[RFC] Replacing special goto statements by direct returns?

[Markus Elfring]

Hello,

The documentation for the Linux coding style contains the following information.
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/coding-style.rst?h=v7.4-rc1#n526

“…
The goto statement comes in handy when a function exits from multiple
locations and some common work such as cleanup has to be done.  If there is no
cleanup needed then just return directly.
…”


Thus it seems that the following script for the semantic patch language
can work to some degree.


@replacement exists@
identifier label, var;
@@
-goto label;
+return var;
 ...
-label:
 return var;



Unfortunately, patches would be generated then by such a simple SmPL code
which would still preserve return statements that became unreachable.

Test result example:
Markus_Elfring@Sonne:…/Projekte/Linux/next-analyses> time spatch --allow-inconsistent-paths fs/xfs/libxfs/xfs_btree.c …/Projekte/Coccinelle/janitor/replace_goto_by_return2.cocci
…
@@ -1735,7 +1735,7 @@ xfs_btree_increment(
                --lev;
                error = xfs_btree_read_buf_block(cur, ptrp, 0, &block, &bp);
                if (error)
-                       goto error0;
+                       return error;
 
                xfs_btree_setbuf(cur, lev, bp);
                cur->bc_levels[lev].ptr = 1;
@@ -1747,8 +1747,6 @@ out1:
 out0:
        *stat = 0;
        return 0;
-
-error0:
        return error;
 }
…
real    0m1,074s
user    0m0,995s
sys     0m0,071s



How should such a source code transformation approach be improved accordingly?

Regards,
Markus