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[Clang] Implement CWG3005 Function parameters should never be name-independent #138245

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Merged
merged 3 commits into from
May 2, 2025
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[Clang] Implement CWG3005 Function parameters should never be name-independent #138245

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[Clang] Implement CWG3005 Function parameters should never be name-in…
cor3ntin May 2, 2025
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cor3ntin May 2, 2025
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fix test
cor3ntin May 2, 2025
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2 changes: 2 additions & 0 deletions clang/docs/ReleaseNotes.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -134,6 +134,8 @@ Resolutions to C++ Defect Reports
- Bumped the ``__cpp_constexpr`` feature-test macro to ``202002L`` in C++20 mode as indicated in
`P2493R0 <https://wg21.link/P2493R0>`_.

- Implemented `CWG3005 Function parameters should never be name-independent <https://wg21.link/CWG3005>`_.

C Language Changes
------------------

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10 changes: 7 additions & 3 deletions clang/lib/Sema/SemaDecl.cpp
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Expand Up @@ -7542,16 +7542,20 @@ NamedDecl *Sema::ActOnVariableDeclarator(

DeclSpec::SCS SCSpec = D.getDeclSpec().getStorageClassSpec();
StorageClass SC = StorageClassSpecToVarDeclStorageClass(D.getDeclSpec());

if (LangOpts.CPlusPlus && (DC->isClosure() || DC->isFunctionOrMethod()) &&
SC != SC_Static && SC != SC_Extern && II && II->isPlaceholder()) {

IsPlaceholderVariable = true;

if (!Previous.empty()) {
NamedDecl *PrevDecl = *Previous.begin();
bool SameDC = PrevDecl->getDeclContext()->getRedeclContext()->Equals(
DC->getRedeclContext());
if (SameDC && isDeclInScope(PrevDecl, CurContext, S, false))
DiagPlaceholderVariableDefinition(D.getIdentifierLoc());
if (SameDC && isDeclInScope(PrevDecl, CurContext, S, false)) {
IsPlaceholderVariable = !isa<ParmVarDecl>(PrevDecl);
if (IsPlaceholderVariable)
DiagPlaceholderVariableDefinition(D.getIdentifierLoc());
}
}
}

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23 changes: 23 additions & 0 deletions clang/test/CXX/drs/cwg30xx.cpp
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I'm not going to bother you with the description of what I want to see in this file. Here you go:

// RUN: %clang_cc1 -std=c++98 -pedantic-errors -verify=expected %s
// RUN: %clang_cc1 -std=c++11 -pedantic-errors -verify=expected %s
// RUN: %clang_cc1 -std=c++14 -pedantic-errors -verify=expected %s
// RUN: %clang_cc1 -std=c++17 -pedantic-errors -verify=expected %s
// RUN: %clang_cc1 -std=c++20 -pedantic-errors -verify=expected %s
// RUN: %clang_cc1 -std=c++23 -pedantic-errors -verify=expected %s
// RUN: %clang_cc1 -std=c++2c -pedantic-errors -verify=expected %s


namespace cwg3005 { // cwg3005: 21 open 2025-03-10

void f(
  int _, // #cwg3005-first-param
  int _)
  // expected-error@-1 {{redefinition of parameter '_'}}
  //   expected-note@#cwg3005-first-param {{previous declaration is here}}
{
  int _;
  // expected-error@-1 {{redefinition of '_'}}
  //   expected-note@#cwg3005-first-param {{previous declaration is here}}
}

} // namespace cwg3005

Original file line number Diff line number Diff line change
@@ -0,0 +1,23 @@
// RUN: %clang_cc1 -std=c++98 -pedantic-errors -verify=expected %s
// RUN: %clang_cc1 -std=c++11 -pedantic-errors -verify=expected %s
// RUN: %clang_cc1 -std=c++14 -pedantic-errors -verify=expected %s
// RUN: %clang_cc1 -std=c++17 -pedantic-errors -verify=expected %s
// RUN: %clang_cc1 -std=c++20 -pedantic-errors -verify=expected %s
// RUN: %clang_cc1 -std=c++23 -pedantic-errors -verify=expected %s
// RUN: %clang_cc1 -std=c++2c -pedantic-errors -verify=expected %s


namespace cwg3005 { // cwg3005: 21 open 2025-03-10

void f(
int _, // #cwg3005-first-param
int _)
// expected-error@-1 {{redefinition of parameter '_'}}
// expected-note@#cwg3005-first-param {{previous definition is here}}
{
int _;
// expected-error@-1 {{redefinition of '_'}}
// expected-note@#cwg3005-first-param {{previous declaration is here}}
}

} // namespace cwg3005
6 changes: 5 additions & 1 deletion clang/www/cxx_dr_status.html
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Expand Up @@ -17890,7 +17890,11 @@ <h2 id="cxxdr">C++ defect report implementation status</h2>
<td><a href="https://cplusplus.github.io/CWG/issues/3005.html">3005</a></td>
<td>open</td>
<td>Function parameters should never be name-independent</td>
<td align="center">Not resolved</td>
<td align="center">
<details>
<summary>Not resolved</summary>
Clang 21 implements 2025-03-10 resolution
</details></td>
</tr>
<tr class="open" id="3006">
<td><a href="https://cplusplus.github.io/CWG/issues/3006.html">3006</a></td>
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