no warning for << versus + precedence confusion

[zygoloid]

Bugzilla Link	10703
Resolution	FIXED
Resolved on	Oct 05, 2012 16:56
Version	unspecified
OS	Linux
CC	@dwblaikie,@Weverything

Extended Description

clang produces no warnings for the following:

int x[4] = // ...
int k = x[0] << 24 + x[1] << 16 + x[2] << 8 + x[3];

This parses as:

int k = x[0] << (24 + x[1]) << (16 + x[2]) << (8 + x[3]);

Such a warning would need to be careful to not fire on:

std::cout << x[0] << 24 + x[1] << 16 + x[2] << 8 + x[3];

[Weverything]

David Blaikie fixed this in r165283 by introducing -Wshift-op-parentheses.

warning: '-' within '<<' [-Wshift-op-parentheses]
int x = y << 8 - z << 0;
~~ ^
note: place parentheses around the '-' expression
to silence this warning
int x = y << 8 - z << 0;
^
( )