https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98900
Bug ID: 98900
Summary: Wrong static analyses warning when optimisation is on
Product: gcc
Version: 8.3.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: oleg.pekar.2017 at gmail dot com
Target Milestone: ---
Created attachment 50095
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=50095&action=edit
Preprocessor output for source file test1.c
gcc version: 8.3.1
system type: RedHat 8.1, Kernel 4.18.0-147.3.1.el8_1.x86_64
Problem: Wrong static analyses warning when optimisation is on.
Input source: attached test1.i
Description: in this code address of a variable local to a block is used
outside of the block. With no optimisation there's no warning while the code
still can cause a problem. But with optimisation static analyses provides a
confusing warning - it complains about a variable not used in the context of
the warning.
Command line with no optimisation: gcc -Wall -save-temps test1.c
Output: nothing
Command line with optimisation: gcc -Wall -save-temps -O2 test1.c
Output:
test1.c: In function ‘main’:
test1.c:11:7: warning: ‘x’ is used uninitialized in this function
[-Wuninitialized]
g = *p;
~~^~~~
