Bug 53651

Summary: [4.7/4.8 Regression] [C++11] seg fault when specifying using decltype(...)::method
Product: gcc Reporter: Daniel Larimer <dlarimer>
Component: c++Assignee: Jason Merrill <jason>
Status: RESOLVED FIXED    
Severity: normal CC: jason, jason
Priority: P3 Keywords: ice-on-invalid-code
Version: 4.7.0   
Target Milestone: 4.7.2   
Host: Target:
Build: Known to work: 4.6.3
Known to fail: 4.7.0, 4.8.0 Last reconfirmed: 2012-06-13 00:00:00
Attachments: Source file that generated the error.

Description Daniel Larimer 2012-06-13 01:17:25 UTC 
Created attachment 27613 [details]
Source file that generated the error.

Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/opt/local/libexec/gcc/x86_64-apple-darwin11/4.7.0/lto-wrapper
Target: x86_64-apple-darwin11
Configured with: ../gcc-4.7.0/configure --prefix=/opt/local --build=x86_64-apple-darwin11 --enable-languages=c,c++,objc,obj-c++,lto,fortran,java --libdir=/opt/local/lib/gcc47 --includedir=/opt/local/include/gcc47 --infodir=/opt/local/share/info --mandir=/opt/local/share/man --datarootdir=/opt/local/share/gcc-4.7 --with-libiconv-prefix=/opt/local --with-local-prefix=/opt/local --with-system-zlib --disable-nls --program-suffix=-mp-4.7 --with-gxx-include-dir=/opt/local/include/gcc47/c++/ --with-gmp=/opt/local --with-mpfr=/opt/local --with-mpc=/opt/local --with-ppl=/opt/local --with-cloog=/opt/local --enable-cloog-backend=isl --enable-stage1-checking --disable-multilib --enable-lto --with-as=/opt/local/bin/as --with-ld=/opt/local/bin/ld --with-ar=/opt/local/bin/ar --with-bugurl=https://trac.macports.org/newticket --with-pkgversion='MacPorts gcc47 4.7.0_3'
Thread model: posix
gcc version 4.7.0 (MacPorts gcc47 4.7.0_3) 
COLLECT_GCC_OPTIONS='-mmacosx-version-min=10.7.4' '-v' '-save-temps' '-o' 'v5' '-std=c++11' '-shared-libgcc' '-mtune=core2'
 /opt/local/libexec/gcc/x86_64-apple-darwin11/4.7.0/cc1plus -E -quiet -v -D__DYNAMIC__ value5.cpp -fPIC -mmacosx-version-min=10.7.4 -mtune=core2 -std=c++11 -fpch-preprocess -o value5.ii
ignoring nonexistent directory "/opt/local/lib/gcc47/gcc/x86_64-apple-darwin11/4.7.0/../../../../../x86_64-apple-darwin11/include"
#include "..." search starts here:
#include <...> search starts here:
 /opt/local/include/gcc47/c++/
 /opt/local/include/gcc47/c++//x86_64-apple-darwin11
 /opt/local/include/gcc47/c++//backward
 /opt/local/lib/gcc47/gcc/x86_64-apple-darwin11/4.7.0/include
 /opt/local/include
 /opt/local/lib/gcc47/gcc/x86_64-apple-darwin11/4.7.0/include-fixed
 /usr/include
 /System/Library/Frameworks
 /Library/Frameworks
End of search list.
COLLECT_GCC_OPTIONS='-mmacosx-version-min=10.7.4' '-v' '-save-temps' '-o' 'v5' '-std=c++11' '-shared-libgcc' '-mtune=core2'
 /opt/local/libexec/gcc/x86_64-apple-darwin11/4.7.0/cc1plus -fpreprocessed value5.ii -fPIC -quiet -dumpbase value5.cpp -mmacosx-version-min=10.7.4 -mtune=core2 -auxbase value5 -std=c++11 -version -o value5.s
GNU C++ (MacPorts gcc47 4.7.0_3) version 4.7.0 (x86_64-apple-darwin11)
	compiled by GNU C version 4.7.0, GMP version 5.0.4, MPFR version 3.1.0-p3, MPC version 0.9
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
GNU C++ (MacPorts gcc47 4.7.0_3) version 4.7.0 (x86_64-apple-darwin11)
	compiled by GNU C version 4.7.0, GMP version 5.0.4, MPFR version 3.1.0-p3, MPC version 0.9
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: e694c643a962d7980e49500e9a4c6aa5
value5.cpp:38:76: internal compiler error: Segmentation fault: 11
Please submit a full bug report,
with preprocessed source if appropriate.
See <https://trac.macports.org/newticket> for instructions
Comment 1 Jonathan Wakely 2012-06-13 10:01:11 UTC 
The code is has about a dozen errors, the one that causes the ICE is that the decltype-specifier is a reference not a class, and you can't derive from a reference.

Reduced:

template<typename> struct wrap { void bar(); };

template<typename T> auto foo(T* t) -> wrap<T>* { return 0; }

template<typename T>
struct holder : decltype(*foo((T*)0))
{
    using decltype(*foo((T*)0))::bar;
};

holder<int> h;


This is a regression because 4.6.3 doesn't ICE, although the diagnostic isn't very helpful in telling you the decltype-specifier is a reference type:

s2.cc:8:11: error: expected nested-name-specifier before ‘decltype’
s2.cc:8:11: error: expected unqualified-id before ‘decltype’
s2.cc:8:11: error: expected ‘;’ before ‘decltype’
s2.cc:8:34: error: invalid use of ‘::’
Comment 2 H.J. Lu 2012-06-13 14:30:45 UTC 
It is caused by revision 176513:

http://gcc.gnu.org/ml/gcc-cvs/2011-07/msg00780.html
Comment 3 Jason Merrill 2012-06-20 01:18:03 UTC 
Author: jason
Date: Wed Jun 20 01:17:59 2012
New Revision: 188807

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=188807
Log:
	PR c++/53651
	* name-lookup.c (constructor_name_p): Don't try to look at the
	name of a DECLTYPE_TYPE.

Added:
    trunk/gcc/testsuite/g++.dg/cpp0x/decltype37.C
Modified:
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/name-lookup.c
    trunk/gcc/testsuite/ChangeLog
Comment 4 Jason Merrill 2012-06-20 07:22:39 UTC 
Author: jason
Date: Wed Jun 20 07:22:34 2012
New Revision: 188813

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=188813
Log:
	PR c++/53651
	* name-lookup.c (constructor_name_p): Don't try to look at the
	name of a DECLTYPE_TYPE.

Added:
    branches/gcc-4_7-branch/gcc/testsuite/g++.dg/cpp0x/decltype37.C
Modified:
    branches/gcc-4_7-branch/gcc/cp/ChangeLog
    branches/gcc-4_7-branch/gcc/cp/name-lookup.c
    branches/gcc-4_7-branch/gcc/testsuite/ChangeLog
Comment 5 Jason Merrill 2012-06-22 00:35:48 UTC 
Fixed for 4.7.2.