[PATCH] D122083: [Concepts] Fix placeholder constraints when references are involved

[Roy Jacobson via Phabricator via cfe-commits]

royjacobson updated this revision to Diff 417618.
royjacobson added a comment.

Added release notes.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D122083/new/

https://reviews.llvm.org/D122083

Files:
  clang/docs/ReleaseNotes.rst
  clang/lib/Sema/SemaTemplateDeduction.cpp
  clang/test/SemaTemplate/concepts.cpp


Index: clang/test/SemaTemplate/concepts.cpp
===================================================================
--- clang/test/SemaTemplate/concepts.cpp
+++ clang/test/SemaTemplate/concepts.cpp
@@ -171,7 +171,7 @@
 }
 
 namespace PR49188 {
-  template<class T> concept C = false;     // expected-note 6 {{because 'false' evaluated to false}}
+  template<class T> concept C = false;     // expected-note 7 {{because 'false' evaluated to false}}
 
   C auto f1() { // expected-error {{deduced type 'void' does not satisfy 'C'}}
     return void();
@@ -189,7 +189,7 @@
   }
   C decltype(auto) f6() { // expected-error {{deduced type 'void' does not satisfy 'C'}}
   }
-  C auto& f7() { // expected-error {{cannot form a reference to 'void'}}
+  C auto& f7() { // expected-error {{deduced type 'void' does not satisfy 'C'}}
     return void();
   }
   C auto& f8() {
@@ -199,13 +199,16 @@
   }
 }
 namespace PR53911 {
-  template<class T> concept C = false;
+  template<class T> concept C = false; // expected-note 3 {{because 'false' evaluated to false}}
 
-  C auto *f1() {
-    return (void*)nullptr; // FIXME: should error
+  C auto *f1() { // expected-error {{deduced type 'void' does not satisfy 'C'}}
+    return (void*)nullptr;
   }
-  C auto *f2() {
-    return (int*)nullptr; // FIXME: should error
+  C auto *f2() { // expected-error {{deduced type 'int' does not satisfy 'C'}}
+    return (int*)nullptr;
+  }
+  C auto *****f3() { // expected-error {{deduced type 'int' does not satisfy 'C'}}
+    return (int*****)nullptr;
   }
 }
 
@@ -222,3 +225,34 @@
 };
 void (*f2)() = B::f; // expected-error {{address of overloaded function 'f' does not match required type}}
 }
+
+namespace PR54443 {
+
+template <class T, class U>
+struct is_same { static constexpr bool value = false; };
+
+template <class T>
+struct is_same<T, T> { static constexpr bool value = true; };
+
+template <class T, class U>
+concept same_as = is_same<T, U>::value; // expected-note-re 4 {{because {{.*}} evaluated to false}}
+
+int const &f();
+
+same_as<int const> auto i1 = f(); // expected-error {{deduced type 'int' does not satisfy 'same_as<const int>'}}
+same_as<int const> auto &i2 = f();
+same_as<int const> auto &&i3 = f(); // expected-error {{deduced type 'const int &' does not satisfy 'same_as<const int>'}}
+
+same_as<int const &> auto i4 = f(); // expected-error {{deduced type 'int' does not satisfy 'same_as<const int &>'}}
+same_as<int const &> auto &i5 = f(); // expected-error {{deduced type 'const int' does not satisfy 'same_as<const int &>'}}
+same_as<int const &> auto &&i6 = f();
+
+template <class T>
+concept C = false; // expected-note 3 {{because 'false' evaluated to false}}
+
+int **const &g();
+
+C auto **j1 = g();   // expected-error {{deduced type 'int' does not satisfy 'C'}}
+C auto **&j2 = g();  // expected-error {{deduced type 'int' does not satisfy 'C'}}
+C auto **&&j3 = g(); // expected-error {{deduced type 'int' does not satisfy 'C'}}
+}
Index: clang/lib/Sema/SemaTemplateDeduction.cpp
===================================================================
--- clang/lib/Sema/SemaTemplateDeduction.cpp
+++ clang/lib/Sema/SemaTemplateDeduction.cpp
@@ -4769,12 +4769,13 @@
       return DAR_FailedAlreadyDiagnosed;
   }
 
-  if (const auto *AT = Type.getType()->getAs<AutoType>()) {
+  QualType MaybeAuto = Type.getType().getNonReferenceType();
+  while (MaybeAuto->isPointerType())
+    MaybeAuto = MaybeAuto->getPointeeType();
+  if (const auto *AT = MaybeAuto->getAs<AutoType>()) {
     if (AT->isConstrained() && !IgnoreConstraints) {
-      auto ConstraintsResult =
-          CheckDeducedPlaceholderConstraints(*this, *AT,
-                                             Type.getContainedAutoTypeLoc(),
-                                             DeducedType);
+      auto ConstraintsResult = CheckDeducedPlaceholderConstraints(
+          *this, *AT, Type.getContainedAutoTypeLoc(), DeducedType);
       if (ConstraintsResult != DAR_Succeeded)
         return ConstraintsResult;
     }
Index: clang/docs/ReleaseNotes.rst
===================================================================
--- clang/docs/ReleaseNotes.rst
+++ clang/docs/ReleaseNotes.rst
@@ -61,6 +61,10 @@
   size expression. This was fixed and ``::getArraySize()`` will now always
   either return ``None`` or a ``llvm::Optional`` wrapping a valid ``Expr*``.
   This fixes `Issue 53742 <https://github.com/llvm/llvm-project/issues/53742>`_.
+- Placeholder constraints, as in `Concept auto x = f();`, were not checked when modifiers
+  like ``auto&`` or ``auto**`` were added. These constraints are now checked.
+  This fixes  `Issue 53911 <https://github.com/llvm/llvm-project/issues/53911>`_
+  and  `Issue 54443 <https://github.com/llvm/llvm-project/issues/54443>`_.
 
 Improvements to Clang's diagnostics
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

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