[clang] [clang] fix matching of nested template template parameters (PR #130447)
Matheus Izvekov via cfe-commits
cfe-commits at lists.llvm.org
Sun Mar 9 09:35:56 PDT 2025
https://github.com/mizvekov updated https://github.com/llvm/llvm-project/pull/130447
>From 78ac2f4cbc45c4f77aab5e28e3450e9c459b8077 Mon Sep 17 00:00:00 2001
From: Matheus Izvekov <mizvekov at gmail.com>
Date: Sat, 8 Mar 2025 20:32:14 -0300
Subject: [PATCH] [clang] fix matching of nested template template parameters
When checking the template template parameters of template template
parameters, the PartialOrdering context was not correctly propagated.
This also has a few drive-by fixes, such as checking the template parameter
lists of template template parameters, which was previously missing and
would have been it's own bug, but we need to fix it in order to
prevent crashes in error recovery in a simple way.
Fixes #130362
---
clang/docs/ReleaseNotes.rst | 7 ++--
clang/include/clang/Sema/Sema.h | 8 +++--
clang/lib/Sema/SemaDecl.cpp | 2 +-
clang/lib/Sema/SemaDeclCXX.cpp | 2 +-
clang/lib/Sema/SemaTemplate.cpp | 36 ++++++++++++-------
clang/lib/Sema/SemaTemplateDeduction.cpp | 16 +++++----
.../lib/Sema/SemaTemplateInstantiateDecl.cpp | 2 +-
clang/test/SemaTemplate/cwg2398.cpp | 17 ++++-----
.../SemaTemplate/temp_arg_template_p0522.cpp | 3 +-
clang/unittests/AST/DeclPrinterTest.cpp | 16 ++++-----
10 files changed, 63 insertions(+), 46 deletions(-)
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 7859871b0493a..d6627d21e5e3d 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -161,8 +161,8 @@ related warnings within the method body.
``__attribute__((model("large")))`` on non-TLS globals in x86-64 compilations.
This forces the global to be considered small or large in regards to the
x86-64 code model, regardless of the code model specified for the compilation.
-- Clang now emits a warning ``-Wreserved-init-priority`` instead of a hard error
- when ``__attribute__((init_priority(n)))`` is used with values of n in the
+- Clang now emits a warning ``-Wreserved-init-priority`` instead of a hard error
+ when ``__attribute__((init_priority(n)))`` is used with values of n in the
reserved range [0, 100]. The warning will be treated as an error by default.
- There is a new ``format_matches`` attribute to complement the existing
@@ -294,6 +294,9 @@ Bug Fixes to C++ Support
direct-list-initialized from an array is corrected to direct-initialization.
- Clang no longer crashes when a coroutine is declared ``[[noreturn]]``. (#GH127327)
- Clang now uses the parameter location for abbreviated function templates in ``extern "C"``. (#GH46386)
+- Fixes matching of nested template template parameters. (#GH130362)
+- Correctly diagnoses template template paramters which have a pack parameter
+ not in the last position.
Improvements to C++ diagnostics
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index fdef57e84ee3d..eff533cf74682 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -11363,14 +11363,16 @@ class Sema final : public SemaBase {
/// The context in which we are checking a template parameter list.
enum TemplateParamListContext {
- TPC_ClassTemplate,
- TPC_VarTemplate,
+ // For this context, Class, Variable, TypeAlias, and non-pack Template
+ // Template Parameters are the same.
+ TPC_Other,
+
TPC_FunctionTemplate,
TPC_ClassTemplateMember,
TPC_FriendClassTemplate,
TPC_FriendFunctionTemplate,
TPC_FriendFunctionTemplateDefinition,
- TPC_TypeAliasTemplate
+ TPC_TemplateTemplateParameterPack,
};
/// Checks the validity of a template parameter list, possibly
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 5716eb61d4ae8..02817775215f7 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -8165,7 +8165,7 @@ NamedDecl *Sema::ActOnVariableDeclarator(
(D.getCXXScopeSpec().isSet() && DC && DC->isRecord() &&
DC->isDependentContext())
? TPC_ClassTemplateMember
- : TPC_VarTemplate))
+ : TPC_Other))
NewVD->setInvalidDecl();
// If we are providing an explicit specialization of a static variable
diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index fd5f0443fa894..1edbe62f1c79a 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -13586,7 +13586,7 @@ Decl *Sema::ActOnAliasDeclaration(Scope *S, AccessSpecifier AS,
// Merge any previous default template arguments into our parameters,
// and check the parameter list.
