r216619 - Allow adding dll attributes on certain redecls with a warning if the decl hasn't been used yet (PR20746)
Hans Wennborg
hans at chromium.org
Thu Sep 25 10:27:37 PDT 2014
On Fri, Sep 19, 2014 at 7:06 AM, Tom Stellard <tom at stellard.net> wrote:
> On Thu, Sep 18, 2014 at 10:11:51AM -0700, Hans Wennborg wrote:
>> On Thu, Sep 4, 2014 at 10:36 AM, Hans Wennborg <hans at chromium.org> wrote:
>> > On Thu, Sep 4, 2014 at 10:33 AM, Reid Kleckner <rnk at google.com> wrote:
>> >> Can we merge this to 3.5, or are we done merging patches?
>> >
>> > 3.5-final was tagged a few days ago. I'd be fine with merging this for
>> > 3.5.1, though.
>>
>> Tom, may I merge this to the branch?
>>
>
> Yes, as long as Richard approves.
Richard: Ping?
>> This was discussed on the bug too:
>> http://llvm.org/bugs/show_bug.cgi?id=20746#c12
>>
>> Thanks,
>> Hans
>>
>>
>> >> On Wed, Aug 27, 2014 at 2:27 PM, Hans Wennborg <hans at hanshq.net> wrote:
>> >>>
>> >>> Author: hans
>> >>> Date: Wed Aug 27 16:27:40 2014
>> >>> New Revision: 216619
>> >>>
>> >>> URL: http://llvm.org/viewvc/llvm-project?rev=216619&view=rev
>> >>> Log:
>> >>> Allow adding dll attributes on certain redecls with a warning if the decl
>> >>> hasn't been used yet (PR20746)
>> >>>
>> >>> This shouldn't really be allowed, but it comes up in real code (see PR).
>> >>> As
>> >>> long as the decl hasn't been used there's no technical difficulty in
>> >>> supporting
>> >>> it, so downgrade the error to a warning.
>> >>>
>> >>> Differential Revision: http://reviews.llvm.org/D5087
>> >>>
>> >>> Modified:
>> >>> cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
>> >>> cfe/trunk/lib/Sema/SemaDecl.cpp
>> >>> cfe/trunk/test/Sema/dllexport.c
>> >>> cfe/trunk/test/Sema/dllimport.c
>> >>> cfe/trunk/test/SemaCXX/dllexport.cpp
>> >>> cfe/trunk/test/SemaCXX/dllimport.cpp
>> >>>
>> >>> Modified: cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
>> >>> URL:
>> >>> http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td?rev=216619&r1=216618&r2=216619&view=diff
>> >>>
>> >>> ==============================================================================
>> >>> --- cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td (original)
>> >>> +++ cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td Wed Aug 27
>> >>> 16:27:40 2014
>> >>> @@ -2133,6 +2133,9 @@ def warn_attribute_invalid_on_definition
>> >>> InGroup<IgnoredAttributes>;
>> >>> def err_attribute_dll_redeclaration : Error<
>> >>> "redeclaration of %q0 cannot add %q1 attribute">;
>> >>> +def warn_attribute_dll_redeclaration : Warning<
>> >>> + "redeclaration of %q0 should not add %q1 attribute">,
>> >>> + InGroup<DiagGroup<"dll-attribute-on-redeclaration">>;
>> >>> def err_attribute_dllimport_function_definition : Error<
>> >>> "dllimport cannot be applied to non-inline function definition">;
>> >>> def err_attribute_dll_deleted : Error<
>> >>>
>> >>> Modified: cfe/trunk/lib/Sema/SemaDecl.cpp
>> >>> URL:
>> >>> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaDecl.cpp?rev=216619&r1=216618&r2=216619&view=diff
>> >>>
>> >>> ==============================================================================
>> >>> --- cfe/trunk/lib/Sema/SemaDecl.cpp (original)
>> >>> +++ cfe/trunk/lib/Sema/SemaDecl.cpp Wed Aug 27 16:27:40 2014
>> >>> @@ -5075,7 +5075,7 @@ static void checkDLLAttributeRedeclarati
>> >>> NewDecl = NewTD->getTemplatedDecl();
>> >>>
>> >>> if (!OldDecl || !NewDecl)
>> >>> - return;
>> >>> + return;
>> >>>
>> >>> const DLLImportAttr *OldImportAttr = OldDecl->getAttr<DLLImportAttr>();
>> >>> const DLLExportAttr *OldExportAttr = OldDecl->getAttr<DLLExportAttr>();
>> >>> @@ -5092,13 +5092,30 @@ static void checkDLLAttributeRedeclarati
>> >>> // Implicitly generated declarations are also excluded for now because
>> >>> there
>> >>> // is no other way to switch these to use dllimport or dllexport.
