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From: Derek M Jones <derek@knosof.co.uk>
To: cocci@inria.fr
Subject: [cocci] ChatGPT 4 and Coccinelle
Date: Wed, 15 May 2024 01:44:29 +0100	[thread overview]
Message-ID: <233b3043-2539-42f4-b47a-771b0094b558@knosof.co.uk> (raw)

Julia,

Our LLM overlords can create Coccinelle scripts.
We are doomed!


Derek
write a coccinelle pattern to match an if statement containing a single variable

ChatGPT 4

To create a Coccinelle semantic patch (spatch) to match an if statement in C code that contains a single variable, you 
can write a pattern that specifically looks for if statements and then checks if the condition inside the if statement 
consists solely of a single variable. Here’s a basic example of how you can define such a pattern using Coccinelle's 
transformation language:

coccinelle

@@
identifier var;
@@

if (var)
   ...

Here's a brief explanation of each part of this semantic patch:

1.  @@: This symbol marks the start of a rule definition in Coccinelle. Everything between two @@ symbols constitutes 
one rule.

2.  identifier var;: This line declares a metavariable named var that stands for any identifier in the code. In 
Coccinelle, metavariables allow you to abstract parts of the code so that your rules can match more generally without 
hardcoding specific variable names.

3.  if (var): This line specifies the pattern to match—an if statement where the condition is exactly the identifier 
captured by var.

4.  ...: The ellipsis (...) in Coccinelle matches any code. In this context, it means that anything can follow the if 
statement, without specifying what must be inside the if block.

This simple semantic patch will match any if statement where the condition consists of a single variable, regardless of 
what that variable is or what code follows within the if block.
To Apply This Patch:

You would need to save the above code to a file with a .cocci extension, for example, single_var_if.cocci. Then you 
would run the Coccinelle tool on your source code directory like this:

bash

spatch --sp-file single_var_if.cocci --dir your_source_code_directory

This command will apply the single_var_if.cocci semantic patch to all the C files in your_source_code_directory, showing 
where if statements with a single variable condition occur.

For further customization or to make more complex patterns, you can refer to the Coccinelle documentation or look into 
more examples of Coccinelle semantic patches which can be found in various open-source projects and documentation resources.

-- 
Derek M. Jones           Evidence-based software engineering
blog:https://shape-of-code.com

next             reply	other threads:[~2024-05-15  0:44 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-05-15  0:44 Derek M Jones [this message]
2024-05-15  6:00 ` [cocci] ChatGPT 4 and Coccinelle Julia Lawall
2024-05-15  9:08   ` Derek M Jones
2024-05-15  9:13     ` Julia Lawall
2024-05-15  7:30 ` Markus Elfring

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