10, col:103> 'int' '+'
+// CHECK-NEXT:         | | |-BinaryOperator [[ADDR_139:0x[a-z0-9]*]] <col:10, col:81> 'int' '+'
+// CHECK-NEXT:         | | | |-BinaryOperator [[ADDR_140:0x[a-z0-9]*]] <col:10, col:52> 'int' '+'
+// CHECK-NEXT:         | | | | |-PseudoObjectExpr [[ADDR_141:0x[a-z0-9]*]] <col:10, col:24> 'int'
+// CHECK-NEXT:         | | | | | |-CallExpr [[ADDR_142:0x[a-z0-9]*]] <col:10, col:24> 'int'
+// CHECK-NEXT:         | | | | | | |-ImplicitCastExpr [[ADDR_143:0x[a-z0-9]*]] <col:10> 'int (*)(double)' <FunctionToPointerDecay>
+// CHECK-NEXT:         | | | | | | | `-DeclRefExpr [[ADDR_144:0x[a-z0-9]*]] <col:10> 'int (double)' {{.*}}Function [[ADDR_10]] 'also_before' 'int (double)' (FunctionTemplate [[ADDR_0]] 'also_before')
+// CHECK-NEXT:         | | | | | | `-FloatingLiteral [[ADDR_145:0x[a-z0-9]*]] <col:22> 'double' 0.000000e+00
+// CHECK-NEXT:         | | | | | `-CallExpr [[ADDR_146:0x[a-z0-9]*]] <line:18:1, line:54:24> 'int'
+// CHECK-NEXT:         | | | | |   |-ImplicitCastExpr [[ADDR_147:0x[a-z0-9]*]] <line:18:1> 'int (*)(double)' <FunctionToPointerDecay>
+// CHECK-NEXT:         | | | | |   | `-DeclRefExpr [[ADDR_16]] <col:1> 'int (double)' Function [[ADDR_17]] 'also_before[implementation={extension(allow_templates)}]' 'int (double)'
+// CHECK-NEXT:         | | | | |   `-FloatingLiteral [[ADDR_145]] <line:54:22> 'double' 0.000000e+00
+// CHECK-NEXT:         | | | | `-CallExpr [[ADDR_148:0x[a-z0-9]*]] <col:28, col:52> 'int'
+// CHECK-NEXT:         | | | |   `-ImplicitCastExpr [[ADDR_149:0x[a-z0-9]*]] <col:28, col:50> 'int (*)({{.*}})' <FunctionToPointerDecay>
+// CHECK-NEXT:         | | | |     `-DeclRefExpr [[ADDR_150:0x[a-z0-9]*]] <col:28, col:50> 'int ({{.*}})' {{.*}}Function [[ADDR_24]] 'also_before_mismatch' 'int ({{.*}})' (FunctionTemplate [[ADDR_18]] 'also_before_mismatch')
+// CHECK-NEXT:         | | | `-CallExpr [[ADDR_151:0x[a-z0-9]*]] <col:56, col:81> 'int'
+// CHECK-NEXT:         | | |   `-ImplicitCastExpr [[ADDR_152:0x[a-z0-9]*]] <col:56> 'int (*)({{.*}})' <FunctionToPointerDecay>
+// CHECK-NEXT:         | | |     `-DeclRefExpr [[ADDR_153:0x[a-z0-9]*]] <col:56> 'int ({{.*}})' {{.*}}Function [[ADDR_27]] 'also_before_non_template' 'int ({{.*}})'
+// CHECK-NEXT:         | | `-PseudoObjectExpr [[ADDR_154:0x[a-z0-9]*]] <col:85, col:103> 'int'
+// CHECK-NEXT:         | |   |-CallExpr [[ADDR_155:0x[a-z0-9]*]] <col:85, col:103> 'int'
+// CHECK-NEXT:         | |   | |-ImplicitCastExpr [[ADDR_156:0x[a-z0-9]*]] <col:85, col:100> 'int (*)(char)' <FunctionToPointerDecay>
+// CHECK-NEXT:         | |   | | `-DeclRefExpr [[ADDR_157:0x[a-z0-9]*]] <col:85, col:100> 'int (char)' {{.*}}Function [[ADDR_47]] 'also_after' 'int (char)' (FunctionTemplate [[ADDR_114]] 'also_after')
+// CHECK-NEXT:         | |   | `-ImplicitCastExpr [[ADDR_158:0x[a-z0-9]*]] <col:102> 'char':'char' <IntegralCast>
