[llvm] [lit] Add LIT_CURRENT_TESTCASE environment variable when running tests (PR #168762)

[Andrew Haberlandt via llvm-commits]

https://github.com/ndrewh created https://github.com/llvm/llvm-project/pull/168762

I'm not aware of any way for `%run` wrapper scripts like `iosssim_run.py` ([ref](https://github.com/llvm/llvm-project/blob/d2c7c6064259320def7a74e111079725958697d4/compiler-rt/test/sanitizer_common/ios_commands/iossim_run.py#L4)) to know what testcase they are currently running. This can be useful if these wrappers need to create a (potentially remote) temporary directory for each test case.

This adds the `LIT_CURRENT_TESTCASE` environment variable to both the internal shell and the external shell, containing the full name of the current test being run.

>From 271130cc0a9dd1a4d3dfa2c1463c0e77c607c3c2 Mon Sep 17 00:00:00 2001
From: Andrew Haberlandt <ahaberlandt at apple.com>
Date: Wed, 19 Nov 2025 11:12:06 -0800
Subject: [PATCH] [lit] Add LIT_CURRENT_TESTCASE environment variable when
 running tests

---
 llvm/utils/lit/lit/TestRunner.py | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/llvm/utils/lit/lit/TestRunner.py b/llvm/utils/lit/lit/TestRunner.py
index 64148c6098327..9525320f133c6 100644
--- a/llvm/utils/lit/lit/TestRunner.py
+++ b/llvm/utils/lit/lit/TestRunner.py
@@ -1226,6 +1226,8 @@ def executeScriptInternal(
     results = []
     timeoutInfo = None
     shenv = ShellEnvironment(cwd, test.config.environment)
+    shenv.env["LIT_CURRENT_TESTCASE"] = test.getFullName()
+
     exitCode, timeoutInfo = executeShCmd(
         cmd, shenv, results, timeout=litConfig.maxIndividualTestTime
     )
@@ -1425,11 +1427,13 @@ def executeScript(test, litConfig, tmpBase, commands, cwd):
             # run on clang with no real loss.
             command = litConfig.valgrindArgs + command
 
+    env = dict(test.config.environment)
+    env["LIT_CURRENT_TESTCASE"] = test.getFullName()
     try:
         out, err, exitCode = lit.util.executeCommand(
             command,
             cwd=cwd,
-            env=test.config.environment,
+            env=env,
             timeout=litConfig.maxIndividualTestTime,
         )
         return (out, err, exitCode, None)