[clang] 1e3a1ce - Add tests for CWG issues 6, 212, 232, 2823. (#165633)
via cfe-commits
cfe-commits at lists.llvm.org
Thu Oct 30 15:50:49 PDT 2025
Author: Richard Smith
Date: 2025-10-30T15:50:45-07:00
New Revision: 1e3a1ce911d1e5e3804b63e3ba3059c36eb697e5
URL: https://github.com/llvm/llvm-project/commit/1e3a1ce911d1e5e3804b63e3ba3059c36eb697e5
DIFF: https://github.com/llvm/llvm-project/commit/1e3a1ce911d1e5e3804b63e3ba3059c36eb697e5.diff
LOG: Add tests for CWG issues 6, 212, 232, 2823. (#165633)
Unfortunately this adds two more "no"s to cxx_dr_status for 232 and
2823.
---------
Co-authored-by: Vlad Serebrennikov <serebrennikov.vladislav at gmail.com>
Added:
clang/test/CXX/drs/cwg6.cpp
Modified:
clang/test/CXX/drs/cwg0xx.cpp
clang/test/CXX/drs/cwg28xx.cpp
clang/test/CXX/drs/cwg2xx.cpp
clang/www/cxx_dr_status.html
Removed:
################################################################################
diff --git a/clang/test/CXX/drs/cwg0xx.cpp b/clang/test/CXX/drs/cwg0xx.cpp
index 805be67f2dc1a..10a4f1d6add3a 100644
--- a/clang/test/CXX/drs/cwg0xx.cpp
+++ b/clang/test/CXX/drs/cwg0xx.cpp
@@ -90,6 +90,8 @@ namespace cwg5 { // cwg5: 3.1
const C c = e;
} // namespace cwg5
+// cwg6 is in cwg6.cpp
+
namespace cwg7 { // cwg7: 3.4
class A { public: ~A(); };
class B : virtual private A {}; // #cwg7-B
diff --git a/clang/test/CXX/drs/cwg28xx.cpp b/clang/test/CXX/drs/cwg28xx.cpp
index a6b2b99e0c3f1..d0ee191ef23d8 100644
--- a/clang/test/CXX/drs/cwg28xx.cpp
+++ b/clang/test/CXX/drs/cwg28xx.cpp
@@ -61,6 +61,24 @@ namespace cwg2819 { // cwg2819: 19 c++26
#endif
} // namespace cwg2819
+namespace cwg2823 { // cwg2823: no
+#if __cplusplus >= 201103L
+ constexpr int *p = 0;
+ constexpr int *q1 = &*p;
+ // expected-error at -1 {{constexpr variable 'q1' must be initialized by a constant expression}}
+ // expected-note at -2 {{dereferencing a null pointer is not allowed in a constant expression}}
+ // FIXME: invalid: dereferencing a null pointer.
+ constexpr int *q2 = &p[0];
+
+ int arr[32];
+ constexpr int *r = arr;
+ // FIXME: invalid: dereferencing a past-the-end pointer.
+ constexpr int *s1 = &*(r + 32);
+ // FIXME: invalid: dereferencing a past-the-end pointer.
+ constexpr int *s2 = &r[32];
+#endif
+}
+
namespace cwg2847 { // cwg2847: 19 review 2024-03-01
#if __cplusplus >= 202002L
diff --git a/clang/test/CXX/drs/cwg2xx.cpp b/clang/test/CXX/drs/cwg2xx.cpp
index 37186e3c3f205..a4995ddc2c588 100644
--- a/clang/test/CXX/drs/cwg2xx.cpp
+++ b/clang/test/CXX/drs/cwg2xx.cpp
@@ -230,6 +230,38 @@ namespace cwg211 { // cwg211: 2.7
};
} // namespace cwg211
+namespace cwg212 { // cwg212: 2.7
+ template<typename T> struct Base;
+ template<typename T> struct Derived;
+
+ int *overload(void*);
+ float *overload(Base<int>*);
+ double *overload(Base<long>*);
+
+ void f(Derived<int> *p) {
+ // OK, calls void* overload.
+ int *a = overload(p);
+
+ Base<int> *q = p;
+ // expected-error at -1 {{cannot initialize a variable of type 'Base<int> *' with an lvalue of type 'Derived<int> *'}}
+ }
+
+ template<typename T> struct Base {};
+ template<typename T> struct Derived : Base<T> {};
+
+ void g(Derived<long> *p) {
+ // OK, instantiates and calls Base<long>* overlod.
+ double *b = overload(p);
+ (void)b;
+ }
+
+ void h(Derived<float> *p) {
+ // OK, instantiates and converts.
+ Base<float> *q = p;
+ (void)q;
+ }
+}
+
namespace cwg213 { // cwg213: 2.7
template <class T> struct A : T {
void h(T t) {
@@ -593,6 +625,9 @@ namespace cwg231 { // cwg231: 2.7
}
} // namespace cwg231
+// 232 is NAD; the desired behavior is described in 2823.
