[clang] 0af2d43 - [Clang] Warn if both of `dllexport`/`dllimport` and `exclude_from_explicit_instantiation` are specified (#183515)
via cfe-commits
cfe-commits at lists.llvm.org
Wed Mar 4 05:10:28 PST 2026
Author: Tomohiro Kashiwada
Date: 2026-03-04T14:10:23+01:00
New Revision: 0af2d43e06415ce1e8a5d49e864c3881048dd08b
URL: https://github.com/llvm/llvm-project/commit/0af2d43e06415ce1e8a5d49e864c3881048dd08b
DIFF: https://github.com/llvm/llvm-project/commit/0af2d43e06415ce1e8a5d49e864c3881048dd08b.diff
LOG: [Clang] Warn if both of `dllexport`/`dllimport` and `exclude_from_explicit_instantiation` are specified (#183515)
The attributes `exclude_from_explicit_instantiation` and
`dllexport`/`dllimport` serve opposite purposes.
Therefore, if an entity has both attributes, drop one with a warning,
depending on the context of the declaration.
In a template context, the `exclude_from_explicit_instantiation`
attribute takes precedence over the `dllexport` or `dllimport`
attribute. Conversely, the `dllexport` and `dllimport` attributes are
prioritized, in a non-template context.
Added:
clang/test/SemaCXX/attr-exclude_from_explicit_instantiation.ignore-dllattr.cpp
Modified:
clang/include/clang/Basic/DiagnosticSemaKinds.td
clang/lib/Sema/SemaDeclAttr.cpp
Removed:
################################################################################
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index a2d12a3a2c758..8882ac9b8c0a8 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -3790,6 +3790,15 @@ def warn_dllimport_dropped_from_inline_function : Warning<
def warn_nothrow_attribute_ignored : Warning<"'nothrow' attribute conflicts with"
" exception specification; attribute ignored">,
InGroup<IgnoredAttributes>;
+def warn_dllattr_ignored_exclusion_takes_precedence : Warning<
+ "%0 attribute ignored; %1 takes precedence">,
+ InGroup<IgnoredAttributes>;
+def warn_attribute_ignored_on_non_member :
+ Warning<"%0 attribute ignored on a non-member declaration">,
+ InGroup<IgnoredAttributes>;
+def warn_attribute_ignored_in_non_template :
+ Warning<"%0 attribute ignored in a non-template context">,
+ InGroup<IgnoredAttributes>;
def warn_attribute_ignored_on_non_definition :
Warning<"%0 attribute ignored on a non-definition declaration">,
InGroup<IgnoredAttributes>;
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index 3abc69d0e4b96..1b7f41061061d 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -48,6 +48,7 @@
#include "clang/Sema/SemaBPF.h"
#include "clang/Sema/SemaCUDA.h"
#include "clang/Sema/SemaHLSL.h"
+#include "clang/Sema/SemaInternal.h"
#include "clang/Sema/SemaM68k.h"
#include "clang/Sema/SemaMIPS.h"
#include "clang/Sema/SemaMSP430.h"
@@ -705,6 +706,24 @@ static void handleExcludeFromExplicitInstantiationAttr(Sema &S, Decl *D,
<< AL << /*IsMember=*/!isa<CXXRecordDecl>(D);
return;
}
+
+ if (auto *DA = getDLLAttr(D); DA && !DA->isInherited()) {
+ if (auto *RD = dyn_cast<CXXRecordDecl>(D->getDeclContext())) {
+ if (RD->isTemplated()) {
+ S.Diag(DA->getLoc(),
+ diag::warn_dllattr_ignored_exclusion_takes_precedence)
+ << DA << AL;
+ D->dropAttrs<DLLExportAttr, DLLImportAttr>();
