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[clang] fix concepts crash on substitution failure during normalization 

When substitution failed on the first constrained template argument (but
only the first), we would assert / crash. Checking for failure was only
being performed from the second constraint on.

This changes it so the checking is performed in that case,
and the code is also now simplified a little bit to hopefully
avoid this confusion.

Signed-off-by: Matheus Izvekov <mizvekov@gmail.com>

Reviewed By: rsmith

Differential Revision: https://reviews.llvm.org/D106907
This commit is contained in:
Matheus Izvekov 2021-07-26 01:42:14 +02:00
parent 0c7cd4a873
commit 87aa31827b
2 changed files with 20 additions and 12 deletions
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17
clang/lib/Sema/SemaConcept.cpp
View File

@ -742,22 +742,15 @@ Optional<NormalizedConstraint>
NormalizedConstraint::fromConstraintExprs(Sema &S, NamedDecl *D,
ArrayRef<const Expr *> E) {
assert(E.size() != 0);
auto First = fromConstraintExpr(S, D, E[0]);
if (E.size() == 1)
return First;
auto Second = fromConstraintExpr(S, D, E[1]);
if (!Second)
auto Conjunction = fromConstraintExpr(S, D, E[0]);
if (!Conjunction)
return None;
llvm::Optional<NormalizedConstraint> Conjunction;
Conjunction.emplace(S.Context, std::move(*First), std::move(*Second),
CCK_Conjunction);
for (unsigned I = 2; I < E.size(); ++I) {
for (unsigned I = 1; I < E.size(); ++I) {
auto Next = fromConstraintExpr(S, D, E[I]);
if (!Next)
return llvm::Optional<NormalizedConstraint>{};
NormalizedConstraint NewConjunction(S.Context, std::move(*Conjunction),
return None;
*Conjunction = NormalizedConstraint(S.Context, std::move(*Conjunction),
std::move(*Next), CCK_Conjunction);
*Conjunction = std::move(NewConjunction);
}
return Conjunction;
}

15
clang/test/CXX/temp/temp.constr/temp.constr.normal/p1.cpp
View File

@ -67,3 +67,18 @@ namespace non_type_pack {
static_assert((foo<1>(), true));
}
namespace PR47174 {
// This checks that we don't crash with a failed substitution on the first constrained argument when
// performing normalization.
template <Bar2 T, True U>
requires true struct S3; // expected-note {{template is declared here}}
template <True T, True U>
requires true struct S3<T, U>; // expected-error {{class template partial specialization is not more specialized than the primary template}}
// Same as above, for the second position (but this was already working).
template <True T, Bar2 U>
requires true struct S4; // expected-note {{template is declared here}}
template <True T, True U>
requires true struct S4<T, U>; // expected-error {{class template partial specialization is not more specialized than the primary template}}
} // namespace PR47174