<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/106302>106302</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [llvm-lit] Lit's built-in cat command not handling carriage returns correctly
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            new issue
      </td>
    </tr>

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

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

<pre>
    When using lit's internal shell to run [clang-tools-extra/test/clang-apply-replacements/crlf.cpp](https://github.com/llvm/llvm-project/blob/main/clang-tools-extra/test/clang-apply-replacements/crlf.cpp), the test fails. Upon further inspection, this is due to lit's built-in `cat` command not behaving the same as many systems' `cat` (e.g. Linux). It is not able to identify carriage returns (^M) in files. 

This problem was diagnosed by running `cat %S/Inputs/crlf/crlf.cpp` (in line 2 of the above file) with both the internal shell and with a Linux shell, and redirecting output to two different files. When analyzing the files with `cat -e` in the Linux shell, the following is displayed:

`cat %S/Inputs/crlf/crlf.cpp` run with Linux shell (expected output):
```
^M$
// This file intentionally uses a CRLF newlines!^M$
^M$
void foo() {^M$
  int *x = 0;^M$
}^M$
```

`cat %S/Inputs/crlf/crlf.cpp` run with lit internal shell (actual output):
```
$
// This file intentionally uses a CRLF newlines!$
$
void foo() {$
  int *x = 0;$
}$
```
This poses an issue, as the tests in this file rely on precise character offset to make text replacements.
</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJykVV2v4jYQ_TXmZUQUDCHkIQ97lyKtdPvSD_V5kkwSt44d2Q6Q_fXVOHAvl2qr7VZCIDOej3PmzBi9V50hKkX2IrLjCqfQW1fW1hhF89d-WlW2mcs_ejIweWU60CoImXtQJpAzqMH3pDUEC24yILKXWqPp1sFa7dd0DQ6FPAXyQcjTYsJx1PPa0aixpoFM8Gxyuk3qcRTZUchDH8LoxfaTkCchT50K_VQltR2EPGl9vv-sR2f_pJojV9pWQp4GVOYtzw-XIAshP0PoCdgJWlTaJ_D7aA20kws9OVDGj1QHZc1yVXlQHpqJmIg7RdWkdFgrA2Kf1hjEPoXaDgOaBowNUFGPZ6aUM3kcCNDDgGYGP_tAgxcyf3AV8kBJl8CrMtNVyCKBL4GTciisdMysGjJBtTPU6JzCjsBRmJzx7C2yn34WsgBloFWafAIiPYr00_L9G2MYna00DXBBD43CzlhPDVQz99ZwqUs5IGT2q5CnL2ac3qh7ZHApVxnQyhBIsG0EiZU9U0zOdVxU6KGyoY-2Jz0xSfECLoCXv5lstjhqlGP-TQd2CuMUGH24WGhU25IjE-4Yo3TRoJ6_3rmOliX6Dc-auGRlovkpX_SwWtsL-3OXlR81ztSwQB8Y_H5ueFJi-odUsb9XFhU1N0wsxO178NtnOcZe7m6HOCUQO8jYIpeGxYlazzB58oDw-ZfXExi6cEu8kJuPIR4PZ6saaK1lzcgCRP7ywQwcH4T8dAWxPUIqth_tIj9-PD-V_qNkaRWeVSLkAeswof4Oxv4nW-_u32bp3xh6ZOcbzCwjaGMBBpT3E0XB-7dd5BeN3it3pGewBkZHtfIEdY8O60AObNt6ikMx4F_sew3wuO6SVVNum2Jb4IrKTS53eVFkRbbqy31R0S5Pd01K7WZftJtNSxJzlAXtZFsdVqqUqdylB5lLmRVZlrSt3O9JSsqqdI9FJnYpDah0wjs6sa5bRSjlJt1vU7nSWJH28cGR0tDlDlTy--PKuNirqfNil2rlg38PE1TQ8aWKd3jLZkd4fV62LKvHNdujaTSP7j92Ym0dLxE9ryany__85sS6WbQ3YOdS_h0AAP__bBpRxw">