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Thunderbird From: Markus Elfring Subject: Re: [cocci] [1/36] coccinelle: misc: add cond_return_no_effect.cocci To: Julia Lawall , cocci@inria.fr Cc: Sang-Heon Jeon , Nicolas Palix , LKML , kernel-janitors@vger.kernel.org References: <20260723184538.3888637-1-ekffu200098@gmail.com> <20260723184538.3888637-2-ekffu200098@gmail.com> <514fd536-291a-bfad-fac8-15e0d0611689@inria.fr> <077ae2e1-c471-4e87-9d40-caddd3a8a358@web.de> <6a456a1a-3c5f-5514-486a-9e3f9d1361a4@inria.fr> Content-Language: en-GB, de-DE In-Reply-To: <6a456a1a-3c5f-5514-486a-9e3f9d1361a4@inria.fr> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K1:9DCvdkpDFtBQpA5TuxMRR2jt4Wwjh8NjIRGP0LZE7lZQVGEaZ3K HnbhIdHBHR/ylxFfZJCujfPOq9nJcyAtP/R/v9VICgCQju33bcSSXw35KYf+Dxsjrg0kmin q/34XywCre+m+uRc21sbrC0Vp1BNRulRbd4pdek1onsnwVhl+XC/50n4Eh2yiIiD9UjdNA7 ib6o4K5MDYGZIeUw0vJgQ== X-Spam-Flag: NO UI-OutboundReport: notjunk:1;M01:P0:r4+1/bTiZiQ=;CngKwYpNZLos6ZI5b3eXDWvHMWq 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bq9TfNaX3xN4fEMHU+qhx8vnDkEmsqZL4m8B9CVbbVKMB5NAWJNOTLhfq6ZT6Ece8HDt6ZvJ+ uk/nyyBgXNUHNG4M1pc5FXynQGvwSd3GF7xkGPziYzNESpD4bG+2Rmb/4S+wmg7R+RS7ukADZ t7B5FICJZ0cdBJFUTDqQD >> I would appreciate to clarify such an approach for a bit of dead-code e= limination >> in more detail. >=20 > I have no idea what you are talking about. What dead code are you > referring to? Variable definitions which became unused according to transformation rules by the semantic patch language. https://en.wikipedia.org/wiki/Dead-code_elimination >> I got the impression that some versions of the C programming language d= o >> not handle variable declarations also as =E2=80=9Cstatements=E2=80=9D. >> https://en.cppreference.com/c/language/statements >> >> See also: >> https://en.cppreference.com/cpp/language/statements#Declaration_stateme= nts >=20 > And the conclusion would be what? First, Coccinelle has it's own parser= . This is generally fine. > It decides what is a statement, not some wikipedia page. Does your supported data model deviate from known programming language sta= ndard specifications? Can users determine relevant differences from published software documenta= tion? > Second, Coccinelle does not consider declarations to be statements. > That's what the D is there for. You suggested to apply two metavariable types in an SmPL disjunction while trying to delete special variable definitions, didn't you? >>> The first part ensures that it is not a top-level declaration and the >>> second part does the check you had previously. >> >> I do not see so far that the intended source code restriction would be = explicitly >> expressed here. >=20 > No idea what this means. What intended code restriction are you referri= ng to? Do you try to distinguish global variable declarations from local definiti= ons anyhow? How are variable scopes be taken into account here? https://github.com/coccinelle/coccinelle/issues/322 Regards, Markus