https://github.com/mizvekov created
https://github.com/llvm/llvm-project/pull/130447
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
>From f83e8284a308f6946ee5569d2ebe3c37bae91a86 Mon Sep 17 00:00:00 2001
From: Matheus Izvekov <mizve...@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 | 9 +++--
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, 64 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..9d26df7075c80 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -11363,14 +11363,17 @@ 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_Normal,
+
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..01f44de589fb8 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_Normal))
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..bcd29c95c2ca4 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_Normal))
return nullptr;
TypeAliasTemplateDecl *NewDecl =
diff --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
index 0caabc6573361..2c44bbe1e0f34 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_Normal))
+ 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_Normal,
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_Normal:
+ 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_Normal || 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_Normal || 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..bcfb71f812c7a 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_Normal))
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@-1 {{deduced non-type template argument does not have
the same type as the corresponding template parameter ('auto' vs 'int')}}
- // expected-note@-2 {{template parameter is declared here}}
+ // expected-error@-1 {{template parameter pack must be the last template
parameter}}
template<int... Vi> struct B;
- // expected-note@-1 {{template parameter is declared here}}
template struct A<B>;
- // expected-note@-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@-1 {{deduced non-type template argument does not have
the same type as the corresponding template parameter ('auto' vs 'int')}}
- // expected-note@-2 {{template parameter is declared here}}
+ // expected-error@-1 {{template parameter pack must be the last template
parameter}}
template<int... Vi> struct B;
- // expected-note@-1 {{template parameter is declared here}}
template struct A<B>;
- // expected-note@-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@-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) {
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