+ } else {
+ S.Diag(AL.getLoc(), diag::warn_attribute_ignored_in_non_template) << AL;
+ return;
+ }
+ } else {
+ S.Diag(AL.getLoc(), diag::warn_attribute_ignored_on_non_member) << AL;
+ return;
+ }
+ }
+
D->addAttr(::new (S.Context)
ExcludeFromExplicitInstantiationAttr(S.Context, AL));
}
@@ -6469,6 +6488,22 @@ static void handleDLLAttr(Sema &S, Decl *D, const ParsedAttr &A) {
}
}
+ if (auto *EA = D->getAttr<ExcludeFromExplicitInstantiationAttr>()) {
+ if (auto *RD = dyn_cast<CXXRecordDecl>(D->getDeclContext())) {
+ if (RD->isTemplated()) {
+ S.Diag(A.getRange().getBegin(),
+ diag::warn_dllattr_ignored_exclusion_takes_precedence)
+ << A << EA;
+ return;
+ }
+ S.Diag(EA->getLoc(), diag::warn_attribute_ignored_in_non_template) << EA;
+ D->dropAttr<ExcludeFromExplicitInstantiationAttr>();
+ } else {
+ S.Diag(EA->getLoc(), diag::warn_attribute_ignored_on_non_member) << EA;
+ D->dropAttr<ExcludeFromExplicitInstantiationAttr>();
+ }
+ }
+
Attr *NewAttr = A.getKind() == ParsedAttr::AT_DLLExport
? (Attr *)S.mergeDLLExportAttr(D, A)
: (Attr *)S.mergeDLLImportAttr(D, A);
diff --git a/clang/test/SemaCXX/attr-exclude_from_explicit_instantiation.ignore-dllattr.cpp b/clang/test/SemaCXX/attr-exclude_from_explicit_instantiation.ignore-dllattr.cpp
new file mode 100644
index 0000000000000..5943f99e14cad
--- /dev/null
+++ b/clang/test/SemaCXX/attr-exclude_from_explicit_instantiation.ignore-dllattr.cpp
@@ -0,0 +1,172 @@
+// RUN: %clang_cc1 -triple x86_64-win32 -fms-extensions -fsyntax-only -verify %s
+// RUN: %clang_cc1 -triple x86_64-mingw -fsyntax-only -verify %s
+// RUN: %clang_cc1 -triple x86_64-cygwin -fsyntax-only -verify %s
+
+// Test that attaching the exclude_from_explicit_instantiation attribute and
+// either the dllexport or dllimport attribute together causes a warning.
+// One of them is ignored, depending on the context that is declared.
+
+#define EXCLUDE_ATTR __attribute__((exclude_from_explicit_instantiation))
+
+// Test that exclude_from_explicit_instantiation takes precedence over
+// dllexport/dllimport in a template context.
+template <class T>
+struct class_tmpl_no_instantiated {
+ EXCLUDE_ATTR __declspec(dllexport) void fn_excluded_exported(); // expected-warning{{'dllexport' attribute ignored; 'exclude_from_explicit_instantiation' takes precedence}}
+ EXCLUDE_ATTR __declspec(dllimport) void fn_excluded_imported(); // expected-warning{{'dllimport' attribute ignored; 'exclude_from_explicit_instantiation' takes precedence}}
+ __declspec(dllexport) EXCLUDE_ATTR void fn_exported_excluded(); // expected-warning{{'dllexport' attribute ignored; 'exclude_from_explicit_instantiation' takes precedence}}
+ __declspec(dllimport) EXCLUDE_ATTR void fn_imported_excluded(); // expected-warning{{'dllimport' attribute ignored; 'exclude_from_explicit_instantiation' takes precedence}}
+
+ EXCLUDE_ATTR __declspec(dllexport) static int var_excluded_exported; // expected-warning{{'dllexport' attribute ignored; 'exclude_from_explicit_instantiation' takes precedence}}
+ EXCLUDE_ATTR __declspec(dllimport) static int var_excluded_imported; // expected-warning{{'dllimport' attribute ignored; 'exclude_from_explicit_instantiation' takes precedence}}
