https://github.com/mizvekov updated
https://github.com/llvm/llvm-project/pull/158541
>From 61ae9330db770dca8f8f9796c741699894154192 Mon Sep 17 00:00:00 2001
From: Matheus Izvekov <mizve...@gmail.com>
Date: Mon, 15 Sep 2025 01:58:01 -0300
Subject: [PATCH] [clang] remove workaround for SubstNonTypeTemplateParmExpr
transform
This removes a workaround which gets in the way of #141776, including
the test changes as expected under that implementation.
---
clang/lib/Sema/SemaTemplateInstantiate.cpp | 38 +++----------------
clang/test/SemaCXX/cxx20-ctad-type-alias.cpp | 2 +-
.../instantiate-template-argument.cpp | 14 ++++---
3 files changed, 16 insertions(+), 38 deletions(-)
diff --git a/clang/lib/Sema/SemaTemplateInstantiate.cpp
b/clang/lib/Sema/SemaTemplateInstantiate.cpp
index a72c95d6d77cf..9db3b07f71f7b 100644
--- a/clang/lib/Sema/SemaTemplateInstantiate.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiate.cpp
@@ -2446,40 +2446,14 @@
TemplateInstantiator::TransformSubstNonTypeTemplateParmExpr(
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,
diff --git a/clang/test/SemaCXX/cxx20-ctad-type-alias.cpp
b/clang/test/SemaCXX/cxx20-ctad-type-alias.cpp
index 1f4d44218ad1f..2f1817d0ca7eb 100644
--- a/clang/test/SemaCXX/cxx20-ctad-type-alias.cpp
+++ b/clang/test/SemaCXX/cxx20-ctad-type-alias.cpp
@@ -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 }}
diff --git a/clang/test/SemaTemplate/instantiate-template-argument.cpp
b/clang/test/SemaTemplate/instantiate-template-argument.cpp
index 43d5d00c8cb20..74050acdf4f35 100644
--- a/clang/test/SemaTemplate/instantiate-template-argument.cpp
+++ b/clang/test/SemaTemplate/instantiate-template-argument.cpp
@@ -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}}
\ No newline at end of file
+// expected-error@-1{{call to 'foo' is ambiguous}}
+// expected-note@#cand1 {{candidate function}}
+// expected-note@#cand3 {{candidate function}}
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