>> >>> bool AddsAttr = !(OldImportAttr || OldExportAttr) && HasNewAttr;
>> >>> +
>> >>> if (AddsAttr && !IsSpecialization && !OldDecl->isImplicit()) {
>> >>> - S.Diag(NewDecl->getLocation(), diag::err_attribute_dll_redeclaration)
>> >>> - << NewDecl
>> >>> - << (NewImportAttr ? (const Attr *)NewImportAttr : NewExportAttr);
>> >>> + // If the declaration hasn't been used yet, allow with a warning for
>> >>> + // free functions and global variables.
>> >>> + bool JustWarn = false;
>> >>> + if (!OldDecl->isUsed() && OldDecl->getDeclContext()->isFileContext())
>> >>> {
>> >>> + auto *VD = dyn_cast<VarDecl>(OldDecl);
>> >>> + if (VD && !VD->getDescribedVarTemplate())
>> >>> + JustWarn = true;
>> >>> + auto *FD = dyn_cast<FunctionDecl>(OldDecl);
>> >>> + if (FD && FD->getTemplatedKind() == FunctionDecl::TK_NonTemplate)
>> >>> + JustWarn = true;
>> >>> + }
>> >>> +
>> >>> + unsigned DiagID = JustWarn ? diag::warn_attribute_dll_redeclaration
>> >>> + : diag::err_attribute_dll_redeclaration;
>> >>> + S.Diag(NewDecl->getLocation(), DiagID)
>> >>> + << NewDecl
>> >>> + << (NewImportAttr ? (const Attr *)NewImportAttr : NewExportAttr);
>> >>> S.Diag(OldDecl->getLocation(), diag::note_previous_declaration);
>> >>> - NewDecl->setInvalidDecl();
>> >>> - return;
>> >>> + if (!JustWarn) {
>> >>> + NewDecl->setInvalidDecl();
>> >>> + return;
>> >>> + }
>> >>> }
>> >>>
>> >>> // A redeclaration is not allowed to drop a dllimport attribute, the
>> >>> only
>> >>>
>> >>> Modified: cfe/trunk/test/Sema/dllexport.c
>> >>> URL:
>> >>> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/dllexport.c?rev=216619&r1=216618&r2=216619&view=diff
>> >>>
>> >>> ==============================================================================
>> >>> --- cfe/trunk/test/Sema/dllexport.c (original)
>> >>> +++ cfe/trunk/test/Sema/dllexport.c Wed Aug 27 16:27:40 2014
>> >>> @@ -39,8 +39,13 @@ __declspec(dllexport) extern int GlobalR
>> >>> int GlobalRedecl2;
>> >>>
>> >>> extern int GlobalRedecl3; //
>> >>> expected-note{{previous declaration is here}}
>> >>> +int useGlobalRedecl3() { return GlobalRedecl3; }
>> >>> __declspec(dllexport) extern int GlobalRedecl3; //
>> >>> expected-error{{redeclaration of 'GlobalRedecl3' cannot add 'dllexport'
>> >>> attribute}}
>> >>>
>> >>> + extern int GlobalRedecl4; //
>> >>> expected-note{{previous declaration is here}}
>> >>> +__declspec(dllexport) extern int GlobalRedecl4; //
>> >>> expected-warning{{redeclaration of 'GlobalRedecl4' should not add
>> >>> 'dllexport' attribute}}
>> >>> +
>> >>> +
>> >>> // External linkage is required.
