[clang] 64e8d5b - [clang] Add tests from CWG156 to CWG1111 (dual-scope lookup for conversion-function-ids) (#121654)
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Sun Jan 5 03:49:59 PST 2025
Author: Vlad Serebrennikov
Date: 2025-01-05T15:49:55+04:00
New Revision: 64e8d5b1baaa478c40931d290bf30687a6c93dac
URL: https://github.com/llvm/llvm-project/commit/64e8d5b1baaa478c40931d290bf30687a6c93dac
DIFF: https://github.com/llvm/llvm-project/commit/64e8d5b1baaa478c40931d290bf30687a6c93dac.diff
LOG: [clang] Add tests from CWG156 to CWG1111 (dual-scope lookup for conversion-function-ids) (#121654)
This patch adds test from
[CWG156](https://cplusplus.github.io/CWG/issues/156.html) to
[CWG1111](https://cplusplus.github.io/CWG/issues/1111.html) test, and
downgrades the latter to partial availability. The most relevant piece
of current wording is
[[basic.lookup.unqual]/5](https://eel.is/c++draft/basic.lookup#unqual-5):
> An unqualified name that is a component name
([[expr.prim.id.unqual]](https://eel.is/c++draft/expr.prim.id.unqual))
of a
[type-specifier](https://eel.is/c++draft/dcl.type.general#nt:type-specifier)
or
[ptr-operator](https://eel.is/c++draft/dcl.decl.general#nt:ptr-operator)
of a
[conversion-type-id](https://eel.is/c++draft/class.conv.fct#nt:conversion-type-id)
is looked up in the same fashion as the
[conversion-function-id](https://eel.is/c++draft/class.conv.fct#nt:conversion-function-id)
in which it
appears[.](https://eel.is/c++draft/basic.lookup#unqual-5.sentence-1)
If that lookup finds nothing, it undergoes unqualified name lookup; in
each case, only names that denote types or templates whose
specializations are types are
considered[.](https://eel.is/c++draft/basic.lookup#unqual-5.sentence-2)
Per resolution of
[CWG1111](https://cplusplus.github.io/CWG/issues/1111.html), additional
lookup in the context of the entire postfix-expression, which originally
was intended to cross-check lookup in the context of object-expression,
was effectively turned into a fallback for it.
Check out "Calling a conversion function" example in
[P1787R6](https://wg21.link/p1787r6) for step-by-step explanation of the
current lookup mechanics for conversion functions.
Clang rejects one of the well-formed examples, hence partial status.
Clang is the only implementation which rejects it:
https://godbolt.org/z/ohhbx8Mfs
Added:
Modified:
clang/test/CXX/drs/cwg11xx.cpp
clang/test/CXX/drs/cwg1xx.cpp
clang/www/cxx_dr_status.html
Removed:
################################################################################
diff --git a/clang/test/CXX/drs/cwg11xx.cpp b/clang/test/CXX/drs/cwg11xx.cpp
index 8d187041400a60..d33ff060d2d39e 100644
--- a/clang/test/CXX/drs/cwg11xx.cpp
+++ b/clang/test/CXX/drs/cwg11xx.cpp
@@ -19,7 +19,7 @@ decltype(return_T<B<int>>())* b;
#endif
} // namespace cwg1110
-namespace cwg1111 { // cwg1111: 3.2
+namespace cwg1111 { // cwg1111: partial
namespace example1 {
template <typename> struct set; // #cwg1111-struct-set
@@ -57,6 +57,48 @@ void baz() {
a.operator A();
}
} // namespace example2
+
+namespace example3 {
+struct A {
+ operator int();
+} a;
+void foo() {
+ typedef int T;
+ a.operator T(); // T is found using unqualified lookup
+ // after qualified lookup in A fails.
+}
+} // namespace example3
+
+namespace example4 {
+struct A {
+ typedef int T; // #cwg1111-A-T
+ operator T();
+};
+struct B : A {
+ operator T();
+} b;
+void foo() {
+ b.A::operator T(); // FIXME: qualified lookup should find T in A.
+ // expected-error at -1 {{unknown type name 'T'}}
+ // expected-note@#cwg1111-A-T {{'A::T' declared here}}
+}
+} // namespace example4
+
+namespace example5 {
+template <class T1> struct A {
+ operator T1();
+};
+template <class T2> struct B : A<T2> {
+ operator T2();
+ void foo() {
+ // In both cases, during instantiation, qualified lookup for T2 wouldn't be able
+ // to find anything, so T2 has to be found by unqualified lookup.
+ // After that, 'operator T2()' is found in A<T2> by qualfied lookup.
+ T2 a = A<T2>::operator T2();
+ T2 b = ((A<T2> *)this)->operator T2();
+ }
+};
+} // namespace example5
} // namespace cwg1111
namespace cwg1113 { // cwg1113: partial
diff --git a/clang/test/CXX/drs/cwg1xx.cpp b/clang/test/CXX/drs/cwg1xx.cpp
index 9eeca4cb2a681a..e8fe3fff43a575 100644
--- a/clang/test/CXX/drs/cwg1xx.cpp
+++ b/clang/test/CXX/drs/cwg1xx.cpp
@@ -922,6 +922,7 @@ namespace cwg155 { // cwg155: dup 632
// expected-warning at -1 {{braces around scalar initializer}}
}
+// cwg156: sup 1111
// cwg158 is in cwg158.cpp
namespace cwg159 { // cwg159: 3.5
diff --git a/clang/www/cxx_dr_status.html b/clang/www/cxx_dr_status.html
index d767d2973b57ef..6ed5e3d37bae79 100755
--- a/clang/www/cxx_dr_status.html
+++ b/clang/www/cxx_dr_status.html
@@ -981,7 +981,7 @@ <h2 id="cxxdr">C++ defect report implementation status</h2>
<td><a href="https://cplusplus.github.io/CWG/issues/156.html">156</a></td>
<td>NAD</td>
<td>Name lookup for conversion functions</td>
- <td class="unknown" align="center">Unknown</td>
+ <td class="partial-superseded" align="center">Superseded by <a href="#1111">1111</a></td>
</tr>
<tr class="open" id="157">
<td><a href="https://cplusplus.github.io/CWG/issues/157.html">157</a></td>
@@ -6485,7 +6485,7 @@ <h2 id="cxxdr">C++ defect report implementation status</h2>
<td><a href="https://cplusplus.github.io/CWG/issues/1111.html">1111</a></td>
<td>C++11</td>
<td>Remove dual-scope lookup of member template names</td>
- <td class="full" align="center">Clang 3.2</td>
+ <td class="partial" align="center">Partial</td>
</tr>
<tr id="1112">
<td><a href="https://cplusplus.github.io/CWG/issues/1112.html">1112</a></td>
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