# Warning: ‘.str’ may be used uninitialized **URL:** \ **Category:** Uncategorized\ **Created:** [April 10, 2023, 4:41am UTC](https://fortran-lang.discourse.group/t/warning-str-may-be-used-uninitialized/5539 "2023-04-10T04:41:50Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![zaikunzhang](https://yyz2.discourse-cdn.com/free1/user_avatar/fortran-lang.discourse.group/zaikunzhang/32/785_2.png) [@zaikunzhang](https://fortran-lang.discourse.group/u/zaikunzhang)\ **Post date:** [April 10, 2023, 4:41am UTC](https://fortran-lang.discourse.group/t/warning-str-may-be-used-uninitialized/5539/1 "2023-04-10T04:41:50Z")
Code: ```auto ! test_char.f90 program test_char implicit none character(len=:), allocatable :: str str = 'hello world' end program test_char ``` Test: ```auto $ gfortran --version && gfortran -g -Wall -std=f2018 test_char.f90 GNU Fortran (Ubuntu 11.3.0-1ubuntu1~22.04) 11.3.0 test_char.f90:9:19: 9 | str = 'hello world' | ^ Warning: ‘.str’ may be used uninitialized [-Wmaybe-uninitialized] ``` **Questions** : 1. Is the code standard-conforming? 2. Why `str` is considered maybe uninitialized? 3. What is the dot preceding `str`? **Remarks** 1. I am aware that `-Wall` implies `-Wmaybe-uninitialized`. What interests me is not why this option is turned on or whether it should be, but rather why the code triggers this warning. 2. The following compilation finishes without warning. ```auto ifort -g -warn all -check all -debug extended test_char.f90 ifx -g -warn all -check all -debug extended test_char.f90 nagfor -g -C test_char.f90 flang -g -Wall -Wextra test_char.f90 nvfortran -g -Wall -Wextra test_char.f90 aocc-flang -g -Wall -Wextra test_char.f90 sunf95 -g -w3 -ansi -xcheck=%all -C test_char.f90 ``` Thanks. ---
**Author:** ![band-a-prend](https://avatars.discourse-cdn.com/v4/letter/b/7c8e57/32.png) [@band-a-prend](https://fortran-lang.discourse.group/u/band-a-prend)\ **Post date:** [April 10, 2023, 10:29am UTC](https://fortran-lang.discourse.group/t/warning-str-may-be-used-uninitialized/5539/2 "2023-04-10T10:29:41Z")
It seems it’s a gfortran issue [91442 – Wrong "may be used uninitialized" warning with allocation on assignment](https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91442) (or even early [56670 – Allocatable-length character var causes bogus warning with -Wuninitialized](https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56670)) As mentioned there the addition of optimization key e.g. ‘-O2’ removes this warning. ---
**Author:** ![zaikunzhang](https://yyz2.discourse-cdn.com/free1/user_avatar/fortran-lang.discourse.group/zaikunzhang/32/785_2.png) [@zaikunzhang](https://fortran-lang.discourse.group/u/zaikunzhang)\ **Post date:** [April 10, 2023, 4:11pm UTC](https://fortran-lang.discourse.group/t/warning-str-may-be-used-uninitialized/5539/3 "2023-04-10T16:11:56Z")
Thank you @band-a-prend for the information. ---
**Author:** ![Beliavsky](https://avatars.discourse-cdn.com/v4/letter/b/ba8739/32.png) [@Beliavsky](https://fortran-lang.discourse.group/u/Beliavsky)\ **Post date:** [April 10, 2023, 5:21pm UTC](https://fortran-lang.discourse.group/t/warning-str-may-be-used-uninitialized/5539/4 "2023-04-10T17:21:25Z")
A related thread was [Gfortran uninitialized warnings](https://fortran-lang.discourse.group/t/gfortran-uninitialized-warnings/3838). These warnings of gfortran are sometimes spurious, so I turn them off. ---
**Author:** ![nbehrnd](https://avatars.discourse-cdn.com/v4/letter/n/e0b2c6/32.png) [@nbehrnd](https://fortran-lang.discourse.group/u/nbehrnd)\ **Post date:** [April 13, 2023, 8:25pm UTC](https://fortran-lang.discourse.group/t/warning-str-may-be-used-uninitialized/5539/5 "2023-04-13T20:25:34Z")
With copy-paste of your code and a more recent / contemporary release of gfortran 12.2.0 as provided by Linux Debian 12/bookworm (currently branch testing), I do not observe an error warning. To quote the CLI ```plaintext $ gfortran --version && gfortran -g -Wall -std=f2018 test_char.f90 GNU Fortran (Debian 12.2.0-14) 12.2.0 Copyright (C) 2022 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. ``` ---
**Author:** ![zaikunzhang](https://yyz2.discourse-cdn.com/free1/user_avatar/fortran-lang.discourse.group/zaikunzhang/32/785_2.png) [@zaikunzhang](https://fortran-lang.discourse.group/u/zaikunzhang)\ **Post date:** [April 15, 2023, 4:40am UTC](https://fortran-lang.discourse.group/t/warning-str-may-be-used-uninitialized/5539/6 "2023-04-15T04:40:59Z")
Thank you @nbehrnd . The same on my side. It is great to see the bug fixed in gfortran-12.