[clang] 368b683 - [Clang] Implement fix for DR2628

[Roy Jacobson via cfe-commits]

Author: Roy Jacobson
Date: 2022-09-20T00:07:41+03:00
New Revision: 368b6832de33b366d4eb155f940e7476daace6a8

URL: https://github.com/llvm/llvm-project/commit/368b6832de33b366d4eb155f940e7476daace6a8
DIFF: https://github.com/llvm/llvm-project/commit/368b6832de33b366d4eb155f940e7476daace6a8.diff

LOG: [Clang] Implement fix for DR2628

Implement suggested fix for [[ https://cplusplus.github.io/CWG/issues/2628.html | DR2628. ]] Couldn't update the DR docs because there hasn't been a DR index since it was filed, but the tests still run in CI.

Note: I only transfer the constructor constraints, not the struct constraints. I think that's OK because the struct constraints are the same
for all constructors so they don't affect the overload resolution, and if they deduce to something that doesn't pass the constraints
we catch it anyway. So (hopefully) that should be more efficient without sacrificing correctness.

Closes:
https://github.com/llvm/llvm-project/issues/57646
https://github.com/llvm/llvm-project/issues/43829

Reviewed By: erichkeane

Differential Revision: https://reviews.llvm.org/D134145

Added: 
    clang/test/CXX/drs/dr26xx.cpp

Modified: 
    clang/docs/ReleaseNotes.rst
    clang/lib/Sema/SemaTemplate.cpp

Removed: 
    


################################################################################
diff  --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 2546142d2b3d7..96b0c7e363052 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -151,6 +151,10 @@ Bug Fixes
   `Issue 57369 <https://github.com/llvm/llvm-project/issues/57369>`_
   `Issue 57643 <https://github.com/llvm/llvm-project/issues/57643>`_
   `Issue 57793 <https://github.com/llvm/llvm-project/issues/57793>`_
+- Respect constructor constraints during class template argument deduction (CTAD).
+  This is the suggested resolution to CWG DR2628.
+  `Issue 57646 <https://github.com/llvm/llvm-project/issues/57646>`_
+  `Issue 43829 <https://github.com/llvm/llvm-project/issues/43829>`_
 
 
 Improvements to Clang's diagnostics

diff  --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
index e0f913e395771..2ab59e7a37c0d 100644
--- a/clang/lib/Sema/SemaTemplate.cpp
+++ b/clang/lib/Sema/SemaTemplate.cpp
@@ -2445,6 +2445,8 @@ struct ConvertConstructorToDeductionGuideTransform {
                                       TInfo->getType(), TInfo, LocEnd, Ctor);
     Guide->setImplicit();
     Guide->setParams(Params);
+    if (Ctor && Ctor->getTrailingRequiresClause())
+      Guide->setTrailingRequiresClause(Ctor->getTrailingRequiresClause());
 
     for (auto *Param : Params)
       Param->setDeclContext(Guide);

diff  --git a/clang/test/CXX/drs/dr26xx.cpp b/clang/test/CXX/drs/dr26xx.cpp
new file mode 100644
index 0000000000000..1178cefa5bcdf
--- /dev/null
+++ b/clang/test/CXX/drs/dr26xx.cpp
@@ -0,0 +1,16 @@
+// RUN: %clang_cc1 -std=c++20 -triple x86_64-unknown-unknown %s -verify
+
+namespace dr2628 { // dr2628: yes
+
+template <bool A = false, bool B = false>
+struct foo {
+  constexpr foo() requires (!A && !B) = delete; // #DR2628_CTOR
+  constexpr foo() requires (A || B) = delete;
+};
+
+void f() {
+  foo fooable; // expected-error {{call to deleted}}
+  // expected-note@#DR2628_CTOR {{marked deleted here}}
+}
+
+}