[PATCH] D146140: [clang] Properly parse variable template requires clause in lambda

[Emilia Dreamer via Phabricator via cfe-commits]

This revision was landed with ongoing or failed builds.
This revision was automatically updated to reflect the committed changes.
Closed by commit rG6acdf58919d5: [clang] Properly parse variable template requires clause in lambda (authored by rymiel).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D146140/new/

https://reviews.llvm.org/D146140

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


Index: clang/test/SemaTemplate/concepts.cpp
===================================================================
--- clang/test/SemaTemplate/concepts.cpp
+++ clang/test/SemaTemplate/concepts.cpp
@@ -55,10 +55,15 @@
 }
 
 namespace P0857R0 {
+  template <typename T> static constexpr bool V = true;
+
   void f() {
     auto x = []<bool B> requires B {}; // expected-note {{constraints not satisfied}} expected-note {{false}}
     x.operator()<true>();
     x.operator()<false>(); // expected-error {{no matching member function}}
+
+    auto y = []<typename T> requires V<T> () {};
+    y.operator()<int>(); // OK
   }
 
   template<typename T> concept C = true;
Index: clang/lib/Sema/SemaConcept.cpp
===================================================================
--- clang/lib/Sema/SemaConcept.cpp
+++ clang/lib/Sema/SemaConcept.cpp
@@ -105,27 +105,35 @@
   QualType Type = ConstraintExpression->getType();
 
   auto CheckForNonPrimary = [&] {
-    if (PossibleNonPrimary)
-      *PossibleNonPrimary =
-          // We have the following case:
-          // template<typename> requires func(0) struct S { };
-          // The user probably isn't aware of the parentheses required around
-          // the function call, and we're only going to parse 'func' as the
-          // primary-expression, and complain that it is of non-bool type.
-          (NextToken.is(tok::l_paren) &&
-           (IsTrailingRequiresClause ||
-            (Type->isDependentType() &&
-             isa<UnresolvedLookupExpr>(ConstraintExpression)) ||
-            Type->isFunctionType() ||
-            Type->isSpecificBuiltinType(BuiltinType::Overload))) ||
-          // We have the following case:
-          // template<typename T> requires size_<T> == 0 struct S { };
-          // The user probably isn't aware of the parentheses required around
-          // the binary operator, and we're only going to parse 'func' as the
-          // first operand, and complain that it is of non-bool type.
-          getBinOpPrecedence(NextToken.getKind(),
-                             /*GreaterThanIsOperator=*/true,
-                             getLangOpts().CPlusPlus11) > prec::LogicalAnd;
+    if (!PossibleNonPrimary)
+      return;
+
+    *PossibleNonPrimary =
+        // We have the following case:
+        // template<typename> requires func(0) struct S { };
+        // The user probably isn't aware of the parentheses required around
+        // the function call, and we're only going to parse 'func' as the
+        // primary-expression, and complain that it is of non-bool type.
+        //
+        // However, if we're in a lambda, this might also be:
+        // []<typename> requires var () {};
+        // Which also looks like a function call due to the lambda parentheses,
+        // but unlike the first case, isn't an error, so this check is skipped.
+        (NextToken.is(tok::l_paren) &&
+         (IsTrailingRequiresClause ||
+          (Type->isDependentType() &&
+           isa<UnresolvedLookupExpr>(ConstraintExpression) &&
+           !dyn_cast_if_present<LambdaScopeInfo>(getCurFunction())) ||
+          Type->isFunctionType() ||
+          Type->isSpecificBuiltinType(BuiltinType::Overload))) ||
+        // We have the following case:
+        // template<typename T> requires size_<T> == 0 struct S { };
+        // The user probably isn't aware of the parentheses required around
+        // the binary operator, and we're only going to parse 'func' as the
+        // first operand, and complain that it is of non-bool type.
+        getBinOpPrecedence(NextToken.getKind(),
+                           /*GreaterThanIsOperator=*/true,
+                           getLangOpts().CPlusPlus11) > prec::LogicalAnd;
   };
 
   // An atomic constraint!
Index: clang/docs/ReleaseNotes.rst
===================================================================
--- clang/docs/ReleaseNotes.rst
+++ clang/docs/ReleaseNotes.rst
@@ -80,6 +80,9 @@
 ^^^^^^^^^^^^^^^^^^^^^
 - Support for out-of-line definitions of constrained templates has been improved.
   This partially fixes `#49620 <https://github.com/llvm/llvm-project/issues/49620>`_.
+- Lambda templates with a requires clause directly after the template parameters now parse
+  correctly if the requires clause consists of a variable with a dependent type.
+  (`#61278 <https://github.com/llvm/llvm-project/issues/61278>`_)
 
 C++2b Feature Support
 ^^^^^^^^^^^^^^^^^^^^^


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