if (CheckTemplateParameterList(TemplateParams, OldTemplateParams,
- TPC_TypeAliasTemplate))
+ TPC_Other))
return nullptr;
TypeAliasTemplateDecl *NewDecl =
diff --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
index 0caabc6573361..465191c1e1828 100644
--- a/clang/lib/Sema/SemaTemplate.cpp
+++ b/clang/lib/Sema/SemaTemplate.cpp
@@ -1593,8 +1593,16 @@ NamedDecl *Sema::ActOnTemplateTemplateParameter(
assert(S->isTemplateParamScope() &&
"Template template parameter not in template parameter scope!");
- // Construct the parameter object.
bool IsParameterPack = EllipsisLoc.isValid();
+
+ bool Invalid = false;
+ if (CheckTemplateParameterList(
+ Params,
+ /*OldParams=*/nullptr,
+ IsParameterPack ? TPC_TemplateTemplateParameterPack : TPC_Other))
+ Invalid = true;
+
+ // Construct the parameter object.
TemplateTemplateParmDecl *Param = TemplateTemplateParmDecl::Create(
Context, Context.getTranslationUnitDecl(),
NameLoc.isInvalid() ? TmpLoc : NameLoc, Depth, Position, IsParameterPack,
@@ -1617,9 +1625,12 @@ NamedDecl *Sema::ActOnTemplateTemplateParameter(
if (Params->size() == 0) {
Diag(Param->getLocation(), diag::err_template_template_parm_no_parms)
<< SourceRange(Params->getLAngleLoc(), Params->getRAngleLoc());
- Param->setInvalidDecl();
+ Invalid = true;
}
+ if (Invalid)
+ Param->setInvalidDecl();
+
// C++0x [temp.param]p9:
// A default template-argument may be specified for any kind of
// template-parameter that is not a template parameter pack.
@@ -2068,7 +2079,7 @@ DeclResult Sema::CheckClassTemplate(
SemanticContext->isDependentContext())
? TPC_ClassTemplateMember
: TUK == TagUseKind::Friend ? TPC_FriendClassTemplate
- : TPC_ClassTemplate,
+ : TPC_Other,
SkipBody))
Invalid = true;
@@ -2210,9 +2221,8 @@ static bool DiagnoseDefaultTemplateArgument(Sema &S,
SourceLocation ParamLoc,
SourceRange DefArgRange) {
switch (TPC) {
- case Sema::TPC_ClassTemplate:
- case Sema::TPC_VarTemplate:
- case Sema::TPC_TypeAliasTemplate:
+ case Sema::TPC_Other:
+ case Sema::TPC_TemplateTemplateParameterPack:
return false;
case Sema::TPC_FunctionTemplate:
@@ -2385,8 +2395,11 @@ bool Sema::CheckTemplateParameterList(TemplateParameterList *NewParams,
MissingDefaultArg = true;
} else if (NonTypeTemplateParmDecl *NewNonTypeParm
= dyn_cast<NonTypeTemplateParmDecl>(*NewParam)) {
- // Check for unexpanded parameter packs.
- if (!NewNonTypeParm->isParameterPack() &&
+ // Check for unexpanded parameter packs, except in a template template
+ // parameter pack, as in those any unexpanded packs should be expanded
+ // along with the parameter itself.
+ if (TPC != TPC_TemplateTemplateParameterPack &&
+ !NewNonTypeParm->isParameterPack() &&
DiagnoseUnexpandedParameterPack(NewNonTypeParm->getLocation(),
NewNonTypeParm->getTypeSourceInfo(),
UPPC_NonTypeTemplateParameterType)) {
@@ -2494,8 +2507,7 @@ bool Sema::CheckTemplateParameterList(TemplateParameterList *NewParams,
// If a template parameter of a primary class template or alias template
// is a template parameter pack, it shall be the last template parameter.
