https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118013
Bug ID: 118013
Summary: bogus "infinite loop" warning
Product: gcc
Version: 14.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: analyzer
Assignee: dmalcolm at gcc dot gnu.org
Reporter: bruno at clisp dot org
Target Milestone: ---
Created attachment 59844
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=59844&action=edit
test case i.c
Compiling the attached file i.c with gcc 14.2.0 (without or with optimization)
produces a "warning: infinite loop". But there is no infinite loop, because:
- If at line 93, j < nsubst, line 90 has incremented i.
- If at line 93, j == nsubst, i gets incremented.
$ gcc-version -Wall -fanalyzer -S i.c
i.c: In function ‘subst_string’:
i.c:72:18: warning: infinite loop [CWE-835] [-Wanalyzer-infinite-loop]
72 | if (str[i] == '\0')
| ^
‘subst_string_list’: event 1
|
| 101 | subst_string_list (string_list_ty *slp,
| | ^~~~~~~~~~~~~~~~~
| | |
| | (1) entry to ‘subst_string_list’
|
+--> ‘subst_string’: events 2-11
|
| 52 | subst_string (const char *str,
| | ^~~~~~~~~~~~
| | |
| | (2) entry to ‘subst_string’
|......
| 72 | if (str[i] == '\0')
| | ~ ~
| | | |
| | | (3) infinite loop here
| | | (11) ...to here
| | (4) if it ever follows ‘false’ branch, it will
always do so...
| | (9) ...to here
| | (10) looping back...
| 73 | break;
| 74 | for (j = 0; j < nsubst; j++)
| | ~~~~~ ~~~~~~~~~~
| | | |
| | | (6) when ‘j >= nsubst’: always
following ‘false’ branch...
| | (5) ...to here
|......
| 93 | if (j == nsubst)
| | ~
| | |
| | (7) ...to here
| | (8) when ‘j != nsubst’: always following
‘false’ branch...
|
