https://github.com/jessding updated https://github.com/llvm/llvm-project/pull/201441
>From 6d0ac443e9fa162908117b6de54748ed00d10d02 Mon Sep 17 00:00:00 2001 From: Jess Ding <[email protected]> Date: Wed, 3 Jun 2026 14:36:01 -0400 Subject: [PATCH 1/7] add test verifying DR242 behavior --- clang/test/CXX/drs/cwg2xx.cpp | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) diff --git a/clang/test/CXX/drs/cwg2xx.cpp b/clang/test/CXX/drs/cwg2xx.cpp index f81ab02e7d748..2ca9a84d0a03a 100644 --- a/clang/test/CXX/drs/cwg2xx.cpp +++ b/clang/test/CXX/drs/cwg2xx.cpp @@ -695,6 +695,37 @@ namespace cwg241 { // cwg241: 9 } } // namespace cwg241 +namespace cwg242 { // cwg242: yes + struct A {}; + struct I1 : A {}; + struct I2 : A {}; + struct D : I1, I2 {}; + + A *upcast(D *p) { + return (A *)(p); + /* expected-error@-1 + {{ambiguous conversion from derived class 'D' to base class 'A': + struct cwg242::D -> I1 -> A + struct cwg242::D -> I2 -> A}}*/ + } + + D *downcast(A *p) { + return (D *)(p); + /* expected-error@-1 + {{ambiguous cast from base 'cwg242::A' to derived 'cwg242::D': + A -> I1 -> struct cwg242::D + A -> I2 -> struct cwg242::D}}*/ + } + + struct V {}; + struct B : virtual V {}; + + B *virt_downcast(V *p) { + return (B *)(p); + // expected-error@-1 {{cannot cast 'cwg242::V *' to 'B *' via virtual base 'cwg242::V'}} + } +} // namespace cwg242 + namespace cwg243 { // cwg243: 2.8 struct B; struct A { >From 00ae8200b17f9881d771cf20f7909cc2df4c4251 Mon Sep 17 00:00:00 2001 From: jessding <[email protected]> Date: Sat, 6 Jun 2026 16:06:54 -0400 Subject: [PATCH 2/7] Update earliest known clang defect resolution availability to 2.8 --- clang/test/CXX/drs/cwg2xx.cpp | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/clang/test/CXX/drs/cwg2xx.cpp b/clang/test/CXX/drs/cwg2xx.cpp index 2ca9a84d0a03a..7568630e41dfe 100644 --- a/clang/test/CXX/drs/cwg2xx.cpp +++ b/clang/test/CXX/drs/cwg2xx.cpp @@ -695,7 +695,7 @@ namespace cwg241 { // cwg241: 9 } } // namespace cwg241 -namespace cwg242 { // cwg242: yes +namespace cwg242 { // cwg242: 2.8 struct A {}; struct I1 : A {}; struct I2 : A {}; >From c6701dfcd05091e10bd1c1d55bd8862841dec4d1 Mon Sep 17 00:00:00 2001 From: jessding <[email protected]> Date: Sat, 6 Jun 2026 16:27:37 -0400 Subject: [PATCH 3/7] update expected error strings --- clang/test/CXX/drs/cwg2xx.cpp | 10 ++-------- 1 file changed, 2 insertions(+), 8 deletions(-) diff --git a/clang/test/CXX/drs/cwg2xx.cpp b/clang/test/CXX/drs/cwg2xx.cpp index 7568630e41dfe..30a38ac431caa 100644 --- a/clang/test/CXX/drs/cwg2xx.cpp +++ b/clang/test/CXX/drs/cwg2xx.cpp @@ -703,18 +703,12 @@ namespace cwg242 { // cwg242: 2.8 A *upcast(D *p) { return (A *)(p); - /* expected-error@-1 - {{ambiguous conversion from derived class 'D' to base class 'A': - struct cwg242::D -> I1 -> A - struct cwg242::D -> I2 -> A}}*/ + // expected-error@-1 {{error: ambiguous conversion from derived class 'cwg242::D' to base class 'cwg242::A'}} } D *downcast(A *p) { return (D *)(p); - /* expected-error@-1 - {{ambiguous cast from base 'cwg242::A' to derived 'cwg242::D': - A -> I1 -> struct cwg242::D - A -> I2 -> struct cwg242::D}}*/ + // expected-error@-1 {{ambiguous cast from base 'cwg242::A' to derived 'cwg242::D'}} } struct