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 18 10:11:51 PDT 2014
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?
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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