if (SawParameterPack && (NewParam + 1) != NewParamEnd &&
- (TPC == TPC_ClassTemplate || TPC == TPC_VarTemplate ||
- TPC == TPC_TypeAliasTemplate)) {
+ (TPC == TPC_Other || TPC == TPC_TemplateTemplateParameterPack)) {
Diag((*NewParam)->getLocation(),
diag::err_template_param_pack_must_be_last_template_parameter);
Invalid = true;
@@ -2528,8 +2540,8 @@ bool Sema::CheckTemplateParameterList(TemplateParameterList *NewParams,
<< PrevModuleName;
Invalid = true;
} else if (MissingDefaultArg &&
- (TPC == TPC_ClassTemplate || TPC == TPC_FriendClassTemplate ||
- TPC == TPC_VarTemplate || TPC == TPC_TypeAliasTemplate)) {
+ (TPC == TPC_Other || TPC == TPC_TemplateTemplateParameterPack ||
+ TPC == TPC_FriendClassTemplate)) {
// C++ 23[temp.param]p14:
// If a template-parameter of a class template, variable template, or
// alias template has a default template argument, each subsequent
diff --git a/clang/lib/Sema/SemaTemplateDeduction.cpp b/clang/lib/Sema/SemaTemplateDeduction.cpp
index b1a1f86c5cfe1..a6090e4ded6a2 100644
--- a/clang/lib/Sema/SemaTemplateDeduction.cpp
+++ b/clang/lib/Sema/SemaTemplateDeduction.cpp
@@ -3427,9 +3427,9 @@ static TemplateDeductionResult FinishTemplateArgumentDeduction(
if (!P.isPackExpansion() && !A.isPackExpansion()) {
Info.Param =
makeTemplateParameter(Template->getTemplateParameters()->getParam(
- (PsStack.empty() ? TemplateArgs.end()
- : PsStack.front().begin()) -
- TemplateArgs.begin()));
+ (AsStack.empty() ? CTAI.CanonicalConverted.end()
+ : AsStack.front().begin()) -
+ 1 - CTAI.CanonicalConverted.begin()));
Info.FirstArg = P;
Info.SecondArg = A;
return TemplateDeductionResult::NonDeducedMismatch;
@@ -6642,17 +6642,19 @@ bool Sema::isTemplateTemplateParameterAtLeastAsSpecializedAs(
TemplateDeductionResult TDK;
runWithSufficientStackSpace(Info.getLocation(), [&] {
- TDK = ::FinishTemplateArgumentDeduction(
- *this, AArg, /*IsPartialOrdering=*/true, PArgs, Deduced, Info);
+ TDK = ::FinishTemplateArgumentDeduction(*this, AArg, PartialOrdering, PArgs,
+ Deduced, Info);
});
switch (TDK) {
case TemplateDeductionResult::Success:
return true;
// It doesn't seem possible to get a non-deduced mismatch when partial
- // ordering TTPs.
+ // ordering TTPs, except with an invalid template parameter list which has
+ // a parameter after a pack.
case TemplateDeductionResult::NonDeducedMismatch:
- llvm_unreachable("Unexpected NonDeducedMismatch");
+ assert(PArg->isInvalidDecl() && "Unexpected NonDeducedMismatch");
+ return false;
// Substitution failures should have already been diagnosed.
case TemplateDeductionResult::AlreadyDiagnosed:
diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
index cb434dcf6eb9a..a231ad72a9e7c 100644
--- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -2176,7 +2176,7 @@ Decl *TemplateDeclInstantiator::VisitClassTemplateDecl(ClassTemplateDecl *D) {
// Do some additional validation, then merge default arguments
// from the existing declarations.
if (SemaRef.CheckTemplateParameterList(InstParams, PrevParams,
- Sema::TPC_ClassTemplate))
+ Sema::TPC_Other))
return nullptr;
Inst->setAccess(PrevClassTemplate->getAccess());
diff --git a/clang/test/SemaTemplate/cwg2398.cpp b/clang/test/SemaTemplate/cwg2398.cpp
index 3fb5eb6d1c3ac..bde8e58fcd802 100644
--- a/clang/test/SemaTemplate/cwg2398.cpp
+++ b/clang/test/SemaTemplate/cwg2398.cpp
@@ -602,6 +602,11 @@ namespace regression3 {
template <class...> class B {};
template struct A<B, Node<None>>;
} // namespace regression3
+namespace regression4 {
+ template <template <template <class... T1> class TT1> class TT2> struct A {};
+ template <template <class U1> class UU1> struct B {};
+ template struct A<B>;
+} // namespace regression4
namespace nttp_auto {
namespace t1 {
@@ -610,24 +615,16 @@ namespace nttp_auto {
template struct A<B>;
} // namespace t1
namespace t2 {
- // FIXME: Shouldn't accept parameters after a parameter pack.