+ __declspec(dllexport) EXCLUDE_ATTR static int var_exported_excluded; // expected-warning{{'dllexport' attribute ignored; 'exclude_from_explicit_instantiation' takes precedence}}
+ __declspec(dllimport) EXCLUDE_ATTR static int var_imported_excluded; // expected-warning{{'dllimport' attribute ignored; 'exclude_from_explicit_instantiation' takes precedence}}
+
+ struct EXCLUDE_ATTR __declspec(dllexport) nested_excluded_exported {}; // expected-warning{{'dllexport' attribute ignored; 'exclude_from_explicit_instantiation' takes precedence}}
+ struct EXCLUDE_ATTR __declspec(dllimport) nested_excluded_imported {}; // expected-warning{{'dllimport' attribute ignored; 'exclude_from_explicit_instantiation' takes precedence}}
+ struct __declspec(dllexport) EXCLUDE_ATTR nested_exported_excluded {}; // expected-warning{{'dllexport' attribute ignored; 'exclude_from_explicit_instantiation' takes precedence}}
+ struct __declspec(dllimport) EXCLUDE_ATTR nested_imported_excluded {}; // expected-warning{{'dllimport' attribute ignored; 'exclude_from_explicit_instantiation' takes precedence}}
+
+ template <class U>
+ struct EXCLUDE_ATTR __declspec(dllexport) nested_tmpl_excluded_exported {}; // expected-warning{{'dllexport' attribute ignored; 'exclude_from_explicit_instantiation' takes precedence}}
+ template <class U>
+ EXCLUDE_ATTR __declspec(dllexport) static T var_template_excluded; // expected-warning{{'dllexport' attribute ignored; 'exclude_from_explicit_instantiation' takes precedence}}
+ template <class U>
+ EXCLUDE_ATTR __declspec(dllexport) void fn_template_excluded(); // expected-warning{{'dllexport' attribute ignored; 'exclude_from_explicit_instantiation' takes precedence}}
+
+ struct nested {
+ EXCLUDE_ATTR __declspec(dllexport) void fn_excluded_exported(); // expected-warning{{'dllexport' attribute ignored; 'exclude_from_explicit_instantiation' takes precedence}}
+ };
+
+ struct EXCLUDE_ATTR nested_excluded {
+ __declspec(dllexport) void fn_exported();
+ };
+ struct __declspec(dllexport) nested_exported {
+ EXCLUDE_ATTR void fn_excluded();
+ };
+ struct __declspec(dllimport) nested_imported {
+ EXCLUDE_ATTR void fn_excluded();
+ };
+
+ template <class U>
+ struct nested_tmpl {
+ EXCLUDE_ATTR __declspec(dllexport) void fn_excluded_exported(); // expected-warning{{'dllexport' attribute ignored; 'exclude_from_explicit_instantiation' takes precedence}}
+ };
+};
+
+// Test that a class-level dll attribute doesn't cause a warning on an excluded member.
+template <class T>
+struct __declspec(dllexport) class_tmpl_exported {
+ EXCLUDE_ATTR void fn_excluded();
+};
+template struct class_tmpl_exported<int>;
+void use_class_tmpl_exported() { class_tmpl_exported<long>().fn_excluded(); }
+
+template <class T>
+struct __declspec(dllimport) class_tmpl_imported {
+ EXCLUDE_ATTR void fn_excluded();
+};
+template struct class_tmpl_imported<int>;
+void use_class_tmpl_imported() { class_tmpl_imported<long>().fn_excluded(); }
+
+// Test that a dll attribute on an explicit instantiation doesn't cause a warning on
+// an excluded member.
