Opened 9 years ago
Closed 9 years ago
#9596 closed Patches (fixed)
"logical ‘and’ of mutually exclusive tests is always false" error in random/linear_congruential.hpp
| Reported by: | Owned by: | No-Maintainer | |
|---|---|---|---|
| Milestone: | To Be Determined | Component: | random |
| Version: | Boost 1.55.0 | Severity: | Optimization |
| Keywords: | Cc: |
Description
There is a line in random/linear_congruential.hpp at line 136 which seems to work, but may be a bit wrong. It may definitely be my somewhat small knowledge of how the compiler works, but shouldn't this: if(_x <= 0 && _x != 0) be equal to if(_x < 0). This line throws an error with the -Werror flag set in gcc 4.7.2: with "logical ‘and’ of mutually exclusive tests is always false [-Werror=logical-op]". These are not mutually exclusive, so the compiler may be wrong, but the question still remains if this could be done better.
Change History (2)
comment:1 by , 9 years ago
comment:2 by , 9 years ago
| Resolution: | → fixed |
|---|---|
| Status: | new → closed |
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The tests are mutually exclusive for unsigned types. The problem is that the expression is always false for unsigned type, but is needed for signed types. When I wrote it, using _x <= 0 && x != 0 was sufficient to avoid a warning, but apparently that's no longer the case.