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Patrick Palka a3a4f6be0c c++: Recursive unification with packs and explicit targs [PR94628]
This PR seems to be similar to PR c++/43382, except that the recursive call to
the variadic function with trailing return type in this testcase is additionally
given some explicit template arguments.

In the first testcase below, when resolving the recursive call to 'select',
fn_type_unification first substitutes in the call's explicit template arguments
before doing unification, and so during this substitution the template argument
pack for Args is incomplete.

Since the pack is incomplete, the substitution of 'args...' in the trailing
return type decltype(f(args...)) is handled by the unsubstituted_packs case of
tsubst_pack_expansion.  But the handling of this case happens _before_ we reset
local_specializations, and so the substitution ends up reusing the old binding
for 'args' from local_specializations rather than building a new one.

This patch fixes this issue by setting up local_specializations sooner in
tsubst_pack_expansion, before the handling of the unsubstituted_packs case.
It also adds a new policy to local_specialization_stack so that we could use the
class here to conditionally replace local_specializations.

gcc/cp/ChangeLog:

	PR c++/94628
	* cp-tree.h (lss_policy::lss_nop): New enumerator.
	* pt.c (local_specialization_stack::local_specialization_stack): Handle
	an lss_nop policy.
	(local_specialization_stack::~local_specialization_stack): Likewise.
	(tsubst_pack_expansion): Use a local_specialization_stack instead of
	manually saving and restoring local_specializations.  Conditionally
	replace local_specializations sooner, before the handling of the
	unsubstituted_packs case.

gcc/testsuite/ChangeLog:

	PR c++/94628
	* g++.dg/cpp0x/variadic179.C: New test.
	* g++.dg/cpp0x/variadic180.C: New test.
2020-04-20 18:34:00 -04:00
config Use a non-empty test program to test ability to link. 2020-02-12 13:22:07 -08:00
contrib Do not modify tab options in vimrc for .py files. 2020-04-17 08:55:55 +02:00
fixincludes Allow CONFIG_SHELL to override build-time shell in mkheaders 2020-02-20 22:09:03 -03:00
gcc c++: Recursive unification with packs and explicit targs [PR94628] 2020-04-20 18:34:00 -04:00
gnattools PR81878: fix --disable-bootstrap --enable-languages=ada 2018-11-20 00:07:47 +00:00
gotools libgo: update to Go1.14beta1 2020-01-21 23:53:22 -08:00
include Do not use HAVE_DOS_BASED_FILE_SYSTEM for Cygwin. 2020-04-17 09:22:51 +02:00
INSTALL
intl intl: Unbreak intl build with bison 3 when no regeneration is needed [PR92008] 2020-04-16 11:55:00 +02:00
libada Add `--with-toolexeclibdir=' configuration option 2020-01-24 11:24:25 +00:00
libatomic i386: Remove unneeded assignments when triggering SSE exceptions 2020-04-19 14:27:12 +02:00
libbacktrace libbacktrace: update to current libgo test file 2020-02-15 18:25:13 -08:00
libcc1 c++: Fix return type deduction with an abbreviated function template 2020-02-10 20:43:53 -05:00
libcpp Update cpplib eo.po. 2020-04-06 21:34:20 +00:00
libdecnumber Update copyright years. 2020-01-01 12:51:42 +01:00
libffi Add `--with-toolexeclibdir=' configuration option 2020-01-24 11:24:25 +00:00
libgcc i386: Remove unneeded assignments when triggering SSE exceptions 2020-04-19 14:27:12 +02:00
libgfortran i386: Remove unneeded assignments when triggering SSE exceptions 2020-04-19 14:27:12 +02:00
libgo runtime: use 64 bits of hash seed on arm64 2020-04-15 14:24:33 -07:00
libgomp Add 'dg-do run' to 'libgomp.fortran/target-enter-data-2.F90' 2020-04-20 23:16:40 +02:00
libhsail-rt Add `--with-toolexeclibdir=' configuration option 2020-01-24 11:24:25 +00:00
libiberty Keep .GCC.command.line sections of LTO objetcs 2020-03-05 08:44:11 +01:00
libitm Use a non-empty test program to test ability to link. 2020-02-12 13:22:07 -08:00
libobjc Use a non-empty test program to test ability to link. 2020-02-12 13:22:07 -08:00
liboffloadmic Add `--with-toolexeclibdir=' configuration option 2020-01-24 11:24:25 +00:00
libphobos libphobos: Fix option name for --with-libphobos-druntime-only. 2020-04-20 18:51:10 +02:00
libquadmath Use a non-empty test program to test ability to link. 2020-02-12 13:22:07 -08:00
libsanitizer Darwin, libsanitizer: Adjust minimum supported Darwin version (PR93731). 2020-03-01 14:40:57 +00:00
libssp Use a non-empty test program to test ability to link. 2020-02-12 13:22:07 -08:00
libstdc++-v3 libstdc++: Add test for using istreambuf_iterator with sentinel 2020-04-20 22:06:32 +01:00
libvtv Add `--with-toolexeclibdir=' configuration option 2020-01-24 11:24:25 +00:00
lto-plugin API extension for binutils (type of symbols). 2020-03-19 16:56:27 +01:00
maintainer-scripts maintainer-scripts: Fix up gcc_release without -l, where mkdir was using umask 077 after migration 2020-03-12 18:30:16 +01:00
zlib Add `--with-toolexeclibdir=' configuration option 2020-01-24 11:24:25 +00:00
.dir-locals.el
.gitattributes Add *.md diff=md. 2020-01-15 14:29:53 +01:00
.gitignore Add .clangd and compile_commands.json to .gitignore. 2019-08-28 19:33:28 +00:00
ABOUT-NLS
ar-lib
ChangeLog Do not use HAVE_DOS_BASED_FILE_SYSTEM for Cygwin. 2020-04-17 09:22:51 +02:00
ChangeLog.jit
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config-ml.in MSP430: Add -fno-exceptions multilib 2019-12-11 19:19:50 +00:00
config.guess Update config.sub and config.guess. 2019-09-09 11:14:32 +02:00
config.rpath
config.sub Update config.sub and config.guess. 2019-09-09 11:14:32 +02:00
configure Merge top-level configury changes from gdb 2020-04-09 06:52:55 -06:00
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libtool.m4 [ARM/FDPIC v6 02/24] [ARM] FDPIC: Handle arm*-*-uclinuxfdpiceabi in configure scripts 2019-09-10 09:37:00 +02:00
ltgcc.m4
ltmain.sh Do not use HAVE_DOS_BASED_FILE_SYSTEM for Cygwin. 2020-04-17 09:22:51 +02:00
ltoptions.m4
ltsugar.m4
ltversion.m4
lt~obsolete.m4
MAINTAINERS Add myself as callgraph (IPA) reviewer 2020-04-14 14:12:18 +02:00
Makefile.def Merge top-level configury changes from gdb 2020-04-09 06:52:55 -06:00
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Makefile.tpl Makefile.tpl (HOST_EXPORTS): Add CXX_FOR_BUILD. 2019-08-23 15:37:22 -06:00
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