[lit] Flush stderr manually on Windows after printing messages

When run in a git bash terminal, sys.stderr isn't flushed implicitly after printing each line. Manually flush it after each printout, to avoid getting broken/misordered output. A similar fix had been done in the old libcxx test config, committed as part of 7e3ee09 / D28725; this generalizes the fix, making it available in the new libcxx test configs too, and for any other test that uses lit_config.note(). Differential Revision: https://reviews.llvm.org/D115761
intel · Dec 18, 2021 · 2ec75a0 · 2ec75a0
1 parent 982604c
commit 2ec75a0
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Showing 2 changed files with 5 additions and 1 deletion.
diff --git a/libcxx/utils/libcxx/test/config.py b/libcxx/utils/libcxx/test/config.py
@@ -159,7 +159,6 @@ def print_config_info(self):
         self.lit_config.note("Running against the C++ Library at {}".format(self.cxx_runtime_root))
         self.lit_config.note("Linking against the ABI Library at {}".format(self.abi_library_root))
         self.lit_config.note("Running against the ABI Library at {}".format(self.abi_runtime_root))
-        sys.stderr.flush()  # Force flushing to avoid broken output on Windows
 
     def get_test_format(self):
         from libcxx.test.format import LibcxxTestFormat

diff --git a/llvm/utils/lit/lit/LitConfig.py b/llvm/utils/lit/lit/LitConfig.py
@@ -169,6 +169,11 @@ def _write_message(self, kind, message):
         line = inspect.getlineno(f)
         sys.stderr.write('%s: %s:%d: %s: %s\n' % (self.progname, file, line,
                                                   kind, message))
+        if self.isWindows:
+            # In a git bash terminal, the writes to sys.stderr aren't visible
+            # on screen immediately. Flush them here to avoid broken/misoredered
+            # output.
+            sys.stderr.flush()
 
     def note(self, message):
         if not self.quiet: