http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54194
Bug #: 54194
Summary: GCC 4.8 gives misleading suggestion about arithmetic
in operand of '|'
Classification: Unclassified
Product: gcc
Version: 4.8.0
Status: UNCONFIRMED
Severity: minor
Priority: P3
Component: c++
AssignedTo: [email protected]
ReportedBy: [email protected]
Using gcc version 4.8.0 20120806 (experimental) (GCC),
Target: x86_64-unknown-linux-gnu
to compile the following code:
int main()
{
char in[4]={0}, out[6];
out[1] = in[1] & 0x0F | ((in[3] & 0x3C) << 2);
}
results in a misleading warning (misplaced caret):
$ g++-48 -c -Wall -Werror w.cc
w.cc: In function 'int main()':
w.cc:4:45: error: suggest parentheses around arithmetic in operand of '|'
[-Werror=parentheses]
out[1] = in[1] & 0x0F | ((in[3] & 0x3C) << 2);
^
The problematic operand is the left operand of '|', but the caret appears to be
pointing at the right operand.
For example, clang version 3.2 (trunk 161319) gives
$ clang++ -c -Wall -Werror w.cc
w.cc:4:16: error: '&' within '|' [-Werror,-Wbitwise-op-parentheses]
out[1] = in[1] & 0x0F | ((in[3] & 0x3C) << 2);
~~~~~~^~~~~~ ~
w.cc:4:16: note: place parentheses around the '&' expression to silence this
warning
out[1] = in[1] & 0x0F | ((in[3] & 0x3C) << 2);
^
( )
