https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96319
Bug ID: 96319
Summary: Don't warn for LOGICAL kind conversion with
-Wconversion
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: fortran
Assignee: unassigned at gcc dot gnu.org
Reporter: jb at gcc dot gnu.org
Target Milestone: ---
From
https://stackoverflow.com/questions/62937435/compilation-warning-with-gfortran-on-assignment-of-logicalc-bool-variable
Consider the program
PROGRAM boolean
USE ISO_C_BINDING
IMPLICIT NONE
LOGICAL (KIND = C_BOOL) :: cbool
INTEGER :: i, j
i = 1
j = 2
cbool = i /= j
WRITE(*,*) cbool
END PROGRAM boolean
Compiling with
gfortran boolean.f90 -o boolean -Wall
results in the warning
boolean.f90:8:11:
8 | cbool = i /= j
| 1
Warning: Possible change of value in conversion from LOGICAL(4) to LOGICAL(1)
at (1) [-Wconversion]
The warning is incorrect here as there's only one value bit in the LOGICAL
variable regardless of the kind, and thus there is no risk of losing data even
if this is a narrowing conversion.
