http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57342
Bug ID: 57342
Summary: [C++11] Warning for narrowing conversion has ugly
formatting for floating point number
Product: gcc
Version: 4.9.0
Status: UNCONFIRMED
Severity: minor
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: austern at google dot com
When I compile the following code
void foo() {
int pi{3.14};
};
I get the following output:
[isolde:tmp]$ ~/root/bin/g++ -c -std=c++11 foo.cc
foo.cc: In function ‘void foo()’:
foo.cc:2:14: warning: narrowing conversion of ‘3.1400000000000001e+0’ from
‘double’ to ‘int’ inside { } [-Wnarrowing]
int pi{3.14};
^
The warning is of course correct. (Arguably it ought to be an error instead of
just a warning, but I won't quibble. The standard requires a diagnostic and
we're getting a diagnostic.) I'm filing this bug because I expect to see
"narrowing conversion of ‘3.14' from 'double' to 'int'", as opposed to
"narrowing conversion of ‘3.1400000000000001e+0' from 'double' to 'int'". Yes,
I'm sure the two forms are equivalent within the precision we're using, but one
form is human-friendly and the other isn't.
Configuration:
[isolde:tmp]$ ~/root/bin/g++ -v
Using built-in specs.
COLLECT_GCC=/usr/local/google/home/austern/root/bin/g++
COLLECT_LTO_WRAPPER=/usr/local/google/home/austern/root/libexec/gcc/x86_64-unknown-linux-gnu/4.9.0/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: ../gcc/configure --prefix=/usr/local/google/home/austern/root
--enable-languages=c++
Thread model: posix
gcc version 4.9.0 20130520 (experimental) (GCC)
[isolde:tmp]$
