[SystemZ][z/OS] Add guard for dl_info and dladdr

[abhina-sree]

This patch fixes the following build error on z/OS error: unknown type name 'Dl_info' by adding a guard to check if we have dladdr.

[llvmbot]

@llvm/pr-subscribers-clang

Author: Abhina Sree (abhina-sree)

Changes

This patch fixes the following build error on z/OS error: unknown type name 'Dl_info' by adding a guard to check if we have dladdr.

---

Full diff: https://github.com/llvm/llvm-project/pull/75637.diff

1 Files Affected:

• (modified) clang/tools/libclang/CIndexer.cpp (+7-1)

diff --git a/clang/tools/libclang/CIndexer.cpp b/clang/tools/libclang/CIndexer.cpp
index 77da2e4fa5ead0..41f8a6f2dac5fb 100644
--- a/clang/tools/libclang/CIndexer.cpp
+++ b/clang/tools/libclang/CIndexer.cpp
@@ -125,13 +125,19 @@ const std::string &CIndexer::getClangResourcesPath() {
 #elif defined(_AIX)
   getClangResourcesPathImplAIX(LibClangPath);
 #else
+  bool pathNotFound = false;
+#if defined(HAVE_DLFCN_H) && defined(HAVE_DLADDR)
   Dl_info info;
   std::string Path;
   // This silly cast below avoids a C++ warning.
   if (dladdr((void *)(uintptr_t)clang_createTranslationUnit, &info) != 0) {
     // We now have the CIndex directory, locate clang relative to it.
     LibClangPath += info.dli_fname;
-  } else if (!(Path = llvm::sys::fs::getMainExecutable(nullptr, nullptr)).empty()) {
+  } else
+    pathNotFound = true;
+#endif
+  if (pathNotFound &&
+      !(Path = llvm::sys::fs::getMainExecutable(nullptr, nullptr)).empty()) {
     // If we can't get the path using dladdr, try to get the main executable
     // path. This may be needed when we're statically linking libclang with
     // musl libc, for example.

[fanbo-meng]

LGTM with nit

[nikic]

This is a private LLVM header, see the comment at the top of the file. It cannot be included in other subprojects.

You either have to export this macro from llvm-config.h, or you have to add it to clang's config.h.

[abhina-sree]

Thanks, I created a fix for it here #75928

[chapuni]

Could we take other ways? I think they don't affect external API.

1. Detect stuff in clang/Config/config.h
2. Migrate the special logic to llvm/Support.

[abhina-sree]

Could we take other ways? I think they don't affect external API.

1. Detect stuff in clang/Config/config.h
2. Migrate the special logic to llvm/Support.

Thanks, I've created a patch here that detects the header in clang's config.h. Please let me know if this is a good approach