>> >>> __declspec(dllexport) static int StaticGlobal; //
>> >>> expected-error{{'StaticGlobal' must have external linkage when declared
>> >>> 'dllexport'}}
>> >>>
>> >>> @@ -86,11 +91,18 @@ __declspec(dllexport) void redecl3();
>> >>> void redecl3() {}
>> >>>
>> >>> void redecl4(); // expected-note{{previous
>> >>> declaration is here}}
>> >>> +void useRedecl4() { redecl4(); }
>> >>> __declspec(dllexport) void redecl4(); // expected-error{{redeclaration of
>> >>> 'redecl4' cannot add 'dllexport' attribute}}
>> >>>
>> >>> void redecl5(); // expected-note{{previous
>> >>> declaration is here}}
>> >>> +void useRedecl5() { redecl5(); }
>> >>> __declspec(dllexport) inline void redecl5() {} //
>> >>> expected-error{{redeclaration of 'redecl5' cannot add 'dllexport'
>> >>> attribute}}
>> >>>
>> >>> +// Allow with a warning if the decl hasn't been used yet.
>> >>> + void redecl6(); // expected-note{{previous
>> >>> declaration is here}}
>> >>> +__declspec(dllexport) void redecl6(); // expected-warning{{redeclaration
>> >>> of 'redecl6' should not add 'dllexport' attribute}}
>> >>> +
>> >>> +
>> >>> // External linkage is required.
>> >>> __declspec(dllexport) static int staticFunc(); //
>> >>> expected-error{{'staticFunc' must have external linkage when declared
>> >>> 'dllexport'}}
>> >>>
>> >>>
>> >>> Modified: cfe/trunk/test/Sema/dllimport.c
>> >>> URL:
>> >>> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/dllimport.c?rev=216619&r1=216618&r2=216619&view=diff
>> >>>
>> >>> ==============================================================================
>> >>> --- cfe/trunk/test/Sema/dllimport.c (original)
>> >>> +++ cfe/trunk/test/Sema/dllimport.c Wed Aug 27 16:27:40 2014
>> >>> @@ -64,9 +64,16 @@ int GlobalRedecl2c __attribute__((dllimp
>> >>> __declspec(dllimport) extern int GlobalRedecl3; //
>> >>> expected-note{{previous declaration is here}} expected-note{{previous
>> >>> attribute is here}}
>> >>> extern int GlobalRedecl3; //
>> >>> expected-warning{{'GlobalRedecl3' redeclared without 'dllimport' attribute:
>> >>> previous 'dllimport' ignored}}
>> >>>
>> >>> +// Adding an attribute on redeclaration.
>> >>> extern int GlobalRedecl4; //
>> >>> expected-note{{previous declaration is here}}
>> >>> +int useGlobalRedecl4() { return GlobalRedecl4; }
>> >>> __declspec(dllimport) extern int GlobalRedecl4; //
>> >>> expected-error{{redeclaration of 'GlobalRedecl4' cannot add 'dllimport'
>> >>> attribute}}
>> >>>
>> >>> +// Allow with a warning if the decl hasn't been used yet.
>> >>> + extern int GlobalRedecl5; //
>> >>> expected-note{{previous declaration is here}}
>> >>> +__declspec(dllimport) extern int GlobalRedecl5; //
>> >>> expected-warning{{redeclaration of 'GlobalRedecl5' should not add
>> >>> 'dllimport' attribute}}
>> >>> +
>> >>> +
>> >>> // External linkage is required.
>> >>> __declspec(dllimport) static int StaticGlobal; //
>> >>> expected-error{{'StaticGlobal' must have external linkage when declared
>> >>> 'dllimport'}}
>> >>>
>> >>> @@ -128,14 +135,20 @@ __declspec(dllimport) void redecl3(); //
>> >>> void redecl3() {} // expected-warning{{'redecl3'
>> >>> redeclared without 'dllimport' attribute: previous 'dllimport' ignored}}
>> >>>
>> >>> void redecl4(); // expected-note{{previous
>> >>> declaration is here}}
>> >>> +void useRedecl4() { redecl4(); }
>> >>> __declspec(dllimport) void redecl4(); // expected-error{{redeclaration of
>> >>> 'redecl4' cannot add 'dllimport' attribute}}
>> >>>
>> >>> +// Allow with a warning if the decl hasn't been used yet.
>> >>> + void redecl5(); // expected-note{{previous
>> >>> declaration is here}}
>> >>> +__declspec(dllimport) void redecl5(); // expected-warning{{redeclaration
>> >>> of 'redecl5' should not add 'dllimport' attribute}}
>> >>> +
>> >>> +
>> >>> // Inline redeclarations are fine.
