https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109195
Bug ID: 109195
Summary: GCC Static Analyzer does not know "a+0 <= b+1" in the
true branch of if (a <= b), but knows "a+0 < b+1".
Product: gcc
Version: 13.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: analyzer
Assignee: dmalcolm at gcc dot gnu.org
Reporter: geoffreydgr at icloud dot com
Target Milestone: ---
GCC Static Analyzer does not know "a+0 <= b+1" in the true branch of if (a <=
b), but knows "a+0 < b+1".
See it live: https://godbolt.org/z/PGhfKjjWG
Input:
```c
#include <stdint.h>
#include <stdbool.h>
int main(int a, int b, int c, int d) {
if ((a<b)){
// fact
__analyzer_eval((a<=b) == true);
__analyzer_eval((a<b || a==b) == true);
// Add a positive number
__analyzer_eval( a+0 <= b+0);
__analyzer_eval( a+0 <= b+1);
__analyzer_eval( a+0 < b+1);
__analyzer_eval( 0 <= 1);
__analyzer_eval( a+1 <= b+1);
__analyzer_eval( a+0 <= b+2);
__analyzer_eval( a+0 < b+2);
__analyzer_eval( a+1 <= b+2);
__analyzer_eval( a+1 < b+2);
__analyzer_eval( a+2 <= b+2);
}
}
```
Output:
```
<source>: In function 'main':
<source>:7:9: warning: implicit declaration of function '__analyzer_eval'
[-Wimplicit-function-declaration]
7 | __analyzer_eval((a<=b) == true);
| ^~~~~~~~~~~~~~~
<source>:7:9: warning: TRUE
7 | __analyzer_eval((a<=b) == true);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
<source>:8:9: warning: TRUE
8 | __analyzer_eval((a<b || a==b) == true);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
<source>:11:9: warning: TRUE
11 | __analyzer_eval( a+0 <= b+0);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
<source>:13:9: warning: UNKNOWN
13 | __analyzer_eval( a+0 <= b+1);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
<source>:14:9: warning: TRUE
14 | __analyzer_eval( a+0 < b+1);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~
<source>:15:9: warning: TRUE
15 | __analyzer_eval( 0 <= 1);
| ^~~~~~~~~~~~~~~~~~~~~~~~
<source>:17:9: warning: TRUE
17 | __analyzer_eval( a+1 <= b+1);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
<source>:18:9: warning: UNKNOWN
18 | __analyzer_eval( a+0 <= b+2);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
<source>:19:9: warning: UNKNOWN
19 | __analyzer_eval( a+0 < b+2);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~
<source>:20:9: warning: UNKNOWN
20 | __analyzer_eval( a+1 <= b+2);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
<source>:21:9: warning: TRUE
21 | __analyzer_eval( a+1 < b+2);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~
<source>:22:9: warning: TRUE
22 | __analyzer_eval( a+2 <= b+2);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
Compiler returned: 0
```
