f5b6d0d1d2
In the example of the patch below, during the instantiation of is_convertible at #1, we see at some point Tuple<>. (Let's note '{}' an empty argument pack.) In that context, during the partial specialization the member template template<class... U> Tuple<>::Tuple<U, typename enable_if<and_<is_convertible<U, {}>... >::value, int >::type > Let's look at what happens to the expansion "is_convertible<U, {}>...." To express the result of that expansion tsubst_pack_expansion receives the expansion is_convertible<U, T>, with the argument list [{}]. This function should detect that we have an empty argument pack for the parameter pack T and no argument pack for the parameter pack U. It should thus return a pack expansion "is_convertible<U,T>..." that has this information: "I have gotten an argument list, that is not complete because U doesn't have any argument pack; the argument pack for T is '{}', so I'll wait for the next time I am passed to tsubst_pack_expansion with enough additional argument packs, to really perform the substitution". That information is conveyed by attaching the the '{}' to the PACK_EXPANSION_EXTRA property of the pack expansion returned by tsubst_pack_expansion. The problem in this report is that we are not setting PACK_EXPANSION_EXTRA when the non-complete argument pack list is made of an empty argument pack, because use_pack_expansion_extra_args_p doesn't detect this case. Fixed thus. gcc/cp/ * pt.c (use_pack_expansion_extra_args_p): When at least a parameter pack has an empty argument pack, and another parameter pack has no argument pack at all, use the PACK_EXPANSION_EXTRA mechanism. From-SVN: r198956 |
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| boehm-gc | ||
| config | ||
| contrib | ||
| fixincludes | ||
| gcc | ||
| gnattools | ||
| include | ||
| INSTALL | ||
| intl | ||
| libada | ||
| libatomic | ||
| libbacktrace | ||
| libcpp | ||
| libdecnumber | ||
| libffi | ||
| libgcc | ||
| libgfortran | ||
| libgo | ||
| libgomp | ||
| libiberty | ||
| libitm | ||
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| libmudflap | ||
| libobjc | ||
| libquadmath | ||
| libsanitizer | ||
| libssp | ||
| libstdc++-v3 | ||
| lto-plugin | ||
| maintainer-scripts | ||
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| COPYING.LIB | ||
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| depcomp | ||
| install-sh | ||
| libtool-ldflags | ||
| libtool.m4 | ||
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| ltversion.m4 | ||
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