[lit] Remove python 2.7 code paths in builtin diff

[boomanaiden154]

Lit's builtin diff command had some Python 2.7 code paths lying around
that we can probably get rid of at this point. LLVM at this point
requires Python 3.8 at minimum. Keeping lit working at a lower version
is a reasonable goal, but I think we can probably drop python 2 support
at this point given how long it has been deprecated and how long LLVM
has supported Python 3.

[llvmbot]

@llvm/pr-subscribers-testing-tools

Author: Aiden Grossman (boomanaiden154)

Changes

Lit's builtin diff command had some Python 2.7 code paths lying around
that we can probably get rid of at this point. LLVM at this point
requires Python 3.8 at minimum. Keeping lit working at a lower version
is a reasonable goal, but I think we can probably drop python 2 support
at this point given how long it has been deprecated and how long LLVM
has supported Python 3.

---

Full diff: https://github.com/llvm/llvm-project/pull/157558.diff

1 Files Affected:

• (modified) llvm/utils/lit/lit/builtin_commands/diff.py (+10-31)

diff --git a/llvm/utils/lit/lit/builtin_commands/diff.py b/llvm/utils/lit/lit/builtin_commands/diff.py
index fbf4eb0e137b3..f2b5869b35889 100644
--- a/llvm/utils/lit/lit/builtin_commands/diff.py
+++ b/llvm/utils/lit/lit/builtin_commands/diff.py
@@ -59,30 +59,15 @@ def compareTwoFiles(flags, filepaths):
 
 def compareTwoBinaryFiles(flags, filepaths, filelines):
     exitCode = 0
-    if hasattr(difflib, "diff_bytes"):
-        # python 3.5 or newer
-        diffs = difflib.diff_bytes(
-            difflib.unified_diff,
-            filelines[0],
-            filelines[1],
-            filepaths[0].encode(),
-            filepaths[1].encode(),
-            n=flags.num_context_lines,
-        )
-        diffs = [diff.decode(errors="backslashreplace") for diff in diffs]
-    else:
-        # python 2.7
-        if flags.unified_diff:
-            func = difflib.unified_diff
-        else:
-            func = difflib.context_diff
-        diffs = func(
-            filelines[0],
-            filelines[1],
-            filepaths[0],
-            filepaths[1],
-            n=flags.num_context_lines,
-        )
+    diffs = difflib.diff_bytes(
+        difflib.unified_diff,
+        filelines[0],
+        filelines[1],
+        filepaths[0].encode(),
+        filepaths[1].encode(),
+        n=flags.num_context_lines,
+    )
+    diffs = [diff.decode(errors="backslashreplace") for diff in diffs]
 
     for diff in diffs:
         sys.stdout.write(to_string(diff))
@@ -230,14 +215,8 @@ def compareDirTrees(flags, dir_trees, base_paths=["", ""]):
 
 def main(argv):
     if sys.platform == "win32":
-        if hasattr(sys.stdout, "buffer"):
-            # python 3
-            sys.stdout = io.TextIOWrapper(sys.stdout.buffer, newline="\n")
-        else:
-            # python 2.7
-            import msvcrt
+        sys.stdout = io.TextIOWrapper(sys.stdout.buffer, newline="\n")
 
-            msvcrt.setmode(sys.stdout.fileno(), os.O_BINARY)
     args = argv[1:]
     try:
         opts, args = getopt.gnu_getopt(args, "wbuI:U:r", ["strip-trailing-cr"])

[ilovepi]

This seems fine to me, especially since it follows our written policy on version support.

Does this need any kind of release note? It's a pure dev dependency, so I'd say "no", but I could also see how a consumer would have wanted to know about it.

[boomanaiden154]

Does this need any kind of release note? It's a pure dev dependency, so I'd say "no", but I could also see how a consumer would have wanted to know about it.

It doesn't hurt to add one, so I'll throw one in.