[cfe-dev] Does clang static analyzer UndefResultChecker.cpp has false positive?

[Anna Zaks]

I cannot reproduce this on latest clang (TOT) with or without the alpha checkers.

Also, most of the alpha checkers will have false positives and bugs.

Cheers,
Anna.

On Oct 20, 2013, at 12:57 AM, Jean Lee <xiaoyur347 at gmail.com> wrote:

> My environment:
> LLVM 3.3 + CLANG 3.3
> 
> 
> Build command:
> CHECKER="-enable-checker alpha.unix.Stream -enable-checker alpha.unix.SimpleStream -enable-checker alpha.core.SizeofPtr -enable-checker alpha.unix.cstring.BufferOverlap -enable-checker alpha.security.ArrayBoundV2 -enable-checker alpha.unix.PthreadLock"
> 
> scan-build-3.3 ${CHECKER} g++ static_analyzer.cpp -pthread
> 
> 
> 2013/10/20 Jean Lee <xiaoyur347 at gmail.com>
> #include <stdio.h>
> void FunctionFread(const char* szFile)
> {
> 	FILE *fp = fopen(szFile, "rb");
> 	if (fp == NULL)
> 	{
> 		return;
> 	}
> 	
> 	int ofs[2], len;
> 	int nReadNum = fread( ofs, sizeof(int), 2, fp );
> 
> 	if ( nReadNum != 2 )
> 	{
> 		fclose(fp);
> 		return;
> 	}
> 	
>         // warning: The left operand of '-' is a garbage value
> 	len = ofs[1] - ofs[0];
> 	printf("length=%d\n", len);
> 	fclose(fp);
> }
> 
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