[clang] Fix dependence handling of nttp for variable templates (PR #69075)
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Sat Oct 14 11:34:52 PDT 2023
https://github.com/LYP951018 created https://github.com/llvm/llvm-project/pull/69075
The dependence of a template argument is not only determined by the argument itself, but also by the type of the template parameter:
> Furthermore, a non-type [template-argument](https://eel.is/c++draft/temp.names#nt:template-argument) is dependent if the corresponding non-type [template-parameter](https://eel.is/c++draft/temp.param#nt:template-parameter) is of reference or pointer type and the [template-argument](https://eel.is/c++draft/temp.names#nt:template-argument) designates or points to a member of the current instantiation or a member of a dependent type[.](https://eel.is/c++draft/temp.dep#temp-3.sentence-1)
For example:
```cpp
struct A{};
template <const A& T>
const A JoinStringViews = T;
template <int V>
class Builder {
public:
static constexpr A Equal{};
static constexpr auto Val = JoinStringViews<Equal>;
};
```
The constant expression `Equal` is not dependent, but because the type of the template parameter is a reference type and `Equal` is a member of the current instantiation, the template argument of `JoinStringViews<Equal>` is actually dependent, which makes `JoinStringViews<Equal>` dependent.
When a template-id of a variable template is dependent, `CheckVarTemplateId` will return an `UnresolvedLookupExpr`, but `UnresolvedLookupExpr` calculates dependence by template arguments only (the `ConstantExpr` `Equal` here), which is not dependent. This causes type deduction to think that `JoinStringViews<Equal>` is `OverloadTy` and treat it as a function template, which is clearly wrong.
This PR adds a `KnownDependent` parameter to the constructor of `UnresolvedLookupExpr`. After canonicalization, if `CanonicalConverted` contains any dependent argument, `KnownDependent` is set to `true`. This fixes the dependence calculation of `UnresolvedLookupExpr` for dependent variable templates.
Fixes #65153 .
>From 5f3557e274cc2229133fe9d39f787ae8f6eb86c7 Mon Sep 17 00:00:00 2001
From: letrec <liuyupei951018 at hotmail.com>
Date: Sun, 8 Oct 2023 00:44:11 +0800
Subject: [PATCH] Fix dependence handling for variable templates
---
clang/include/clang/AST/ExprCXX.h | 8 ++++++--
clang/lib/AST/ASTImporter.cpp | 5 ++++-
clang/lib/AST/ExprCXX.cpp | 14 +++++++-------
clang/lib/Sema/SemaDeclCXX.cpp | 5 +++--
clang/lib/Sema/SemaTemplate.cpp | 5 +++--
clang/test/SemaTemplate/dependent-expr.cpp | 15 +++++++++++++++
6 files changed, 38 insertions(+), 14 deletions(-)
diff --git a/clang/include/clang/AST/ExprCXX.h b/clang/include/clang/AST/ExprCXX.h
index 17dbb5e888ebdd3..798c98cfcf2d4db 100644
--- a/clang/include/clang/AST/ExprCXX.h
+++ b/clang/include/clang/AST/ExprCXX.h
@@ -3191,7 +3191,8 @@ class UnresolvedLookupExpr final
const DeclarationNameInfo &NameInfo, bool RequiresADL,
bool Overloaded,
const TemplateArgumentListInfo *TemplateArgs,
- UnresolvedSetIterator Begin, UnresolvedSetIterator End);
+ UnresolvedSetIterator Begin, UnresolvedSetIterator End,
+ bool KnownDependent);
UnresolvedLookupExpr(EmptyShell Empty, unsigned NumResults,
bool HasTemplateKWAndArgsInfo);
@@ -3211,12 +3212,15 @@ class UnresolvedLookupExpr final
const DeclarationNameInfo &NameInfo, bool RequiresADL, bool Overloaded,
UnresolvedSetIterator Begin, UnresolvedSetIterator End);
+ // After canonicalization, there may be dependent template arguments in
+ // CanonicalConverted But none of Args is dependent. When any of
+ // CanonicalConverted dependent, KnownDependent is true.