+// cwg232: dup 2823
+
// cwg234: na
// cwg235: na
diff --git a/clang/test/CXX/drs/cwg6.cpp b/clang/test/CXX/drs/cwg6.cpp
new file mode 100644
index 0000000000000..4752e72034c78
--- /dev/null
+++ b/clang/test/CXX/drs/cwg6.cpp
@@ -0,0 +1,51 @@
+// RUN: %clang_cc1 -std=c++98 %s -triple x86_64-linux-gnu -emit-llvm -o - -fexceptions -fcxx-exceptions -pedantic-errors | FileCheck %s --check-prefixes CHECK
+// RUN: %clang_cc1 -std=c++11 %s -triple x86_64-linux-gnu -emit-llvm -o - -fexceptions -fcxx-exceptions -pedantic-errors | FileCheck %s --check-prefixes CHECK
+// RUN: %clang_cc1 -std=c++14 %s -triple x86_64-linux-gnu -emit-llvm -o - -fexceptions -fcxx-exceptions -pedantic-errors | FileCheck %s --check-prefixes CHECK
+// RUN: %clang_cc1 -std=c++17 %s -triple x86_64-linux-gnu -emit-llvm -o - -fexceptions -fcxx-exceptions -pedantic-errors | FileCheck %s --check-prefixes CHECK
+// RUN: %clang_cc1 -std=c++20 %s -triple x86_64-linux-gnu -emit-llvm -o - -fexceptions -fcxx-exceptions -pedantic-errors | FileCheck %s --check-prefixes CHECK
+// RUN: %clang_cc1 -std=c++23 %s -triple x86_64-linux-gnu -emit-llvm -o - -fexceptions -fcxx-exceptions -pedantic-errors | FileCheck %s --check-prefixes CHECK
+// RUN: %clang_cc1 -std=c++2c %s -triple x86_64-linux-gnu -emit-llvm -o - -fexceptions -fcxx-exceptions -pedantic-errors | FileCheck %s --check-prefixes CHECK
+
+#if __cplusplus == 199711L
+#define static_assert(expr) __extension__ _Static_assert(expr)
+#define noexcept throw()
+#endif
+
+namespace cwg6 { // cwg6: 2.7
+#if __cplusplus >= 201103L
+struct Counter {
+ int copies;
+ constexpr Counter(int copies) : copies(copies) {}
+ constexpr Counter(const Counter& other) : copies(other.copies + 1) {}
+};
+
+// Passing an lvalue by value makes a non-elidable copy.
+constexpr int PassByValue(Counter c) { return c.copies; }
+constexpr int PassByValue2(Counter c) { return PassByValue(c); }
+constexpr int PassByValue3(Counter c) { return PassByValue2(c); }
+static_assert(PassByValue(Counter(0)) == 0, "expect no copies");
+static_assert(PassByValue2(Counter(0)) == 1, "expect 1 copy");
+static_assert(PassByValue3(Counter(0)) == 2, "expect 2 copies");
+#endif
+
+struct A {
+ A() noexcept;
+ A(const A&) noexcept;
+ ~A() noexcept;
+};
+
+inline void f(A a) noexcept {}
+
+// CHECK-LABEL: define {{.*}} @_ZN4cwg64callEv
+void call() {
+ A a;
+ // We copy the parameter here, even though object is not mutated by f and
+ // otherwise satisfies the criteria for the proposed CWG6 optimization.
+ // CHECK: call {{.*}} @_ZN4cwg61AC1ERKS0_(
+ // CHECK: call {{.*}} @_ZN4cwg61fENS_1AE(
+ f(a);
+ // CHECK: call {{.*}} @_ZN4cwg61AD1Ev(
+ // CHECK: call {{.*}} @_ZN4cwg61AD1Ev(
+}
+
+} // namespace cwg6
diff --git a/clang/www/cxx_dr_status.html b/clang/www/cxx_dr_status.html
index ae9b28ee625cd..0312c9dfc0665 100755
--- a/clang/www/cxx_dr_status.html
+++ b/clang/www/cxx_dr_status.html
@@ -81,7 +81,7 @@ <h2 id="cxxdr">C++ defect report implementation status</h2>
<td><a href="https://cplusplus.github.io/CWG/issues/6.html">6</a></td>
<td>NAD</td>
<td>Should the optimization that allows a class object to alias another object also allow the case of a parameter in an inline function to alias its argument?</td>
- <td class="unknown" align="center">Unknown</td>
+ <td class="full" align="center">Yes</td>
</tr>
<tr id="7">
<td><a href="https://cplusplus.github.io/CWG/issues/7.html">7</a></td>
@@ -1318,7 +1318,7 @@ <h2 id="cxxdr">C++ defect report implementation status</h2>
<td><a href="https://cplusplus.github.io/CWG/issues/212.html">212</a></td>
<td>CD4</td>
<td>Implicit instantiation is not described clearly enough</td>
- <td class="unknown" align="center">Unknown</td>
+ <td class="full" align="center">Yes</td>
</tr>
<tr id="213">
<td><a href="https://cplusplus.github.io/CWG/issues/213.html">213</a></td>
@@ -1438,7 +1438,7 @@ <h2 id="cxxdr">C++ defect report implementation status</h2>
<td><a href="https://cplusplus.github.io/CWG/issues/232.html">232</a></td>
<td>NAD</td>
<td>Is indirection through a null pointer undefined behavior?</td>
- <td class="unknown" align="center">Unknown</td>
+ <td class="none" align="center">Duplicate of <a href="#2823">2823</a></td>
</tr>
<tr id="233">
<td><a href="https://cplusplus.github.io/CWG/issues/233.html">233</a></td>
@@ -16790,7 +16790,7 @@ <h2 id="cxxdr">C++ defect report implementation status</h2>
<td><a href="https://cplusplus.github.io/CWG/issues/2823.html">2823</a></td>
<td>CD7</td>
<td>Implicit undefined behavior when dereferencing pointers</td>
- <td class="unknown" align="center">Unknown</td>
+ <td class="none" align="center">No</td>
</tr>
<tr id="2824">
<td><a href="https://cplusplus.github.io/CWG/issues/2824.html">2824</a></td>
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