[llvm] Add text file support for z/OS back in (PR #209259)

[Sean Perry via llvm-commits]

https://github.com/perry-ca created https://github.com/llvm/llvm-project/pull/209259

Support for auto conversion of text files was added to cat.py in https://github.com/llvm/llvm-project/pull/90128.  That was accidently removed in https://github.com/llvm/llvm-project/pull/204711 while removing some old win32 code.  This adds the z/OS support back in.

>From 43f21cd99c7e7e1ef349a8b8d1d83ab0332cff0f Mon Sep 17 00:00:00 2001
From: Sean Perry <perry at ca.ibm.com>
Date: Mon, 13 Jul 2026 13:53:34 -0400
Subject: [PATCH] Add text file support for z/OS back in

---
 llvm/utils/lit/lit/builtin_commands/cat.py | 27 ++++++++++++++++------
 1 file changed, 20 insertions(+), 7 deletions(-)

diff --git a/llvm/utils/lit/lit/builtin_commands/cat.py b/llvm/utils/lit/lit/builtin_commands/cat.py
index fc7d1229bc674..826cf94b1cb8e 100644
--- a/llvm/utils/lit/lit/builtin_commands/cat.py
+++ b/llvm/utils/lit/lit/builtin_commands/cat.py
@@ -65,18 +65,31 @@ def run(argv, stdin, stdout, stderr, cwd):
 
     for filename in filenames:
         path = filename
-        contents = None
         if not os.path.isabs(path):
             path = os.path.join(cwd, path)
+
+        contents = None
+        is_text = False
         try:
-            with open(path, "rb") as fileToCat:
-                contents = fileToCat.read()
-        except IOError as error:
-            error.filename = filename
-            stderr.write(str(error).encode())
-            return 1
+            fileToCat = open(filename, "r")
+            contents = fileToCat.read()
+            is_text = True
+        except:
+            pass
+
+        if contents is None:
+            try:
+                with open(path, "rb") as fileToCat:
+                    contents = fileToCat.read()
+            except IOError as error:
+                error.filename = filename
+                stderr.write(str(error).encode())
+                return 1
+
         if show_nonprinting:
             contents = convertToCaretAndMNotation(contents)
+        elif is_text:
+            contents = contents.encode()
         stdout.write(contents)
     return 0