------- Comment #4 from burnus at gcc dot gnu dot org 2009-10-21 14:07 -------
While for
goto 99
if(.true.) then
99 continue
end if
end
one gets (for if, do, select case) the nice warning (!) message:
Warning: Label at (1) is not in the same block as the GOTO statement at (2)
One gets for
goto 99
block
99 continue
end block
end
only:
Error: Label 99 referenced at (1) is never defined
I think something nicer than "never defined" would be useful. One has also to
think about which of those should give a warning (like now) and which should
give a hard error.
I believe jumping *into* a (DO/IF/SELECT (TYPE/CASE)/BLOCK/ ...) block is
invalid, but they are all in the same scoping unit. However, I failed to find
this restriction.
The standard has:
R851 goto-stmt is GO TO label
C846 (R851) The label shall be the statement label of a branch target
statement that appears in the same scoping unit as the goto-stmt.
1.3.115 scoping unit
either
- a program unit or subprogram, excluding any scoping units in it,
- a derived-type de nition (4.5.2), or
- an interface body, excluding any scoping units in it
Further restrictions (and some more related to branching to an END <x> only
from inside of the <x>):
C734 (R744) A statement that is part of a where-body-construct shall not be a
branch target statement.
C743 (R756) A forall-body-construct shall not be a branch target.
It is permissible to branch to an end-associate-stmt only from within its
ASSOCIATE construct.
C811 A statement that branches from the block of a critical-construct to
outside the critical-construct is not permitted. A CYCLE or EXIT statement in a
critical-construct that transfers control outside the critical-construct is not
permitted.
It is permitted to branch to the end-do of a block DO construct only from
within the range of that DO construct.
C824 A branch (8.2) within a DO CONCURRENT construct shall not have a branch
target that is outside the construct.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41781