template<template<auto... Va1, auto Va2> class> struct A {};
- // expected-error at -1 {{deduced non-type template argument does not have the same type as the corresponding template parameter ('auto' vs 'int')}}
- // expected-note at -2 {{template parameter is declared here}}
+ // expected-error at -1 {{template parameter pack must be the last template parameter}}
template<int... Vi> struct B;
- // expected-note at -1 {{template parameter is declared here}}
template struct A<B>;
- // expected-note at -1 {{template template argument is incompatible}}
} // namespace t2
namespace t3 {
- // FIXME: Shouldn't accept parameters after a parameter pack.
template<template<auto... Va1, auto... Va2> class> struct A {};
- // expected-error at -1 {{deduced non-type template argument does not have the same type as the corresponding template parameter ('auto' vs 'int')}}
- // expected-note at -2 {{template parameter is declared here}}
+ // expected-error at -1 {{template parameter pack must be the last template parameter}}
template<int... Vi> struct B;
- // expected-note at -1 {{template parameter is declared here}}
template struct A<B>;
- // expected-note at -1 {{template template argument is incompatible}}
} // namespace t3
} // namespace nttp_auto
diff --git a/clang/test/SemaTemplate/temp_arg_template_p0522.cpp b/clang/test/SemaTemplate/temp_arg_template_p0522.cpp
index e9084d1c27413..993930a28809d 100644
--- a/clang/test/SemaTemplate/temp_arg_template_p0522.cpp
+++ b/clang/test/SemaTemplate/temp_arg_template_p0522.cpp
@@ -5,7 +5,8 @@
template<template<int> typename> struct Ti; // #Ti
template<template<int...> typename> struct TPi; // #TPi
template<template<int, int...> typename> struct TiPi;
-template<template<int..., int...> typename> struct TPiPi; // FIXME: Why is this not ill-formed?
+template<template<int..., int...> typename> struct TPiPi;
+// expected-error at -1 {{template parameter pack must be the last template parameter}}
template<typename T, template<T> typename> struct tT0; // #tT0
template<template<typename T, T> typename> struct Tt0; // #Tt0
diff --git a/clang/unittests/AST/DeclPrinterTest.cpp b/clang/unittests/AST/DeclPrinterTest.cpp
index 6945dff537cae..124b1a166cb18 100644
--- a/clang/unittests/AST/DeclPrinterTest.cpp
+++ b/clang/unittests/AST/DeclPrinterTest.cpp
@@ -1196,21 +1196,21 @@ TEST(DeclPrinter, TestUnnamedTemplateParameters) {
}
TEST(DeclPrinter, TestUnnamedTemplateParametersPacks) {
- ASSERT_TRUE(PrintedDeclCXX17Matches(
- "template <typename ..., int ...,"
- " template <typename ..., bool ...> class ...> void A();",
- functionTemplateDecl(hasName("A")).bind("id"),
- "template <typename ..., int ...,"
- " template <typename ..., bool ...> class ...> void A()"));
+ ASSERT_TRUE(
+ PrintedDeclCXX17Matches("template <typename ..., int ...,"
+ " template <typename ...> class ...> void A();",
+ functionTemplateDecl(hasName("A")).bind("id"),
+ "template <typename ..., int ...,"
+ " template <typename ...> class ...> void A()"));
}
TEST(DeclPrinter, TestNamedTemplateParametersPacks) {
ASSERT_TRUE(PrintedDeclCXX17Matches(
"template <typename ...T, int ...I,"
- " template <typename ...X, bool ...B> class ...Z> void A();",
+ " template <typename ...X> class ...Z> void A();",
functionTemplateDecl(hasName("A")).bind("id"),
"template <typename ...T, int ...I,"
- " template <typename ...X, bool ...B> class ...Z> void A()"));
+ " template <typename ...X> class ...Z> void A()"));
}
TEST(DeclPrinter, TestTemplateTemplateParameterWrittenWithTypename) {
More information about the cfe-commits
mailing list