[LLVMbugs] [Bug 3333] New: No warning when shifting invalid amount

bugzilla-daemon at cs.uiuc.edu bugzilla-daemon at cs.uiuc.edu
Thu Jan 15 11:43:34 PST 2009


           Summary: No warning when shifting invalid amount
           Product: clang
           Version: unspecified
          Platform: PC
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: Semantic Analyzer
        AssignedTo: unassignedclangbugs at nondot.org
        ReportedBy: alexei.svitkine at gmail.com
                CC: llvmbugs at cs.uiuc.edu

When using operators ">>" or "<<", the valid range for the shift amount is [0,
# bits in type).

GCC gives appropriate warnings when the shift amount is an out-of-range
constant, such as:

"warning: right shift count is negative"


"warning: left shift count >= width of type"

However, clang does not present any warnings on the same code. An example

#include <stdio.h>

int main(void)
        int i = 1;
        printf("%d\n", i>>-1);
        return 0;

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