+template <class T>
+struct class_tmpl_explicit_inst {
+ EXCLUDE_ATTR void fn_excluded();
+ EXCLUDE_ATTR static T var_excluded;
+ struct EXCLUDE_ATTR nested_excluded {
+ __declspec(dllexport) void fn_exported();
+ __declspec(dllimport) void fn_imported();
+ };
+
+ struct __declspec(dllexport) nested_exported {
+ EXCLUDE_ATTR void fn_excluded();
+ };
+ struct __declspec(dllimport) nested_imported {
+ EXCLUDE_ATTR void fn_excluded();
+ };
+};
+extern template struct __declspec(dllimport) class_tmpl_explicit_inst<long>;
+template struct __declspec(dllexport) class_tmpl_explicit_inst<int>;
+
+// Test that exclude_from_explicit_instantiation is ignored in a non-template context.
+struct class_nontmpl {
+ EXCLUDE_ATTR __declspec(dllexport) void fn_excluded_exported(); // expected-warning{{'exclude_from_explicit_instantiation' attribute ignored in a non-template context}}
+ EXCLUDE_ATTR __declspec(dllimport) void fn_excluded_imported(); // expected-warning{{'exclude_from_explicit_instantiation' attribute ignored in a non-template context}}
+ __declspec(dllexport) EXCLUDE_ATTR void fn_exported_excluded(); // expected-warning{{'exclude_from_explicit_instantiation' attribute ignored in a non-template context}}
+ __declspec(dllimport) EXCLUDE_ATTR void fn_imported_excluded(); // expected-warning{{'exclude_from_explicit_instantiation' attribute ignored in a non-template context}}
+
+ EXCLUDE_ATTR __declspec(dllexport) static int var_excluded_exported; // expected-warning{{'exclude_from_explicit_instantiation' attribute ignored in a non-template context}}
+ EXCLUDE_ATTR __declspec(dllimport) static int var_excluded_imported; // expected-warning{{'exclude_from_explicit_instantiation' attribute ignored in a non-template context}}
+ __declspec(dllexport) EXCLUDE_ATTR static int var_exported_excluded; // expected-warning{{'exclude_from_explicit_instantiation' attribute ignored in a non-template context}}
+ __declspec(dllimport) EXCLUDE_ATTR static int var_imported_excluded; // expected-warning{{'exclude_from_explicit_instantiation' attribute ignored in a non-template context}}
+
+ struct EXCLUDE_ATTR __declspec(dllexport) nested_excluded_exported {}; // expected-warning{{'exclude_from_explicit_instantiation' attribute ignored in a non-template context}}
+ struct EXCLUDE_ATTR __declspec(dllimport) nested_excluded_imported {}; // expected-warning{{'exclude_from_explicit_instantiation' attribute ignored in a non-template context}}
+ struct __declspec(dllexport) EXCLUDE_ATTR nested_exported_excluded {}; // expected-warning{{'exclude_from_explicit_instantiation' attribute ignored in a non-template context}}
+ struct __declspec(dllimport) EXCLUDE_ATTR nested_imported_excluded {}; // expected-warning{{'exclude_from_explicit_instantiation' attribute ignored in a non-template context}}
+
+ template <class T>
+ struct EXCLUDE_ATTR __declspec(dllexport) class_template_excluded {}; // expected-warning{{'exclude_from_explicit_instantiation' attribute ignored in a non-template context}}
+ template <class T>
+ EXCLUDE_ATTR __declspec(dllexport) static T var_template_excluded; // expected-warning{{'exclude_from_explicit_instantiation' attribute ignored in a non-template context}}
+ template <class T>
+ EXCLUDE_ATTR __declspec(dllexport) void fn_template_excluded(); // expected-warning{{'exclude_from_explicit_instantiation' attribute ignored in a non-template context}}
+
+ struct nested {
+ EXCLUDE_ATTR __declspec(dllexport) void fn_excluded_exported(); // expected-warning{{'exclude_from_explicit_instantiation' attribute ignored in a non-template context}}
+ };
+
+ struct EXCLUDE_ATTR nested_excluded {
+ __declspec(dllexport) void fn_excluded_exported();
+ };
+ struct __declspec(dllexport) nested_exported {
+ EXCLUDE_ATTR void fn_excluded();
+ };
+ struct __declspec(dllimport) nested_imported {
+ EXCLUDE_ATTR void fn_excluded();
+ };
+
+ template <class T>
+ struct nested_tmpl {
+ EXCLUDE_ATTR __declspec(dllexport) void fn_excluded_exported(); // expected-warning{{'dllexport' attribute ignored; 'exclude_from_explicit_instantiation' takes precedence}}
+ };
+};
+
+// Test that exclude_from_explicit_instantiation is ignored on a non-member entity.