V {}; >From 6b0a08a7c8bb371b23f35cdbf82accfb53d7c34b Mon Sep 17 00:00:00 2001 From: jessding <[email protected]> Date: Sat, 6 Jun 2026 16:32:01 -0400 Subject: [PATCH 4/7] add reference cast and pointer-to-member conversion tests --- clang/test/CXX/drs/cwg2xx.cpp | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/clang/test/CXX/drs/cwg2xx.cpp b/clang/test/CXX/drs/cwg2xx.cpp index 30a38ac431caa..75a0573c05fab 100644 --- a/clang/test/CXX/drs/cwg2xx.cpp +++ b/clang/test/CXX/drs/cwg2xx.cpp @@ -718,6 +718,16 @@ namespace cwg242 { // cwg242: 2.8 return (B *)(p); // expected-error@-1 {{cannot cast 'cwg242::V *' to 'B *' via virtual base 'cwg242::V'}} } + + A &ref_upcast(D &r) { + return (A &)(r); + // expected-error@-1 {{ambiguous conversion from derived class 'cwg242::D' to base class 'cwg242::A'}} + } + + int D::*ptm_cast(int A::*p) { + return (int D::*)(p); + // expected-error@-1 {{ambiguous conversion from pointer to member of base class 'cwg242::A' to pointer to member of derived class 'cwg242::D'}} + } } // namespace cwg242 namespace cwg243 { // cwg243: 2.8 >From fa538d83f2e8c77571bca5581608b1a199f8b55b Mon Sep 17 00:00:00 2001 From: jessding <[email protected]> Date: Mon, 22 Jun 2026 22:48:23 -0400 Subject: [PATCH 5/7] add reference downcast test --- clang/test/CXX/drs/cwg2xx.cpp | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/clang/test/CXX/drs/cwg2xx.cpp b/clang/test/CXX/drs/cwg2xx.cpp index 75a0573c05fab..833a9ff48ade0 100644 --- a/clang/test/CXX/drs/cwg2xx.cpp +++ b/clang/test/CXX/drs/cwg2xx.cpp @@ -724,6 +724,11 @@ namespace cwg242 { // cwg242: 2.8 // expected-error@-1 {{ambiguous conversion from derived class 'cwg242::D' to base class 'cwg242::A'}} } + D &ref_downcast(A &r) { + return (D &)(r); + // expected-error@-1 {{ambiguous cast from base 'cwg242::A' to derived 'cwg242::D'}} + } + int D::*ptm_cast(int A::*p) { return (int D::*)(p); // expected-error@-1 {{ambiguous conversion from pointer to member of base class 'cwg242::A' to pointer to member of derived class 'cwg242::D'}} >From 13e056b710030ca2edfd55b9cc79a215feb5c0f2 Mon Sep 17 00:00:00 2001 From: jessding <[email protected]> Date: Mon, 22 Jun 2026 22:48:42 -0400 Subject: [PATCH 6/7] update DR status page --- clang/www/cxx_dr_status.html | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/clang/www/cxx_dr_status.html b/clang/www/cxx_dr_status.html index c9f136ba26681..379e0f80b990f 100755 --- a/clang/www/cxx_dr_status.html +++ b/clang/www/cxx_dr_status.html @@ -1740,7 +1740,7 @@ <h2 id="cxxdr">C++ defect report implementation status</h2> <td>[<a href="https://wg21.link/expr.cast";>expr.cast</a>]</td> <td>CD4</td> <td>Interpretation of old-style casts</td> - <td class="unknown" align="center">Unknown</td> + <td class="full" align="center">Clang 2.8</td> </tr> <tr id="243"> <td><a href="https://cplusplus.github.io/CWG/issues/243.html";>243</a></td> >From e84834fbdf95b3da6ad3030bee929fa7d9ae1e78 Mon Sep 17 00:00:00 2001 From: jessding <[email protected]> Date: Tue, 23 Jun 2026 00:00:42 -0400 Subject: [PATCH 7/7] add qual up/downcast test cases, and update earliest supporting clang version from 2.8 to 3.0 --- clang/test/CXX/drs/cwg2xx.cpp | 43 ++++++++++++++++++++++++++++++----- clang/www/cxx_dr_status.html | 2 +- 2 files changed, 38 insertions(+), 7 deletions(-) diff --git a/clang/test/CXX/drs/cwg2xx.cpp b/clang/test/CXX/drs/cwg2xx.cpp index 833a9ff48ade0..cc95f55892f7e 100644 --- a/clang/test/CXX/drs/cwg2xx.cpp +++ b/clang/test/CXX/drs/cwg2xx.cpp @@ -695,7 +695,7 @@ namespace cwg241 { // cwg241: 9 } } // namespace cwg241 -namespace cwg242 { // cwg242: 2.8 +namespace cwg242 { // cwg242: 3.0 struct A {}; struct I1 : A {}; struct I2 : A {}; @@ -703,12 +703,18 @@ namespace cwg242 { // cwg242: 2.8 A *upcast(D *p) { return (A *)(p); - // expected-error@-1 {{error: ambiguous conversion from derived class 'cwg242::D' to base class 'cwg242::A'}} + /* expected-error@-1 + {{ambiguous conversion from derived class 'D' to base class 'A': + struct cwg242::D -> I1 -> A + struct cwg242::D -> I2 -> A}}*/ } D *downcast(A *p) { return (D *)(p); - // expected-error@-1 {{ambiguous cast from base 'cwg242::A' to derived 'cwg242::D'}} + /* expected-error@-1 + {{ambiguous cast from base 'cwg242::A' to derived 'cwg242::D': + A -> I1 -> struct cwg242::D + A -> I2 -> struct cwg242::D}}*/ } struct V {}; @@ -721,17 +727,42 @@ namespace cwg242 { // cwg242: 2.8 A &ref_upcast(D &r) { return (A &)(r); - // expected-error@-1 {{ambiguous conversion from derived class 'cwg242::D' to base class 'cwg242::A'}} + /* expected-error@-1 + {{ambiguous conversion from derived class 'D' to base class 'A': + struct cwg242::D -> I1 -> A + struct cwg242::D -> I2 -> A}}*/ } D &ref_downcast(A &r) { return (D &)(r); - // expected-error@-1 {{ambiguous cast from base 'cwg242::A' to derived 'cwg242::D'}} + /* expected-error@-1 + {{ambiguous cast from base 'cwg242::A' to derived 'cwg242::D': + A -> I1 -> struct cwg242::D + A -> I2 -> struct cwg242::D}}*/ + } + + A *qual_upcast(const D *p) { + return (A *)(p); + /* expected-error@-1 + {{ambiguous conversion from derived class 'D' to base class 'A': + struct cwg242::D -> I1 -> A + struct cwg242::D -> I2 -> A}}*/ + } + + D *qual_downcast(const A *p) { + return (D *)(p); + /* expected-error@-1 + {{ambiguous cast from base 'cwg242::A' to derived 'cwg242::D': + A -> I1 -> struct cwg242::D + A -> I2 -> struct cwg242::D}}*/ } int D::*ptm_cast(int A::*p) { return (int D::*)(p); - // expected-error@-1 {{ambiguous conversion from pointer to member of base class 'cwg242::A' to pointer to member of derived class 'cwg242::D'}} + /* expected-error@-1 + {{ambiguous conversion from pointer to member of base class 'A' to pointer to member of derived class 'D': + struct cwg242::D -> I1 -> A + struct cwg242::D -> I2 -> A}}*/ } } // namespace cwg242 diff --git a/clang/www/cxx_dr_status.html b/clang/www/cxx_dr_status.html index 379e0f80b990f..71a3438e5c592 100755 --- a/clang/www/cxx_dr_status.html +++ b/clang/www/cxx_dr_status.html @@ -1740,7 +1740,7 @@ <h2 id="cxxdr">C++ defect report implementation status</h2> <td>[<a href="https://wg21.link/expr.cast";>expr.cast</a>]</td> <td>CD4</td> <td>Interpretation of old-style casts</td> - <td class="full" align="center">Clang 2.8</td> + <td class="full" align="center">Clang 3.0</td> </tr> <tr id="243"> <td><a href="https://cplusplus.github.io/CWG/issues/243.html";>243</a></td> _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
