[clang] 1943c9e - Reapply "[Clang] Enable lit internal shell by default"

[Aiden Grossman via cfe-commits]

Author: Aiden Grossman
Date: 2025-10-20T05:32:50Z
New Revision: 1943c9e9b9de4b920fb4ed9352f5721407fc01c7

URL: https://github.com/llvm/llvm-project/commit/1943c9e9b9de4b920fb4ed9352f5721407fc01c7
DIFF: https://github.com/llvm/llvm-project/commit/1943c9e9b9de4b920fb4ed9352f5721407fc01c7.diff

LOG: Reapply "[Clang] Enable lit internal shell by default"

This reverts commit 5b13d99357d5113b0ee4cde2066a024e1df58222.

Added: 
    

Modified: 
    clang/test/lit.cfg.py

Removed: 
    


################################################################################
diff  --git a/clang/test/lit.cfg.py b/clang/test/lit.cfg.py
index 29088ef367e7c..52b275c095475 100644
--- a/clang/test/lit.cfg.py
+++ b/clang/test/lit.cfg.py
@@ -18,11 +18,22 @@
 # name: The name of this test suite.
 config.name = "Clang"
 
+# TODO: Consolidate the logic for turning on the internal shell by default for all LLVM test suites.
+# See https://github.com/llvm/llvm-project/issues/106636 for more details.
+#
+# We prefer the lit internal shell which provides a better user experience on failures
+# and is faster unless the user explicitly disables it with LIT_USE_INTERNAL_SHELL=0
+# env var.
+use_lit_shell = True
+lit_shell_env = os.environ.get("LIT_USE_INTERNAL_SHELL")
+if lit_shell_env:
+    use_lit_shell = lit.util.pythonize_bool(lit_shell_env)
+
 # testFormat: The test format to use to interpret tests.
 #
 # For now we require '&&' between commands, until they get globally killed and
 # the test runner updated.
-config.test_format = lit.formats.ShTest(not llvm_config.use_lit_shell)
+config.test_format = lit.formats.ShTest(execute_external=not use_lit_shell)
 
 # suffixes: A list of file extensions to treat as test files.
 config.suffixes = [