build with gcc6 broken
----------------------
Key: CORE-5099
URL: http://tracker.firebirdsql.org/browse/CORE-5099
Project: Firebird Core
Issue Type: Bug
Components: Build Issues / Porting
Affects Versions: 2.5.5, 3.0 RC1
Environment: x86_64 Linux with gcc6 (openSUSE Tumbleweed) but should
be the same on any platform with gcc6
Reporter: Michal Kubeček
Priority: Minor
Note: it will still take some time for gcc6 to reach distributions so this is
not really urgent but it would be nice to be prepared.
Main change is default C++ standard: while gcc4 and gcc5 default to
-std=gnu++98 (C++98 with some GNU specific extensions), gcc6 defaults to
-std=gnu++14 (C++14 with some GNU extensions). This brings some changes, some
subtle, some less so. Now when we have a staging project in BuildService, I
tried to address some of them (first in 2.5 but 3.0 seems to be show the same
problems).
1. invalid implicit conversion of 'false' to 'bool*' in par_primitive_value()
(src/gpre/sqe.cpp)
A trivial mistake from replacing unsigned short with bool in 2003, fixed in 2.5
SVN recently, in 3.0 since 2011.
2. Error "declaration of operator new had different exception specifier"
(src/common/classes/alloc.cpp)
Can be either worked around by explicitely switching to C++98 mode (-std=c++98)
or (as suggested by our toolchain developers) fixed by dropping the
redeclaration in alloc.h and exception specifier in alloc.cpp. The result
builds with gcc 4.8, gcc5 and gcc6 but I'm not sure if this is OK with other
compilers (like MSVC).
For details, see https://bugzilla.suse.com/show_bug.cgi?id=964466#c4
3. Once these two are addressed, "../gen/firebird/bin/create_db empty.fdb"
fails with "invalid request BLR at offset 24"
Additional message says "Too many Contexts of Relation/Procedure/Views. Maximum
allowed is 255" which is really strange as, according to progam exit code, it
fais on isc_create_database() call. No idea so far. Another strange part is
that with "--enable-debug", the whole build succeeds (once the following issues
are also addressed).
4. Possibly undefined expression in shutdown() (src/jrd/shut.cpp)
In 'for (Attachment* attachment = attachment = dbb->dbb_attachments; ... )',
the extra '= attachment' should be dropped, I believe.
5. Warming: narrowing conversion ... inside { }
Some of these come from ODS_8_0 and friends being USHORT but used to initialize
UCHAR fields in various structures. IMHO there would be no harm to declare them
as UCHAR as they fit into 8 bits and if they didn't (ODS 16?), the implicit
conversion would be lossy.
Similar problem in get_prot_mask() (src/dudley/exe.epp) where blr array of
SCHAR is initialized with UCHAR constant (blr_end); quick fix is to declare
blr[] as UCHAR and add a cast when it's passed to isc_compile_request2().
6. warning: deleting 'void*' is undefined in Database::~Database()
(src/jrd/Database.cpp)
Tried to cast to 'SORTP*', seems to work.
7. warning: 'operator new' must not return NULL unless it is declared 'throw()'
(or -fcheck-new is in effect)
Two occurences in class pool_alloc and three in class pool_alloc_rpt (both
src/include/fb_blk.h). Adding "throw()" specifier seems to work.
8. warning: invalid suffix on literal; C++11 requires a space between literal
and string macro
In constructions like "%"SLONGFORMAT",", the macro should be separated from
string literals by a space. Non-fatal but the warnings are annoying (and make
spotting the more important issues harder). Trivial to fix, however.
Right now, most critical seems issue 3, this will need more investigation.
To minimize changes to 2.5 code, we might try building with explicit -std=c++98
but that one fails for me with strange error about the way FB_VA_COPY macro is
used in AbstractString::vprintf() (src/common/classes/fb_string.cpp).
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