r242973 - Downgrade error about adding 'dllimport' to used free function to warning (PR24215)

[Richard Smith]

Approved.

On Mon, Jul 27, 2015 at 1:20 PM, Hans Wennborg <hans at chromium.org> wrote:

> Ping?
>
> On Thu, Jul 23, 2015 at 4:45 PM, Hans Wennborg <hans at chromium.org> wrote:
> > This isn't fixing a regression, but would be nice to have in 3.7 I think.
> >
> > Richard, is this OK for merging?
> >
> > On Wed, Jul 22, 2015 at 4:54 PM, Hans Wennborg <hans at hanshq.net> wrote:
> >> Author: hans
> >> Date: Wed Jul 22 18:54:51 2015
> >> New Revision: 242973
> >>
> >> URL: http://llvm.org/viewvc/llvm-project?rev=242973&view=rev
> >> Log:
> >> Downgrade error about adding 'dllimport' to used free function to
> warning (PR24215)
> >>
> >> The code will still work as it can reference the function via its thunk.
> >>
> >> Modified:
> >>     cfe/trunk/lib/Sema/SemaDecl.cpp
> >>     cfe/trunk/test/Sema/dllimport.c
> >>
> >> Modified: cfe/trunk/lib/Sema/SemaDecl.cpp
> >> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaDecl.cpp?rev=242973&r1=242972&r2=242973&view=diff
> >>
> ==============================================================================
> >> --- cfe/trunk/lib/Sema/SemaDecl.cpp (original)
> >> +++ cfe/trunk/lib/Sema/SemaDecl.cpp Wed Jul 22 18:54:51 2015
> >> @@ -5368,10 +5368,9 @@ static void checkDLLAttributeRedeclarati
> >>    bool AddsAttr = !(OldImportAttr || OldExportAttr) && HasNewAttr;
> >>
> >>    if (AddsAttr && !IsSpecialization && !OldDecl->isImplicit()) {
> >> -    // If the declaration hasn't been used yet, allow with a warning
> for
> >> -    // free functions and global variables.
> >> +    // Allow with a warning for free functions and global variables.
> >>      bool JustWarn = false;
> >> -    if (!OldDecl->isUsed() && !OldDecl->isCXXClassMember()) {
> >> +    if (!OldDecl->isCXXClassMember()) {
> >>        auto *VD = dyn_cast<VarDecl>(OldDecl);
> >>        if (VD && !VD->getDescribedVarTemplate())
> >>          JustWarn = true;
> >> @@ -5380,6 +5379,13 @@ static void checkDLLAttributeRedeclarati
> >>          JustWarn = true;
> >>      }
> >>
> >> +    // We cannot change a declaration that's been used because IR has
> already
> >> +    // been emitted. Dllimported functions will still work though
> (modulo
> >> +    // address equality) as they can use the thunk.
> >> +    if (OldDecl->isUsed())
> >> +      if (!isa<FunctionDecl>(OldDecl) || !NewImportAttr)
> >> +        JustWarn = false;
> >> +
> >>      unsigned DiagID = JustWarn ? diag::warn_attribute_dll_redeclaration
> >>                                 : diag::err_attribute_dll_redeclaration;
> >>      S.Diag(NewDecl->getLocation(), DiagID)
> >>
> >> Modified: cfe/trunk/test/Sema/dllimport.c
> >> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/dllimport.c?rev=242973&r1=242972&r2=242973&view=diff
> >>
> ==============================================================================
> >> --- cfe/trunk/test/Sema/dllimport.c (original)
> >> +++ cfe/trunk/test/Sema/dllimport.c Wed Jul 22 18:54:51 2015
> >> @@ -143,7 +143,7 @@ __declspec(dllimport) void redecl3(); //
> >>
> >>                        void redecl4(); // expected-note{{previous
> declaration is here}}
> >>  void useRedecl4() { redecl4(); }
> >> -__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}}
> >>
> >>  // Allow with a warning if the decl hasn't been used yet.
> >>                        void redecl5(); // expected-note{{previous
> declaration is here}}
> >>
> >>
> >> _______________________________________________
> >> cfe-commits mailing list
> >> cfe-commits at cs.uiuc.edu
> >> http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits
>
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