r216619 - Allow adding dll attributes on certain redecls with a warning if the decl hasn't been used yet (PR20746)
Tom Stellard
tom at stellard.net
Fri Sep 19 07:06:25 PDT 2014
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.
-Tom
> 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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