>> >>> -__declspec(dllimport) void redecl5();
>> >>> - inline void redecl5() {}
>> >>> +__declspec(dllimport) void redecl6();
>> >>> + inline void redecl6() {}
>> >>>
>> >>> - void redecl6(); // expected-note{{previous
>> >>> declaration is here}}
>> >>> -__declspec(dllimport) inline void redecl6() {} //
>> >>> expected-error{{redeclaration of 'redecl6' cannot add 'dllimport'
>> >>> attribute}}
>> >>> + void redecl7(); // expected-note{{previous
>> >>> declaration is here}}
>> >>> +__declspec(dllimport) inline void redecl7() {} //
>> >>> expected-warning{{redeclaration of 'redecl7' should not add 'dllimport'
>> >>> attribute}}
>> >>>
>> >>> // External linkage is required.
>> >>> __declspec(dllimport) static int staticFunc(); //
>> >>> expected-error{{'staticFunc' must have external linkage when declared
>> >>> 'dllimport'}}
>> >>>
>> >>> Modified: cfe/trunk/test/SemaCXX/dllexport.cpp
>> >>> URL:
>> >>> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/dllexport.cpp?rev=216619&r1=216618&r2=216619&view=diff
>> >>>
>> >>> ==============================================================================
>> >>> --- cfe/trunk/test/SemaCXX/dllexport.cpp (original)
>> >>> +++ cfe/trunk/test/SemaCXX/dllexport.cpp Wed Aug 27 16:27:40 2014
>> >>> @@ -53,7 +53,7 @@ __declspec(dllexport) extern int GlobalR
>> >>> int GlobalRedecl2;
>> >>>
>> >>> extern int GlobalRedecl3; //
>> >>> expected-note{{previous declaration is here}}
>> >>> -__declspec(dllexport) extern int GlobalRedecl3; //
>> >>> expected-error{{redeclaration of 'GlobalRedecl3' cannot add 'dllexport'
>> >>> attribute}}
>> >>> +__declspec(dllexport) extern int GlobalRedecl3; //
>> >>> expected-warning{{redeclaration of 'GlobalRedecl3' should not add
>> >>> 'dllexport' attribute}}
>> >>>
>> >>> // External linkage is required.
>> >>> __declspec(dllexport) static int StaticGlobal; //
>> >>> expected-error{{'StaticGlobal' must have external linkage when declared
>> >>> 'dllexport'}}
>> >>> @@ -186,10 +186,10 @@ __declspec(dllexport) void redecl2();
>> >>> void redecl2() {}
>> >>>
>> >>> void redecl3(); // expected-note{{previous
>> >>> declaration is here}}
>> >>> -__declspec(dllexport) void redecl3(); // expected-error{{redeclaration of
>> >>> 'redecl3' cannot add 'dllexport' attribute}}
>> >>> +__declspec(dllexport) void redecl3(); // expected-warning{{redeclaration
>> >>> of 'redecl3' should not add 'dllexport' attribute}}
>> >>>
>> >>> void redecl4(); // expected-note{{previous
>> >>> declaration is here}}
>> >>> -__declspec(dllexport) inline void redecl4() {} //
>> >>> expected-error{{redeclaration of 'redecl4' cannot add 'dllexport'
>> >>> attribute}}
>> >>> +__declspec(dllexport) inline void redecl4() {} //
>> >>> expected-warning{{redeclaration of 'redecl4' should not add 'dllexport'
>> >>> attribute}}
>> >>>
>> >>> // Friend functions
>> >>> struct FuncFriend {
>> >>> @@ -200,8 +200,8 @@ struct FuncFriend {
>> >>> };
>> >>> __declspec(dllexport) void friend1() {}
>> >>> void friend2() {}
>> >>> -__declspec(dllexport) void friend3() {} // expected-error{{redeclaration
>> >>> of 'friend3' cannot add 'dllexport' attribute}}
>> >>> -__declspec(dllexport) inline void friend4() {} //
>> >>> expected-error{{redeclaration of 'friend4' cannot add 'dllexport'
>> >>> attribute}}
>> >>> +__declspec(dllexport) void friend3() {} //
>> >>> expected-warning{{redeclaration of 'friend3' should not add 'dllexport'
>> >>> attribute}}
>> >>> +__declspec(dllexport) inline void friend4() {} //
>> >>> expected-warning{{redeclaration of 'friend4' should not add 'dllexport'
>> >>> attribute}}
>> >>>
>> >>> // Implicit declarations can be redeclared with dllexport.
