[Clang][Sema] Substitute constraints only for declarations with different lexical...

Substitute constraints only for declarations with different lexical contexts.
This results in avoiding the substitution of constraints during the redeclaration check
inside a class (and by product caching the wrong substitution result).

Test plan: ninja check-all

Differential revision: https://reviews.llvm.org/D150730

diff --git a/clang/lib/Sema/SemaConcept.cpp b/clang/lib/Sema/SemaConcept.cpp
index 1126c2c..2f5fb8f 100644 (file)
--- a/clang/lib/Sema/SemaConcept.cpp
+++ b/clang/lib/Sema/SemaConcept.cpp
@@ -780,7 +780,9 @@ bool Sema::AreConstraintExpressionsEqual(const NamedDecl *Old,
                                          const Expr *NewConstr) {
   if (OldConstr == NewConstr)
     return true;
-  if (Old && New && Old != New) {
+  // C++ [temp.constr.decl]p4
+  if (Old && New && Old != New &&
+      Old->getLexicalDeclContext() != New->getLexicalDeclContext()) {
     if (const Expr *SubstConstr =
             SubstituteConstraintExpression(*this, Old, OldConstr))
       OldConstr = SubstConstr;

diff --git a/clang/test/SemaTemplate/concepts-no-early-substitution.cpp b/clang/test/SemaTemplate/concepts-no-early-substitution.cpp
new file mode 100644 (file)
index 0000000..9e576f1
--- /dev/null
+++ b/clang/test/SemaTemplate/concepts-no-early-substitution.cpp
@@ -0,0 +1,33 @@
+// RUN: %clang_cc1 -std=c++20 -x c++ %s -verify -fsyntax-only
+// expected-no-diagnostics
+
+template <typename T0>
+concept HasMemberBegin = requires(T0 t) { t.begin(); };
+
+struct GetBegin {
+  template <HasMemberBegin T1>
+  void operator()(T1);
+};
+
+GetBegin begin;
+
+template <typename T2>
+concept Concept = requires(T2 t) { begin(t); };
+
+struct Subrange;
+
+template <typename T3>
+struct View {
+  Subrange &getSubrange();
+
+  operator bool()
+    requires true;
+
+  operator bool()
+    requires requires { begin(getSubrange()); };
+
+  void begin();
+};
+
+struct Subrange : View<void> {};
+static_assert(Concept<Subrange>);