[libc] Use a sensible default when TEST_UNDECLARED_OUTPUTS_DIR is unset.

[Sterling-Augustine]

There is no guarantee that this environment variable is set. Eg, when running a test outside of the build system, such as under a debugger. And passing a nullptr to the string constructor is undefined.

Use an empty string, which seems like it is close to the original intent.

[llvmbot]

@llvm/pr-subscribers-libc

Author: None (Sterling-Augustine)

Changes

There is no guarantee that this environment variable is set. Eg, when running a test outside of the build system, such as under a debugger. And passing a nullptr to the string constructor is undefined.

Use an empty string, which seems like it is close to the original intent.

---

Full diff: https://github.com/llvm/llvm-project/pull/167422.diff

1 Files Affected:

• (modified) libc/test/UnitTest/BazelFilePath.cpp (+4)

diff --git a/libc/test/UnitTest/BazelFilePath.cpp b/libc/test/UnitTest/BazelFilePath.cpp
index ee5fcaaa63d91..7f9f42b46dca9 100644
--- a/libc/test/UnitTest/BazelFilePath.cpp
+++ b/libc/test/UnitTest/BazelFilePath.cpp
@@ -20,6 +20,10 @@ namespace testing {
 CString libc_make_test_file_path_func(const char *file_name) {
   // This is the path to the folder bazel wants the test outputs written to.
   const char *UNDECLARED_OUTPUTS_PATH = getenv("TEST_UNDECLARED_OUTPUTS_DIR");
+  // Do something sensible if not run under bazel, otherwise this may segfault
+  // when constructing the string.
+  if (UNDECLARED_OUTPUTS_PATH == nullptr)
+    UNDECLARED_OUTPUTS_PATH = "";
 
   return cpp::string(UNDECLARED_OUTPUTS_PATH) + file_name;
 }

[michaelrj-google]

This shouldn't be necessary, this file is only built under the bazel build. For cmake we use CmakeFilePath.cpp

[Sterling-Augustine]

This shouldn't be necessary, this file is only built under the bazel build. For cmake we use CmakeFilePath.cpp

If you run the bazel-built test under gdb (as I did while working on #167350) it will segfault.

[michaelrj-google]

Ah, that makes sense. LGTM