gcc6 vs mail/thunderbird: ICE

[Thomas Klausner <tk%giga.or.at@localhost>]

I see an internal compiler error when building mail/thunderbird on
8.99.12/amd64 from this week with
CFLAGS+=-g
CPPFLAGS+=-g
CXXPPFLAGS+=-g
in case it matters:

/scratch/mail/thunderbird/work/.cwrapper/bin/c++ -std=gnu++11 -o Unified_cpp_layout_tables0.o -c -I/scratch/mail/thunderbird/work/build/dist/stl_wrappers -I/scratch/mail/thunderbird/work/build/dist/system_wrappers -include /scratch/mail/thunderbird/work/thunderbird-52.5.2/mozilla/config/gcc_hidden.h -DNDEBUG=1 -DTRIMMED=1 -DDEBUG_TABLE_STRATEGY_off -DSTATIC_EXPORTABLE_JS_API -DMOZ_HAS_MOZGLUE -DMOZILLA_INTERNAL_API -DIMPL_LIBXUL -I/scratch/mail/thunderbird/work/thunderbird-52.5.2/mozilla/layout/tables -I/scratch/mail/thunderbird/work/build/layout/tables -I/scratch/mail/thunderbird/work/thunderbird-52.5.2/mozilla/intl/unicharutil/util -I/scratch/mail/thunderbird/work/thunderbird-52.5.2/mozilla/layout/base -I/scratch/mail/thunderbird/work/thunderbird-52.5.2/mozilla/layout/generic -I/scratch/mail/thunderbird/work/thunderbird-52.5.2/mozilla/layout/style -I/scratch/mail/thunderbird/work/thunderbird-52.5.2/mozilla/layout/xul -I/scratch/mail/thunderbird/work/thunderbird-52.5.2/mozilla/dom/base -I/scratch/mail/thunderbird/work/thunderbird-52.5.2/mozilla/dom/html -I/scratch/mail/thunderbird/work/build/dist/include  -I/usr/pkg/include/nspr -I/usr/pkg/include/nss -I/usr/pkg/include/nspr    -I/usr/pkg/include/pixman-1   -fPIC -DPIC  -DMOZILLA_CLIENT -include /scratch/mail/thunderbird/work/build/mozilla-config.h -MD -MP -MF .deps/Unified_cpp_layout_tables0.o.pp -g -I/usr/include -I/usr/pkg/include -I/usr/pkg/include/nspr -I/usr/pkg/include/nss/nss -I/usr/pkg/include/libdrm -I/usr/pkg/include/freetype2 -I/usr/pkg/include/glib/glib-2.0 -I/usr/pkg/include/glib/gio-unix-2.0 -I/usr/pkg/lib/glib-2.0/include -I/usr/pkg/include/ffmpeg3 -Wall -Wc++11-compat -Wempty-body -Wignored-qualifiers -Woverloaded-virtual -Wpointer-arith -Wsign-compare -Wtype-limits -Wunreachable-code -Wwrite-strings -Wno-invalid-offsetof -Wc++14-compat -Wno-error=maybe-uninitialized -Wno-error=deprecated-declarations -Wno-error=array-bounds -fno-lifetime-dse -O2 -g -D_FORTIFY_SOURCE=2 -fstack-check -I/usr/include -I/usr/pkg/include -I/usr/pkg/include/nspr -I/usr/pkg/include/nss/nss -I/usr/pkg/include/libdrm -I/usr/pkg/include/freetype2 -I/usr/pkg/include/glib/glib-2.0 -I/usr/pkg/include/glib/gio-unix-2.0 -I/usr/pkg/lib/glib-2.0/include -I/usr/pkg/include/ffmpeg3 -fno-exceptions -fno-strict-aliasing -Dunix -fno-rtti -fno-exceptions -fno-math-errno -pthread -pipe -I/usr/pkg/include  -g -O2 -fomit-frame-pointer  -Wno-error=shadow  /scratch/mail/thunderbird/work/build/layout/tables/Unified_cpp_layout_tables0.cpp
In file included from /scratch/mail/thunderbird/work/build/layout/generic/Unified_cpp_layout_generic1.cpp:101:0:
/scratch/mail/thunderbird/work/thunderbird-52.5.2/mozilla/layout/generic/nsFrame.cpp: In member function 'nscoord nsIFrame::ComputeISizeValue(nsRenderingContext*, nscoord, nscoord, nscoord, const nsStyleCoord&, nsIFrame::ComputeSizeFlags)':
/scratch/mail/thunderbird/work/thunderbird-52.5.2/mozilla/layout/generic/nsFrame.cpp:5434:11: warning: 'result' may be used uninitialized in this function [-Wmaybe-uninitialized]
   nscoord result;
           ^~~~~~
In file included from /scratch/mail/thunderbird/work/build/layout/generic/Unified_cpp_layout_generic1.cpp:11:0:
/scratch/mail/thunderbird/work/thunderbird-52.5.2/mozilla/layout/generic/nsBlockFrame.cpp: In member function 'virtual nscoord nsBlockFrame::GetMinISize(nsRenderingContext*)':
/scratch/mail/thunderbird/work/thunderbird-52.5.2/mozilla/layout/generic/nsBlockFrame.cpp:704:1: internal compiler error: in refs_may_alias_p_1, at tree-ssa-alias.c:1429
 nsBlockFrame::GetMinISize(nsRenderingContext *aRenderingContext)
 ^~~~~~~~~~~~
no stack trace because unwind library not available
Please submit a full bug report,
with preprocessed source if appropriate.
See <http://www.NetBSD.org/support/send-pr.html> for instructions.


 Thomas