r210715 - Don't inherit dllimport to inline move assignment operators

[Hans Wennborg]

Yes, but since it's only a CTP I don't think of it as a current version. 
It seems they haven't bumped the msc-ver number yet, so we can't really 
differentiate based on that.

Note that we still _export_ move operators, it's just that we don't rely 
on msvc to do the same. So this is compatible both ways, except that it 
breaks pointer equality of that operator.

  - Hans

On 06/11/2014 05:11 PM, David Majnemer wrote:
> VS "14" does dllimport inline move-assignment operators.
>
>
> On Wed, Jun 11, 2014 at 6:44 PM, Hans Wennborg <hans at hanshq.net
> <mailto:hans at hanshq.net>> wrote:
>
>     Author: hans
>     Date: Wed Jun 11 17:44:39 2014
>     New Revision: 210715
>
>     URL: http://llvm.org/viewvc/llvm-project?rev=210715&view=rev
>     Log:
>     Don't inherit dllimport to inline move assignment operators
>
>     Current MSVC versions don't have move assignment operators, so we
>     can't rely on them being available in the dll. If we have the
>     definition, we can just use that directly. This breaks pointer
>     equality, but should work fine otherwise.
>
>     When there is an MSVC version that supports move assignment,
>     we can key this off the -fmsc-ver option.
>
>     http://reviews.llvm.org/D4105
>
>     Modified:
>          cfe/trunk/lib/Sema/SemaDeclCXX.cpp
>          cfe/trunk/test/CodeGenCXX/dllimport.cpp
>
>     Modified: cfe/trunk/lib/Sema/SemaDeclCXX.cpp
>     URL:
>     http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaDeclCXX.cpp?rev=210715&r1=210714&r2=210715&view=diff
>     ==============================================================================
>     --- cfe/trunk/lib/Sema/SemaDeclCXX.cpp (original)
>     +++ cfe/trunk/lib/Sema/SemaDeclCXX.cpp Wed Jun 11 17:44:39 2014
>     @@ -4377,10 +4377,23 @@ static void checkDLLAttribute(Sema &S, C
>         // specialization bases.
>
>         for (Decl *Member : Class->decls()) {
>     -    if (!isa<CXXMethodDecl>(Member) && !isa<VarDecl>(Member))
>     +    VarDecl *VD = dyn_cast<VarDecl>(Member);
>     +    CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(Member);
>     +
>     +    // Only methods and static fields inherit the attributes.
>     +    if (!VD && !MD)
>     +      continue;
>     +
>     +    // Don't process deleted methods.
>     +    if (MD && MD->isDeleted())
>             continue;
>     -    if (isa<CXXMethodDecl>(Member) &&
>     cast<CXXMethodDecl>(Member)->isDeleted())
>     +
>     +    if (MD && MD->isMoveAssignmentOperator() && !ClassExported &&
>     +        MD->isInlined()) {
>     +      // Current MSVC versions don't export the move assignment
>     operators, so
>     +      // don't attempt to import them if we have a definition.
>             continue;
>     +    }
>
>           if (InheritableAttr *MemberAttr = getDLLAttr(Member)) {
>             if (S.Context.getTargetInfo().getCXXABI().isMicrosoft() &&
>
>     Modified: cfe/trunk/test/CodeGenCXX/dllimport.cpp
>     URL:
>     http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/dllimport.cpp?rev=210715&r1=210714&r2=210715&view=diff
>     ==============================================================================
>     --- cfe/trunk/test/CodeGenCXX/dllimport.cpp (original)
>     +++ cfe/trunk/test/CodeGenCXX/dllimport.cpp Wed Jun 11 17:44:39 2014
>     @@ -27,6 +27,8 @@ struct ExplicitSpec_NotImported {};
>       #define USE(func) void UNIQ(use)() { func(); }
>       #define USEMEMFUNC(class, func) void (class::*UNIQ(use)())() {
>     return &class::func; }
>       #define USECLASS(class) void UNIQ(USE)() { class x; }
>     +#define USECOPYASSIGN(class) class& (class::*UNIQ(use)())(class&) {
>     return &class::operator=; }
>     +#define USEMOVEASSIGN(class) class& (class::*UNIQ(use)())(class&&)
>     { return &class::operator=; }
>
>       //===----------------------------------------------------------------------===//
>       // Globals
>     @@ -518,9 +520,18 @@ struct __declspec(dllimport) T {
>
>         static int b;
>         // MO1-DAG: @"\01?b at T@@2HA" = external dllimport global i32
>     +
>     +  T& operator=(T&) = default;
>     +  // MO1-DAG: define available_externally dllimport x86_thiscallcc
>     nonnull %struct.T* @"\01??4T@@QAEAAU0 at AAU0@@Z"
>     +
>     +  T& operator=(T&&) = default;
>     +  // Note: Don't mark inline move operators dllimport because
>     current MSVC versions don't export them.
>     +  // MO1-DAG: define linkonce_odr x86_thiscallcc nonnull %struct.T*
>     @"\01??4T@@QAEAAU0@$$QAU0@@Z"
>       };
>       USEMEMFUNC(T, a)
>       USEVAR(T::b)
>     +USECOPYASSIGN(T)
>     +USEMOVEASSIGN(T)
>
>       template <typename T> struct __declspec(dllimport) U { void foo()
>     {} };
>       // MO1-DAG: define available_externally dllimport x86_thiscallcc
>     void @"\01?foo@?$U at H@@QAEXXZ"
>
>
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