static UnresolvedLookupExpr *
Create(const ASTContext &Context, CXXRecordDecl *NamingClass,
NestedNameSpecifierLoc QualifierLoc, SourceLocation TemplateKWLoc,
const DeclarationNameInfo &NameInfo, bool RequiresADL,
const TemplateArgumentListInfo *Args, UnresolvedSetIterator Begin,
- UnresolvedSetIterator End);
+ UnresolvedSetIterator End, bool KnownDependent);
static UnresolvedLookupExpr *CreateEmpty(const ASTContext &Context,
unsigned NumResults,
diff --git a/clang/lib/AST/ASTImporter.cpp b/clang/lib/AST/ASTImporter.cpp
index c7c2aecc8b179a4..706bbfcadd58b75 100644
--- a/clang/lib/AST/ASTImporter.cpp
+++ b/clang/lib/AST/ASTImporter.cpp
@@ -8391,10 +8391,13 @@ ASTNodeImporter::VisitUnresolvedLookupExpr(UnresolvedLookupExpr *E) {
if (!ToTemplateKeywordLocOrErr)
return ToTemplateKeywordLocOrErr.takeError();
+ const bool KnownDependent =
+ (E->getDependence() & ExprDependence::TypeValue) ==
+ ExprDependence::TypeValue;
return UnresolvedLookupExpr::Create(
Importer.getToContext(), *ToNamingClassOrErr, *ToQualifierLocOrErr,
*ToTemplateKeywordLocOrErr, ToNameInfo, E->requiresADL(), &ToTAInfo,
- ToDecls.begin(), ToDecls.end());
+ ToDecls.begin(), ToDecls.end(), KnownDependent);
}
return UnresolvedLookupExpr::Create(
diff --git a/clang/lib/AST/ExprCXX.cpp b/clang/lib/AST/ExprCXX.cpp
index efb64842fb6d96d..c300ab641257f25 100644
--- a/clang/lib/AST/ExprCXX.cpp
+++ b/clang/lib/AST/ExprCXX.cpp
@@ -354,9 +354,9 @@ UnresolvedLookupExpr::UnresolvedLookupExpr(
NestedNameSpecifierLoc QualifierLoc, SourceLocation TemplateKWLoc,
const DeclarationNameInfo &NameInfo, bool RequiresADL, bool Overloaded,
const TemplateArgumentListInfo *TemplateArgs, UnresolvedSetIterator Begin,
- UnresolvedSetIterator End)
+ UnresolvedSetIterator End, bool KnownDependent)
: OverloadExpr(UnresolvedLookupExprClass, Context, QualifierLoc,
- TemplateKWLoc, NameInfo, TemplateArgs, Begin, End, false,
+ TemplateKWLoc, NameInfo, TemplateArgs, Begin, End, KnownDependent,
false, false),
NamingClass(NamingClass) {
UnresolvedLookupExprBits.RequiresADL = RequiresADL;
@@ -380,7 +380,7 @@ UnresolvedLookupExpr *UnresolvedLookupExpr::Create(
void *Mem = Context.Allocate(Size, alignof(UnresolvedLookupExpr));
return new (Mem) UnresolvedLookupExpr(Context, NamingClass, QualifierLoc,
SourceLocation(), NameInfo, RequiresADL,
- Overloaded, nullptr, Begin, End);
+ Overloaded, nullptr, Begin, End, false);
}
UnresolvedLookupExpr *UnresolvedLookupExpr::Create(
@@ -388,7 +388,7 @@ UnresolvedLookupExpr *UnresolvedLookupExpr::Create(
NestedNameSpecifierLoc QualifierLoc, SourceLocation TemplateKWLoc,
const DeclarationNameInfo &NameInfo, bool RequiresADL,
const TemplateArgumentListInfo *Args, UnresolvedSetIterator Begin,
- UnresolvedSetIterator End) {
+ UnresolvedSetIterator End, bool KnownDependent) {
assert(Args || TemplateKWLoc.isValid());
unsigned NumResults = End - Begin;
unsigned NumTemplateArgs = Args ? Args->size() : 0;
@@ -396,9 +396,9 @@ UnresolvedLookupExpr *UnresolvedLookupExpr::Create(
totalSizeToAlloc<DeclAccessPair, ASTTemplateKWAndArgsInfo,
TemplateArgumentLoc>(NumResults, 1, NumTemplateArgs);
void *Mem = Context.Allocate(Size, alignof(UnresolvedLookupExpr));
- return new (Mem) UnresolvedLookupExpr(Context, NamingClass, QualifierLoc,
- TemplateKWLoc, NameInfo, RequiresADL,
- /*Overloaded*/ true, Args, Begin, End);
+ return new (Mem) UnresolvedLookupExpr(
+ Context, NamingClass, QualifierLoc, TemplateKWLoc, NameInfo, RequiresADL,
+ /*Overloaded*/ true, Args, Begin, End, KnownDependent);
}
UnresolvedLookupExpr *UnresolvedLookupExpr::CreateEmpty(
diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index 2b2b7391f88fd54..4080f1de29bf8de 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -1297,8 +1297,9 @@ static bool checkTupleLikeDecomposition(Sema &S,
// in the associated namespaces.
