<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/97482>97482</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [Clang] Diagnostic for pp directives in the body of a function-like macro could be improved
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            enhancement,
            clang:diagnostics
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          Sirraide
      </td>
    </tr>
</table>

<pre>
    The following code, which is obviously ill-formed
```c++
#define X()                                       \
#include <stdio.h>
```
results in this error
```
<source>:2:2: error: '#' is not followed by a macro parameter
    2 | #include <stdio.h>
      |  ^
```
which makes sense in a vacuum, but can be a bit confusing in cases where the `\` is so far off to the right that you don’t see it at a glance, and just seeing this error in the console is rather unhelpful...

A fix for this that I thought of is, if the token after `#` is not a macro parameter, but rather an identifier that matches a known preprocessor directive (i.e. `include`, `define`, `pragma`, ...), then we could either change the error or add a note that says something along the lines of ‘Preprocessor directives may not appear in the body of a macro’ (which I know isn’t what this is according to the grammar, but it’s what the user intended).

</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJyMVEuP2zYQ_jX0ZbCGTPmlgw6ONwvkVqA99DoiR-JkKVLgw67_fUFJ8QbNooghPyh6Zr6XiDHy4IhacfgiDq8bzMn40P7JISBr2nReP9q_DEHvrfV3dgMor0nIK9wNKwMcwXc39jnaB7C1L70PI2lRvYrqIo7Vcikhv5RruStrTT07gr-FPAvZwO-9xOH6bMBO2awJRH2NSbPfGlF__c_QZRkoZpsisINkOAKF4MOn_yy9fA6KSqv6Itf3WlFfQMiTkLWQp8La-bSKQhq6ByCMqIKHCQOOlGidUYBLEKcr_D_qleLpWnh-zmQRfMR3ihDJRSqcEG6och6LI11OoNBBR4DQcQLlXZ9jMY0dKIwU4W4oECRDUPoeruJYFTbRQ48BfN9D8vN24MEkSAYTPHwG7Z34KsW5Ek2TIBIBJ8AECINFp-ZEoNPwPcd5uwz90HtRnwqg6C2ViQGToQDZGbJTn-12u11Zz58X6Pkf6H1Yusw4vkEyPhdYvgeOZST3c9_k38kB9onCzEvWK6_i0q_OrFqtENABa3KJe6awTBoxKUMREN6dvzuYAk3BK4rRB9AcSCW-EQh55i1ty8jV2nn4tdxYIv6xngIOI67rQlY25Vcy5OBelMlWA_GMSBl0w-LSIp8PgFoDFj60QIz4KLaNlEzRGq2fFSew7CgWhX74df7jU_QRRnwsAk0T4dOj8siX8lW2p-uF7RLBb7MqwPHnSNwLqNkrjoBK-aDnDCxpGgKOIz6V5_SsjD8qCXKkgiKR06SFbNZAbHRb66ZucEPt7rRrmsOhPsqNaaU6V40-UkO9xP7Yn_pennf7w3G_q6Q6HDfcykruq1Ml5U7Kvdzujkfco1L9rj5Wu64R-4pGZLu19jZufRg2HGOmtjntz3JjsSMb56NRSnKm5Hwkl4SUQl6FlMqiG0R90YyD8zGximXv8LoJben40uUhin1lOab4MSNxsvOJe53rD6_w-mwwR36afrbpF1_67FRi714sv9Ma7iU_HQGPU_A30pscbGtSmqKoL0K-Cfk2cDK52yo_CvlW0KxfL1Pw30klId9m-lHIt0WBWyv_DQAA___df-1c">