https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102390
Bug ID: 102390
Summary: IMPLICIT SAVE not properly implemented
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: fortran
Assignee: unassigned at gcc dot gnu.org
Reporter: anlauf at gcc dot gnu.org
Target Milestone: ---
While working on pr102366, it became clear that we do not properly handle some
situations where the Fortran standard requires variables to be IMPLICIT SAVE.
F2018 8.5.16 SAVE attribute
(4) A variable, common block, or procedure pointer declared in the scoping unit
of a main program, module, or submodule implicitly has the SAVE attribute,
which
may be confirmed by explicit specification. If a common block has the SAVE
attribute in any other kind of scoping unit, it shall have the SAVE attribute
in every scoping unit that is not of a main program, module, or submodule.
There is code in decl.c:match_attr_spec that attempts to handle this for
modules and submodules.
However, the program
real(kind=4) :: a(10)
a=1.0
end
fails to place array a in static memory (for default values of option
-fmax-stack-var-size). As long as there is no program statement, we do
not have the proper context to set IMPLICIT_SAVE.
But even with a program statement the current gfortran will place a in static
memory unless one sets e.g. -fmax-stack-var-size=1 .
For standard conforming code and -std=f2018 (or earlier) this needs fixing.
