[gcc r17-2772] contrib: add support for tabs in the middle of the line

https://gcc.gnu.org/g:5dfea15a44343841a5d3d18ee736eaeb4f48fb1d

commit r17-2772-g5dfea15a44343841a5d3d18ee736eaeb4f48fb1d
Author: Torbjörn SVENSSON <[email protected]>
Date:   Tue Jul 28 22:15:28 2026 +0200

    contrib: add support for tabs in the middle of the line
    
    When running the style checker, it can incorrectly, report an error for
    too wide lines if the tab is not at the start of the line.
    In below example, I'm using ^I to visualise a tab.
    
      bool begun;^I^I^I^I/* True if begin initialized output state.  */
    
    Without this patch, the line above is reported to be longer than 80
    characters, but it's only 78 characters long.  With the patch, its
    correct length is used and the check passes.
    
    contrib/ChangeLog:
    
            * check_GNU_style_lib.py: Use visual tab size rather than
            blindly using 8 spaces as replacement.
    
    Signed-off-by: Torbjörn SVENSSON <[email protected]>

Diff:
---
 contrib/check_GNU_style_lib.py | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/contrib/check_GNU_style_lib.py b/contrib/check_GNU_style_lib.py
index a7c4e2b0bd55..d057faa51cd3 100755
--- a/contrib/check_GNU_style_lib.py
+++ b/contrib/check_GNU_style_lib.py
@@ -78,10 +78,9 @@ class CheckError:
 class LineLengthCheck:
     def __init__(self):
         self.limit = 80
-        self.expanded_tab = ' ' * ts
 
     def check(self, filename, lineno, line):
-        line_expanded = line.replace('\t', self.expanded_tab)
+        line_expanded = line.expandtabs(ts)
         if not filename.endswith(".opt") and len(line_expanded) > self.limit:
             return CheckError(filename, lineno,
                 line_expanded[:self.limit]