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[clang] remove workaround for SubstNonTypeTemplateParmExpr transform #158541

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[clang] remove workaround for SubstNonTypeTemplateParmExpr transform #158541

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42 changes: 7 additions & 35 deletions clang/lib/Sema/SemaTemplateInstantiate.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2441,45 +2441,17 @@ TemplateInstantiator::TransformSubstNonTypeTemplateParmPackExpr(
ExprResult
TemplateInstantiator::TransformSubstNonTypeTemplateParmExpr(
SubstNonTypeTemplateParmExpr *E) {
ExprResult SubstReplacement = E->getReplacement();
if (!isa<ConstantExpr>(SubstReplacement.get()))
SubstReplacement = TransformExpr(E->getReplacement());
ExprResult SubstReplacement = TransformExpr(E->getReplacement());
if (SubstReplacement.isInvalid())
return true;
QualType SubstType = TransformType(E->getParameterType(getSema().Context));
if (SubstType.isNull())
return true;
// The type may have been previously dependent and not now, which means we
// might have to implicit cast the argument to the new type, for example:
// template<auto T, decltype(T) U>
// concept C = sizeof(U) == 4;
// void foo() requires C<2, 'a'> { }
// When normalizing foo(), we first form the normalized constraints of C:
// AtomicExpr(sizeof(U) == 4,
// U=SubstNonTypeTemplateParmExpr(Param=U,
// Expr=DeclRef(U),
// Type=decltype(T)))
// Then we substitute T = 2, U = 'a' into the parameter mapping, and need to
// produce:
// AtomicExpr(sizeof(U) == 4,
// U=SubstNonTypeTemplateParmExpr(Param=U,
// Expr=ImpCast(
// decltype(2),
// SubstNTTPE(Param=U, Expr='a',
// Type=char)),
// Type=decltype(2)))
// The call to CheckTemplateArgument here produces the ImpCast.
TemplateArgument SugaredConverted, CanonicalConverted;
if (SemaRef
.CheckTemplateArgument(E->getParameter(), SubstType,
SubstReplacement.get(), SugaredConverted,
CanonicalConverted,
/*StrictCheck=*/false, Sema::CTAK_Specified)
.isInvalid())
auto *Param = cast_or_null<NonTypeTemplateParmDecl>(
TransformDecl(E->getNameLoc(), E->getParameter()));
if (!Param)
return true;
return transformNonTypeTemplateParmRef(
E->getAssociatedDecl(), E->getParameter(), E->getExprLoc(),
SugaredConverted, E->getPackIndex(), E->getFinal());
E->getAssociatedDecl(), Param, E->getExprLoc(),
TemplateArgument(SubstReplacement.get(), /*IsCanonical=*/false),
E->getPackIndex(), E->getFinal());
}

ExprResult TemplateInstantiator::RebuildVarDeclRefExpr(ValueDecl *PD,
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2 changes: 1 addition & 1 deletion clang/test/SemaCXX/cxx20-ctad-type-alias.cpp
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Expand Up @@ -113,7 +113,7 @@ using Bar = Foo<X, sizeof(X)>; // expected-note {{candidate template ignored: co
// expected-note {{implicit deduction guide declared as 'template <typename X> requires __is_deducible(test9::Bar, test9::Foo<X, sizeof(X)>) Bar(test9::Foo<X, sizeof(X)>) -> test9::Foo<X, sizeof(X)>'}} \
// expected-note {{implicit deduction guide declared as 'template <typename X> requires __is_deducible(test9::Bar, test9::Foo<X, sizeof(X)>) Bar(const X (&)[sizeof(X)]) -> test9::Foo<X, sizeof(X)>'}} \
// expected-note {{candidate template ignored: constraints not satisfied [with X = int]}} \
// expected-note {{cannot deduce template arguments for 'test9::Bar' from 'test9::Foo<int, 4UL>'}}
// expected-note {{cannot deduce template arguments for 'test9::Bar' from 'test9::Foo<int, sizeof(int)>'}}


Bar s = {{1}}; // expected-error {{no viable constructor or deduction guide }}
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14 changes: 9 additions & 5 deletions clang/test/SemaTemplate/instantiate-template-argument.cpp
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Expand Up @@ -9,20 +9,24 @@ concept C2 = C1<Y{}, V>;
// sizeof(U) >= 4 [U = V (decltype(Y{}))]

template<char W>
constexpr int foo() requires C2<int, W> { return 1; }
constexpr int foo() requires C2<int, W> { return 1; } // #cand1
// sizeof(U) >= 4 [U = W (decltype(int{}))]

template<char X>
// expected-note@+1{{candidate function}}
constexpr int foo() requires C1<1, X> && true { return 2; }
constexpr int foo() requires C1<1, X> && true { return 2; } // #cand2
// sizeof(U) >= 4 [U = X (decltype(1))]

static_assert(foo<'a'>() == 2);
// expected-error@-1 {{call to 'foo' is ambiguous}}
// expected-note@#cand1 {{candidate function}}
// expected-note@#cand2 {{candidate function}}

template<char Z>
// expected-note@+1{{candidate function}}
constexpr int foo() requires C2<long long, Z> && true { return 3; }
constexpr int foo() requires C2<long long, Z> && true { return 3; } // #cand3
// sizeof(U) >= 4 [U = Z (decltype(long long{}))]

static_assert(foo<'a'>() == 3);
// expected-error@-1{{call to 'foo' is ambiguous}}
// expected-error@-1{{call to 'foo' is ambiguous}}
// expected-note@#cand1 {{candidate function}}
// expected-note@#cand3 {{candidate function}}