>> >>> __declspec(dllexport) void* operator new(__SIZE_TYPE__ n);
>> >>>
>> >>> Modified: cfe/trunk/test/SemaCXX/dllimport.cpp
>> >>> URL:
>> >>> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/dllimport.cpp?rev=216619&r1=216618&r2=216619&view=diff
>> >>>
>> >>> ==============================================================================
>> >>> --- cfe/trunk/test/SemaCXX/dllimport.cpp (original)
>> >>> +++ cfe/trunk/test/SemaCXX/dllimport.cpp Wed Aug 27 16:27:40 2014
>> >>> @@ -75,7 +75,7 @@ __declspec(dllimport) extern int GlobalR
>> >>> extern int GlobalRedecl3; //
>> >>> expected-warning{{'GlobalRedecl3' redeclared without 'dllimport' attribute:
>> >>> previous 'dllimport' ignored}}
>> >>>
>> >>> extern int GlobalRedecl4; //
>> >>> expected-note{{previous declaration is here}}
>> >>> -__declspec(dllimport) extern int GlobalRedecl4; //
>> >>> expected-error{{redeclaration of 'GlobalRedecl4' cannot add 'dllimport'
>> >>> attribute}}
>> >>> +__declspec(dllimport) extern int GlobalRedecl4; //
>> >>> expected-warning{{redeclaration of 'GlobalRedecl4' should not add
>> >>> 'dllimport' attribute}}
>> >>>
>> >>> // External linkage is required.
>> >>> __declspec(dllimport) static int StaticGlobal; //
>> >>> expected-error{{'StaticGlobal' must have external linkage when declared
>> >>> 'dllimport'}}
>> >>> @@ -224,10 +224,10 @@ __declspec(dllimport) void redecl3(); //
>> >>> void redecl3() {} // expected-warning{{'redecl3'
>> >>> redeclared without 'dllimport' attribute: previous 'dllimport' ignored}}
>> >>>
>> >>> void redecl4(); // expected-note{{previous
>> >>> declaration is here}}
>> >>> -__declspec(dllimport) void redecl4(); // expected-error{{redeclaration of
>> >>> 'redecl4' cannot add 'dllimport' attribute}}
>> >>> +__declspec(dllimport) void redecl4(); // expected-warning{{redeclaration
>> >>> of 'redecl4' should not add 'dllimport' attribute}}
>> >>>
>> >>> void redecl5(); // expected-note{{previous
>> >>> declaration is here}}
>> >>> -__declspec(dllimport) inline void redecl5() {} //
>> >>> expected-error{{redeclaration of 'redecl5' cannot add 'dllimport'
>> >>> attribute}}
>> >>> +__declspec(dllimport) inline void redecl5() {} //
>> >>> expected-warning{{redeclaration of 'redecl5' should not add 'dllimport'
>> >>> attribute}}
>> >>>
>> >>> // Friend functions
>> >>> struct FuncFriend {
>> >>> @@ -240,8 +240,8 @@ struct FuncFriend {
>> >>> __declspec(dllimport) void friend1();
>> >>> void friend2(); // expected-warning{{'friend2'
>> >>> redeclared without 'dllimport' attribute: previous 'dllimport' ignored}}
>> >>> void friend3() {} // expected-warning{{'friend3'
>> >>> redeclared without 'dllimport' attribute: previous 'dllimport' ignored}}
>> >>> -__declspec(dllimport) void friend4(); // expected-error{{redeclaration of
>> >>> 'friend4' cannot add 'dllimport' attribute}}
>> >>> -__declspec(dllimport) inline void friend5() {} //
>> >>> expected-error{{redeclaration of 'friend5' cannot add 'dllimport'
>> >>> attribute}}
>> >>> +__declspec(dllimport) void friend4(); // expected-warning{{redeclaration
>> >>> of 'friend4' should not add 'dllimport' attribute}}
>> >>> +__declspec(dllimport) inline void friend5() {} //
>> >>> expected-warning{{redeclaration of 'friend5' should not add 'dllimport'
>> >>> attribute}}
>> >>>
>> >>> void __declspec(dllimport) friend6(); // expected-note{{previous
>> >>> declaration is here}} expected-note{{previous attribute is here}}
>> >>> void __declspec(dllimport) friend7();
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