On 20 Jul 2016 1:25 p.m., "Matthias Gehre" <m.ge...@gmx.de> wrote:
>
> mgehre created this revision.
> mgehre added reviewers: klimek, aaron.ballman, rsmith.
> mgehre added a subscriber: cfe-commits.
>
> Look through expressions to determine if a nontype template argument has
been given the value of the template parameter.
>
> https://reviews.llvm.org/D22587
>
> Files:
> lib/AST/ASTContext.cpp
> test/CXX/drs/dr2xx.cpp
>
> Index: test/CXX/drs/dr2xx.cpp
> ===================================================================
> --- test/CXX/drs/dr2xx.cpp
> +++ test/CXX/drs/dr2xx.cpp
> @@ -275,9 +275,9 @@
> static const int my_I = I;
> static const int my_I2 = I+0;
> static const int my_I3 = my_I;
> - B<my_T1, T2, my_I>::type b3; // FIXME: expected-error {{missing
'typename'}}
> + B<my_T1, T2, my_I>::type b3;
> B<my_T1, T2, my_I2>::type b4; // expected-error {{missing
'typename'}}
> - B<my_T1, T2, my_I3>::type b5; // FIXME: expected-error {{missing
'typename'}}
> + B<my_T1, T2, my_I3>::type b5;
> };
> }
>
> Index: lib/AST/ASTContext.cpp
> ===================================================================
> --- lib/AST/ASTContext.cpp
> +++ lib/AST/ASTContext.cpp
> @@ -4448,8 +4448,26 @@
> case TemplateArgument::Null:
> return Arg;
>
> - case TemplateArgument::Expression:
> + case TemplateArgument::Expression: {
> + // Look through variable declarations that have been initialized
to a non-type template
> + // parameter, see 14.6.2.1 [temp.dep.type]:
> + // [...], the argument must have been given the value of
> + // the template parameter and not an expression involving the
template parameter.
> + auto *E = Arg.getAsExpr()->IgnoreImpCasts();
Are all implicit casts really OK here? If the parameter is narrowed, the
value could change. Perhaps we should only walk through lvalue-to-rvalue
conversions here. What about parentheses, should we skip those?
> + while(auto *DeclRef = dyn_cast_or_null<DeclRefExpr>(E)) {
> + auto *D = DeclRef->getDecl();
> + if (isa<NonTypeTemplateParmDecl>(D))
> + return TemplateArgument(DeclRef);
> +
> + auto *VD = dyn_cast<VarDecl>(D);
> + if (!VD)
> + break;
> + E = VD->getInit();
> + if (E)
> + E = E->IgnoreImpCasts();
> + }
> return Arg;
> + }
>
> case TemplateArgument::Declaration: {
> ValueDecl *D =
cast<ValueDecl>(Arg.getAsDecl()->getCanonicalDecl());
>
>
_______________________________________________
cfe-commits mailing list
cfe-commits@lists.llvm.org
http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