+// CHECK-NEXT:         | |   |   `-IntegerLiteral [[ADDR_159:0x[a-z0-9]*]] <col:102> 'int' 0
+// CHECK-NEXT:         | |   `-CallExpr [[ADDR_160:0x[a-z0-9]*]] <line:22:1, line:54:103> 'int'
+// CHECK-NEXT:         | |     |-ImplicitCastExpr [[ADDR_161:0x[a-z0-9]*]] <line:22:1> 'int (*)(char)' <FunctionToPointerDecay>
+// CHECK-NEXT:         | |     | `-DeclRefExpr [[ADDR_54]] <col:1> 'int (char)' Function [[ADDR_55]] 'also_after[implementation={extension(allow_templates)}]' 'int (char)'
+// CHECK-NEXT:         | |     `-ImplicitCastExpr [[ADDR_162:0x[a-z0-9]*]] <line:54:102> 'char':'char' <IntegralCast>
+// CHECK-NEXT:         | |       `-IntegerLiteral [[ADDR_159]] <col:102> 'int' 0
+// CHECK-NEXT:         | `-CallExpr [[ADDR_163:0x[a-z0-9]*]] <col:107, col:128> 'int'
+// CHECK-NEXT:         |   |-ImplicitCastExpr [[ADDR_164:0x[a-z0-9]*]] <col:107> 'int (*)(int)' <FunctionToPointerDecay>
+// CHECK-NEXT:         |   | `-DeclRefExpr [[ADDR_165:0x[a-z0-9]*]] <col:107> 'int (int)' {{.*}}Function [[ADDR_128]] 'also_after_mismatch' 'int (int)' (FunctionTemplate [[ADDR_121]] 'also_after_mismatch')
+// CHECK-NEXT:         |   `-IntegerLiteral [[ADDR_166:0x[a-z0-9]*]] <col:127> 'int' 0
+// CHECK-NEXT:         `-PseudoObjectExpr [[ADDR_167:0x[a-z0-9]*]] <col:132, col:144> 'int'
+// CHECK-NEXT:           |-CallExpr [[ADDR_168:0x[a-z0-9]*]] <col:132, col:144> 'int'
+// CHECK-NEXT:           | `-ImplicitCastExpr [[ADDR_169:0x[a-z0-9]*]] <col:132, col:142> 'int (*)({{.*}})' <FunctionToPointerDecay>
+// CHECK-NEXT:           |   `-DeclRefExpr [[ADDR_170:0x[a-z0-9]*]] <col:132, col:142> 'int ({{.*}})' {{.*}}Function [[ADDR_104]] 'only_def' 'int ({{.*}})' (FunctionTemplate [[ADDR_98]] 'only_def')
+// CHECK-NEXT:           `-CallExpr [[ADDR_171:0x[a-z0-9]*]] <line:38:1, line:54:144> 'int'
+// CHECK-NEXT:             `-ImplicitCastExpr [[ADDR_172:0x[a-z0-9]*]] <line:38:1> 'int (*)({{.*}})' <FunctionToPointerDecay>
+// CHECK-NEXT:               `-DeclRefExpr [[ADDR_106]] <col:1> 'int ({{.*}})' Function [[ADDR_107]] 'only_def[implementation={extension(allow_templates)}]' 'int ({{.*}})'

llvm/include/llvm/Frontend/OpenMP/OMPKinds.def

 __OMP_TRAIT_PROPERTY(implementation, vendor, ti)
 __OMP_TRAIT_PROPERTY(implementation, vendor, unknown)
 
 __OMP_TRAIT_SELECTOR(implementation, extension, true)
 __OMP_TRAIT_PROPERTY(implementation, extension, match_all)
 __OMP_TRAIT_PROPERTY(implementation, extension, match_any)
 __OMP_TRAIT_PROPERTY(implementation, extension, match_none)
 __OMP_TRAIT_PROPERTY(implementation, extension, disable_implicit_base)
+__OMP_TRAIT_PROPERTY(implementation, extension, allow_templates)
 
 __OMP_TRAIT_SET(user)
 
 __OMP_TRAIT_SELECTOR(user, condition, true)
 
 __OMP_TRAIT_PROPERTY(user, condition, true)
 __OMP_TRAIT_PROPERTY(user, condition, false)
 __OMP_TRAIT_PROPERTY(user, condition, unknown)