restore code that was actually useful

Author: cor3ntin

clang/lib/Sema/SemaConcept.cpp

@@ -1937,6 +1937,13 @@ void SubstituteParameterMappings::buildParameterMapping(
         static_cast<FoldExpandedConstraint &>(N).getPattern(),
         /*OnlyDeduced=*/false,
         /*Depth=*/0, OccurringIndices);
+  } else if (N.getKind() == NormalizedConstraint::ConstraintKind::ConceptId) {
+    auto *Args = static_cast<ConceptIdConstraint &>(N)
+                     .getConceptId()
+                     ->getTemplateArgsAsWritten();
+    if (Args)
+      SemaRef.MarkUsedTemplateParameters(Args->arguments(),
+                                         /*Depth=*/0, OccurringIndices);
   }
   TemplateArgumentLoc *TempArgs =
       new (SemaRef.Context) TemplateArgumentLoc[OccurringIndices.count()];

clang/test/SemaTemplate/concepts.cpp

@@ -1311,4 +1311,26 @@ static_assert(!E<int>);
 
 }
 
+
+namespace case3 {
+template <class> constexpr bool is_move_constructible_v = false;
+
+template <class _Tp>
+concept __cpp17_move_constructible = is_move_constructible_v<_Tp>; // #is_move_constructible_v
+
+template <class _Tp>
+concept __cpp17_copy_constructible = __cpp17_move_constructible<_Tp>; // #__cpp17_move_constructible
+
+template <class _Iter>
+concept __cpp17_iterator = __cpp17_copy_constructible<_Iter>; // #__cpp17_copy_constructible
+
+struct not_move_constructible {};
+static_assert(__cpp17_iterator<not_move_constructible>); \
+// expected-error {{static assertion failed}} \
+// expected-note {{because 'not_move_constructible' does not satisfy '__cpp17_iterator'}} \
+// expected-note@#__cpp17_copy_constructible {{because 'not_move_constructible' does not satisfy '__cpp17_copy_constructible'}} \
+// expected-note@#__cpp17_move_constructible {{because 'parameter_mapping_regressions::case3::not_move_constructible' does not satisfy '__cpp17_move_constructible'}} \
+// expected-note@#is_move_constructible_v {{because 'is_move_constructible_v<parameter_mapping_regressions::case3::not_move_constructible>' evaluated to false}}
+}
+
 }

clang/test/SemaTemplate/instantiate-template-argument.cpp

@@ -49,7 +49,7 @@ static_assert(foo<char, 'a'>() == 2);
 // expected-error@-1{{no matching function for call to 'foo'}}
 // expected-note@#case1_foo1{{candidate template ignored: constraints not satisfied [with T = char, W = 'a']}}
 // expected-note@#case1_foo1{{because 'C2<char, 'a'>' evaluated to false}}
-// expected-note@#case1_C2{{because 'C1<Y{}, V>' evaluated to false}}
+// expected-note@#case1_C2{{because 'C1<char{}, 'a'>' evaluated to false}}
 // expected-note@#case1_C1{{because 'sizeof ('\x00') >= 4' (1 >= 4) evaluated to false}}
 // expected-note@#case1_foo2{{candidate template ignored: constraints not satisfied [with T = char, X = 'a']}}
 // expected-note@#case1_foo2{{because 'C1<char{}, 'a'>' evaluated to false}}