Expr *Get = UnresolvedLookupExpr::Create(
S.Context, nullptr, NestedNameSpecifierLoc(), SourceLocation(),
- DeclarationNameInfo(GetDN, Loc), /*RequiresADL*/true, &Args,
- UnresolvedSetIterator(), UnresolvedSetIterator());
+ DeclarationNameInfo(GetDN, Loc), /*RequiresADL*/ true, &Args,
+ UnresolvedSetIterator(), UnresolvedSetIterator(),
+ /*KnownDependent*/ false);
Expr *Arg = E.get();
E = S.BuildCallExpr(nullptr, Get, Loc, Arg, Loc);
diff --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
index 994d89e25b3848e..afa654e5c77c251 100644
--- a/clang/lib/Sema/SemaTemplate.cpp
+++ b/clang/lib/Sema/SemaTemplate.cpp
@@ -4981,7 +4981,7 @@ ExprResult Sema::BuildTemplateIdExpr(const CXXScopeSpec &SS,
return ExprError();
}
}
-
+ bool KnownDependent = false;
// In C++1y, check variable template ids.
if (R.getAsSingle<VarTemplateDecl>()) {
ExprResult Res = CheckVarTemplateId(SS, R.getLookupNameInfo(),
@@ -4990,6 +4990,7 @@ ExprResult Sema::BuildTemplateIdExpr(const CXXScopeSpec &SS,
if (Res.isInvalid() || Res.isUsable())
return Res;
// Result is dependent. Carry on to build an UnresolvedLookupEpxr.
+ KnownDependent = true;
}
if (R.getAsSingle<ConceptDecl>()) {
@@ -5007,7 +5008,7 @@ ExprResult Sema::BuildTemplateIdExpr(const CXXScopeSpec &SS,
TemplateKWLoc,
R.getLookupNameInfo(),
RequiresADL, TemplateArgs,
- R.begin(), R.end());
+ R.begin(), R.end(), KnownDependent);
return ULE;
}
diff --git a/clang/test/SemaTemplate/dependent-expr.cpp b/clang/test/SemaTemplate/dependent-expr.cpp
index 51bd375d7920eed..26a7984ccb2c268 100644
--- a/clang/test/SemaTemplate/dependent-expr.cpp
+++ b/clang/test/SemaTemplate/dependent-expr.cpp
@@ -165,3 +165,18 @@ namespace BindingInStmtExpr {
using U = decltype(num_bindings<T>()); // expected-note {{previous}}
using U = N<3>; // expected-error-re {{type alias redefinition with different types ('N<3>' vs {{.*}}N<2>}}
}
+
+namespace PR65153 {
+struct A{};
+
+template <const A& T>
+const A JoinStringViews = T;
+
+template <int V>
+class Builder {
+public:
+ static constexpr A Equal{};
+ // no crash here
+ static constexpr auto Val = JoinStringViews<Equal>;
+};
+} // namespace PR65153
\ No newline at end of file
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