+EXCLUDE_ATTR __declspec(dllexport) void fn_excluded_exported(); // expected-warning{{'exclude_from_explicit_instantiation' attribute ignored on a non-member declaration}}
+EXCLUDE_ATTR __declspec(dllimport) void fn_excluded_imported(); // expected-warning{{'exclude_from_explicit_instantiation' attribute ignored on a non-member declaration}}
+__declspec(dllexport) EXCLUDE_ATTR void fn_exported_excluded(); // expected-warning{{'exclude_from_explicit_instantiation' attribute ignored on a non-member declaration}}
+__declspec(dllimport) EXCLUDE_ATTR void fn_imported_excluded(); // expected-warning{{'exclude_from_explicit_instantiation' attribute ignored on a non-member declaration}}
+
+EXCLUDE_ATTR __declspec(dllexport) int var_excluded_exported; // expected-warning{{'exclude_from_explicit_instantiation' attribute ignored on a non-member declaration}}
+EXCLUDE_ATTR __declspec(dllimport) int var_excluded_imported; // expected-warning{{'exclude_from_explicit_instantiation' attribute ignored on a non-member declaration}}
+__declspec(dllexport) EXCLUDE_ATTR int var_exported_excluded; // expected-warning{{'exclude_from_explicit_instantiation' attribute ignored on a non-member declaration}}
+__declspec(dllimport) EXCLUDE_ATTR int var_imported_excluded; // expected-warning{{'exclude_from_explicit_instantiation' attribute ignored on a non-member declaration}}
+
+struct EXCLUDE_ATTR __declspec(dllexport) class_excluded_exported {}; // expected-warning{{'exclude_from_explicit_instantiation' attribute ignored on a non-member declaration}}
+struct EXCLUDE_ATTR __declspec(dllimport) class_excluded_imported {}; // expected-warning{{'exclude_from_explicit_instantiation' attribute ignored on a non-member declaration}}
+struct __declspec(dllexport) EXCLUDE_ATTR class_exported_excluded {}; // expected-warning{{'exclude_from_explicit_instantiation' attribute ignored on a non-member declaration}}
+struct __declspec(dllimport) EXCLUDE_ATTR class_imported_excluded {}; // expected-warning{{'exclude_from_explicit_instantiation' attribute ignored on a non-member declaration}}
+
+template <class T>
+struct EXCLUDE_ATTR __declspec(dllexport) class_tmpl_excluded_exported {}; // expected-warning{{'exclude_from_explicit_instantiation' attribute ignored on a non-member declaration}}
+template <class T>
+EXCLUDE_ATTR __declspec(dllexport) T var_template_excluded; // expected-warning{{'exclude_from_explicit_instantiation' attribute ignored on a non-member declaration}}
+template <class T>
+EXCLUDE_ATTR __declspec(dllexport) void fn_template_excluded(); // expected-warning{{'exclude_from_explicit_instantiation' attribute ignored on a non-member declaration}}
+
+EXCLUDE_ATTR void fn_excluded();
+
+EXCLUDE_ATTR int var_excluded;
+
+struct EXCLUDE_ATTR class_excluded {
+ __declspec(dllexport) void fn_excluded_exported();
+};
+struct __declspec(dllexport) class_exported {
+ EXCLUDE_ATTR void fn_excluded();
+};
+struct __declspec(dllimport) class_imported {
+ EXCLUDE_ATTR void fn_excluded();
+};
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