[clang][Sema] Fix diagnostic for function overloading in extern "C" #106033
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@llvm/pr-subscribers-clang Author: None (s-watanabe314) ChangesFixes #80235 When trying to overload a function within This patch uses Regression tests verify that the expected diagnostics are given when trying to overload functions within Full diff: https://github.com/llvm/llvm-project/pull/106033.diff 2 Files Affected:
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 503e93f9257137..63bd15dad7c48a 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -3882,6 +3882,10 @@ bool Sema::MergeFunctionDecl(FunctionDecl *New, NamedDecl *&OldD, Scope *S,
if (New->isCXXClassMember() && New->isOutOfLine())
Diag(New->getLocation(), diag::err_member_def_does_not_match_ret_type)
<< New << New->getReturnTypeSourceRange();
+ else if (Old->isExternC() && New->isExternC() &&
+ !Old->hasAttr<OverloadableAttr>() &&
+ !New->hasAttr<OverloadableAttr>())
+ Diag(New->getLocation(), diag::err_conflicting_types) << New;
else
Diag(New->getLocation(), diag::err_ovl_diff_return_type)
<< New->getReturnTypeSourceRange();
diff --git a/clang/test/SemaCXX/extern-c.cpp b/clang/test/SemaCXX/extern-c.cpp
index 68d1494b94918f..86012670ddcd57 100644
--- a/clang/test/SemaCXX/extern-c.cpp
+++ b/clang/test/SemaCXX/extern-c.cpp
@@ -77,6 +77,19 @@ namespace foo {
}
}
+namespace extern_ovl {
+ extern "C" {
+ __attribute__((overloadable))
+ void ovl_decl(void); // expected-note {{previous}}
+
+ __attribute__((overloadable))
+ int ovl_decl(int);
+
+ __attribute__((overloadable))
+ int ovl_decl(void); // expected-error {{functions that differ only in their return type}}
+ }
+}
+
namespace linkage {
namespace redecl {
extern "C" {
@@ -88,6 +101,12 @@ namespace linkage {
void linkage_redecl(double); // expected-error {{conflicting types}}
}
}
+ namespace redecl_2 {
+ extern "C" {
+ void linkage_redecl_2(); // expected-note {{previous}}
+ int linkage_redecl_2(int); // expected-error {{conflicting types}}
+ }
+ }
namespace from_outer {
void linkage_from_outer_1(); // expected-note {{previous}}
void linkage_from_outer_2(); // expected-note {{previous}}
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s-watanabe314
changed the title
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Ah, actually, this is still missing a release note (in |
Fixes llvm#80235 When trying to overload a function within `extern "C"`, the diagnostic `functions that differ only in their return type cannot be overloaded` is given. This diagnostic is inappropriate because overloading is basically not allowed in the C language. However, if the redeclared function has the `((overloadable))` attribute, it should be diagnosed as `functions that differ only in their return type cannot be overloaded`. This patch uses `isExternC()` to provide an appropriate diagnostic during the diagnostic process. `isExternC()` updates the linkage information cache internally, so calling it before merging functions can cause clang to crash. An example is declaring `static void foo()` and `void foo()` within an `extern "C"` block. Therefore, I decided to call `isExternC()` after the compilation error is confirmed and select the diagnostic message. The diagnostic message is `conflicting types for 'func'` similar to the diagnostic in C, and `functions that differ only in their return type cannot be overloaded` if the `((overloadable))` attribute is given. Regression tests verify that the expected diagnostics are given when trying to overload functions within `extern "C"` and when the `((overloadable))` attribute is present.
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Thank you for comments. I added release note. |
Co-authored-by: Sirraide <[email protected]>
Seems OK to me |
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Thank you for the approval. I have been granted commit access, so I will merge it myself. |
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/72/builds/2892 Here is the relevant piece of the build log for the reference |
Fixes #80235
When trying to overload a function within
extern "C", the diagnosticfunctions that differ only in their return type cannot be overloadedis given. This diagnostic is inappropriate because overloading is basically not allowed in the C language. However, if the redeclared function has the((overloadable))attribute, it should be diagnosed asfunctions that differ only in their return type cannot be overloaded.This patch uses
isExternC()to provide an appropriate diagnostic during the diagnostic process.isExternC()updates the linkage information cache internally, so calling it before merging functions can cause clang to crash. An example is declaringstatic void foo()andvoid foo()within anextern "C"block. Therefore, I decided to callisExternC()after the compilation error is confirmed and select the diagnostic message. The diagnostic message isconflicting types for 'func'similar to the diagnostic in C, andfunctions that differ only in their return type cannot be overloadedif the((overloadable))attribute is given.Regression tests verify that the expected diagnostics are given when trying to overload functions within
extern "C"and when the((overloadable))attribute is present.