This revision was landed with ongoing or failed builds.
This revision was automatically updated to reflect the committed changes.
Closed by commit rGb5d9f00b2096: Forbid implicit conversion of constraint
expression to bool (authored by erichkeane).
Herald added a project: clang.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D141954/new/
https://reviews.llvm.org/D141954
Files:
clang/docs/ReleaseNotes.rst
clang/lib/Sema/SemaConcept.cpp
clang/test/CXX/temp/temp.constr/temp.constr.atomic/constrant-satisfaction-conversions.cpp
Index: clang/test/CXX/temp/temp.constr/temp.constr.atomic/constrant-satisfaction-conversions.cpp
===================================================================
--- /dev/null
+++ clang/test/CXX/temp/temp.constr/temp.constr.atomic/constrant-satisfaction-conversions.cpp
@@ -0,0 +1,67 @@
+// RUN: %clang_cc1 -std=c++20 -x c++ -Wno-constant-logical-operand -verify %s
+
+template<typename T> concept C =
+sizeof(T) == 4 && !true; // requires atomic constraints sizeof(T) == 4 and !true
+
+template<typename T> concept C2 = sizeof(T); // expected-error{{atomic constraint must be of type 'bool' (found }}
+
+template<typename T> struct S {
+ constexpr operator bool() const { return true; }
+};
+
+// expected-error@+3{{atomic constraint must be of type 'bool' (found 'S<int>')}}
+// expected-note@#FINST{{while checking constraint satisfaction}}
+// expected-note@#FINST{{in instantiation of function template specialization}}
+template<typename T> requires (S<T>{})
+void f(T);
+void f(int);
+
+// Ensure this applies to operator && as well.
+// expected-error@+3{{atomic constraint must be of type 'bool' (found 'S<int>')}}
+// expected-note@#F2INST{{while checking constraint satisfaction}}
+// expected-note@#F2INST{{in instantiation of function template specialization}}
+template<typename T> requires (S<T>{} && true)
+void f2(T);
+void f2(int);
+
+template<typename T> requires requires {
+ requires S<T>{};
+ // expected-error@-1{{atomic constraint must be of type 'bool' (found 'S<int>')}}
+ // expected-note@-2{{while checking the satisfaction}}
+ // expected-note@-3{{in instantiation of requirement}}
+ // expected-note@-4{{while checking the satisfaction}}
+ // expected-note@-6{{while substituting template arguments}}
+ // expected-note@#F3INST{{while checking constraint satisfaction}}
+ // expected-note@#F3INST{{in instantiation of function template specialization}}
+ //
+}
+void f3(T);
+void f3(int);
+
+// Doesn't diagnose, since this is no longer a compound requirement.
+template<typename T> requires (bool(1 && 2))
+void f4(T);
+void f4(int);
+
+void g() {
+ f(0); // #FINST
+ f2(0); // #F2INST
+ f3(0); // #F3INST
+ f4(0);
+}
+
+template<typename T>
+auto Nullptr = nullptr;
+
+template<typename T> concept NullTy = Nullptr<T>;
+// expected-error@-1{{atomic constraint must be of type 'bool' (found }}
+// expected-note@+1{{while checking the satisfaction}}
+static_assert(NullTy<int>);
+
+template<typename T>
+auto Struct = S<T>{};
+
+template<typename T> concept StructTy = Struct<T>;
+// expected-error@-1{{atomic constraint must be of type 'bool' (found 'S<int>')}}
+// expected-note@+1{{while checking the satisfaction}}
+static_assert(StructTy<int>);
Index: clang/lib/Sema/SemaConcept.cpp
===================================================================
--- clang/lib/Sema/SemaConcept.cpp
+++ clang/lib/Sema/SemaConcept.cpp
@@ -329,14 +329,7 @@
Sema::SFINAETrap Trap(S);
SubstitutedExpression =
S.SubstConstraintExpr(const_cast<Expr *>(AtomicExpr), MLTAL);
- // Substitution might have stripped off a contextual conversion to
- // bool if this is the operand of an '&&' or '||'. For example, we
- // might lose an lvalue-to-rvalue conversion here. If so, put it back
- // before we try to evaluate.
- if (SubstitutedExpression.isUsable() &&
- !SubstitutedExpression.isInvalid())
- SubstitutedExpression =
- S.PerformContextuallyConvertToBool(SubstitutedExpression.get());
+
if (SubstitutedExpression.isInvalid() || Trap.hasErrorOccurred()) {
// C++2a [temp.constr.atomic]p1
// ...If substitution results in an invalid type or expression, the
@@ -373,6 +366,22 @@
if (!S.CheckConstraintExpression(SubstitutedExpression.get()))
return ExprError();
+ // [temp.constr.atomic]p3: To determine if an atomic constraint is
+ // satisfied, the parameter mapping and template arguments are first
+ // substituted into its expression. If substitution results in an
+ // invalid type or expression, the constraint is not satisfied.
+ // Otherwise, the lvalue-to-rvalue conversion is performed if necessary,
+ // and E shall be a constant expression of type bool.
+ //
+ // Perform the L to R Value conversion if necessary. We do so for all
+ // non-PRValue categories, else we fail to extend the lifetime of
+ // temporaries, and that fails the constant expression check.
+ if (!SubstitutedExpression.get()->isPRValue())
+ SubstitutedExpression = ImplicitCastExpr::Create(
+ S.Context, SubstitutedExpression.get()->getType(),
+ CK_LValueToRValue, SubstitutedExpression.get(),
+ /*BasePath=*/nullptr, VK_PRValue, FPOptionsOverride());
+
return SubstitutedExpression;
});
}
Index: clang/docs/ReleaseNotes.rst
===================================================================
--- clang/docs/ReleaseNotes.rst
+++ clang/docs/ReleaseNotes.rst
@@ -774,6 +774,9 @@
and `P1975R0: <https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1975r0.html>`_,
which allows parenthesized aggregate-initialization.
+- Fixed an issue with concept requirement evaluation, where we incorrectly allowed implicit
+ conversions to bool for a requirement. This fixes `GH54524 <https://github.com/llvm/llvm-project/issues/54524>`_.
+
C++2b Feature Support
^^^^^^^^^^^^^^^^^^^^^
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