[clang] [llvm] [CMake] Move check for dlfcn.h and dladdr to clang (PR #76163)

[Abhina Sree via cfe-commits]

https://github.com/abhina-sree created https://github.com/llvm/llvm-project/pull/76163

This patch checks for the presence of dlfcn.h and dladdr in clang to be used in clang/tools/libclang/CIndexer.cpp

>From 37a33f4f2458ed32cd0c53834044410c9a90c07f Mon Sep 17 00:00:00 2001
From: Abhina Sreeskantharajan <Abhina.Sreeskantharajan at ibm.com>
Date: Thu, 21 Dec 2023 08:28:30 -0500
Subject: [PATCH 1/2] Revert "Use llvm-config.h in CIndexer.cpp instead of
 private header (#75928)"

This reverts commit e86a02ce89c33f3fa4061fb4c67c3b05c69a72ab.
---
 clang/tools/libclang/CIndexer.cpp            | 2 +-
 llvm/include/llvm/Config/config.h.cmake      | 6 ++++++
 llvm/include/llvm/Config/llvm-config.h.cmake | 6 ------
 3 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/clang/tools/libclang/CIndexer.cpp b/clang/tools/libclang/CIndexer.cpp
index 430147b2aa77af..0623ae69fe01ed 100644
--- a/clang/tools/libclang/CIndexer.cpp
+++ b/clang/tools/libclang/CIndexer.cpp
@@ -17,7 +17,7 @@
 #include "clang/Driver/Driver.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallString.h"
-#include "llvm/Config/llvm-config.h"
+#include "llvm/Config/config.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/MD5.h"
 #include "llvm/Support/Path.h"
diff --git a/llvm/include/llvm/Config/config.h.cmake b/llvm/include/llvm/Config/config.h.cmake
index d464263c190a73..fc1f9bf342f8d5 100644
--- a/llvm/include/llvm/Config/config.h.cmake
+++ b/llvm/include/llvm/Config/config.h.cmake
@@ -50,9 +50,15 @@
    don't. */
 #cmakedefine01 HAVE_DECL_STRERROR_S
 
+/* Define to 1 if you have the <dlfcn.h> header file. */
+#cmakedefine HAVE_DLFCN_H ${HAVE_DLFCN_H}
+
 /* Define if dlopen() is available on this platform. */
 #cmakedefine HAVE_DLOPEN ${HAVE_DLOPEN}
 
+/* Define if dladdr() is available on this platform. */
+#cmakedefine HAVE_DLADDR ${HAVE_DLADDR}
+
 /* Define to 1 if we can register EH frames on this platform. */
 #cmakedefine HAVE_REGISTER_FRAME ${HAVE_REGISTER_FRAME}
 
diff --git a/llvm/include/llvm/Config/llvm-config.h.cmake b/llvm/include/llvm/Config/llvm-config.h.cmake
index 483c5adc99ca80..6605ea60df99e1 100644
--- a/llvm/include/llvm/Config/llvm-config.h.cmake
+++ b/llvm/include/llvm/Config/llvm-config.h.cmake
@@ -198,10 +198,4 @@
 /* Define if plugins enabled */
 #cmakedefine LLVM_ENABLE_PLUGINS
 
-/* Define to 1 if you have the <dlfcn.h> header file. */
-#cmakedefine HAVE_DLFCN_H ${HAVE_DLFCN_H}
-
-/* Define if dladdr() is available on this platform. */
-#cmakedefine HAVE_DLADDR ${HAVE_DLADDR}
-
 #endif

>From c21d00f03428154d7c1f2bee9a47bfd031ed476a Mon Sep 17 00:00:00 2001
From: Abhina Sreeskantharajan <Abhina.Sreeskantharajan at ibm.com>
Date: Thu, 21 Dec 2023 10:43:05 -0500
Subject: [PATCH 2/2] detect dlfcn.h and dladdr in clang

---
 clang/CMakeLists.txt                      | 17 +++++++++++++++++
 clang/include/clang/Config/config.h.cmake |  6 ++++++
 clang/tools/libclang/CIndexer.cpp         |  4 ++--
 3 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/clang/CMakeLists.txt b/clang/CMakeLists.txt
index 2ca6db02e58791..9f814478c45503 100644
--- a/clang/CMakeLists.txt
+++ b/clang/CMakeLists.txt
@@ -167,6 +167,23 @@ endif()
 include(CheckIncludeFile)
 check_include_file(sys/resource.h CLANG_HAVE_RLIMITS)
 
+# This check requires _GNU_SOURCE on linux
+check_include_file(dlfcn.h CLANG_HAVE_DLFCN_H)
+if( CLANG_HAVE_DLFCN_H )
+  include(CheckLibraryExists)
+  include(CheckSymbolExists)
+  check_library_exists(dl dlopen "" HAVE_LIBDL)
+  if( HAVE_LIBDL )
+    list(APPEND CMAKE_REQUIRED_LIBRARIES dl)
+  endif()
+  list(APPEND CMAKE_REQUIRED_DEFINITIONS -D_GNU_SOURCE)
+  check_symbol_exists(dladdr dlfcn.h CLANG_HAVE_DLADDR)
+  list(REMOVE_ITEM CMAKE_REQUIRED_DEFINITIONS -D_GNU_SOURCE)
+  if( HAVE_LIBDL )
+    list(REMOVE_ITEM CMAKE_REQUIRED_LIBRARIES dl)
+  endif()
+endif()
+
 set(CLANG_RESOURCE_DIR "" CACHE STRING
   "Relative directory from the Clang binary to its resource files.")
 
diff --git a/clang/include/clang/Config/config.h.cmake b/clang/include/clang/Config/config.h.cmake
index a54a26cd32ffe4..4015ac8040861c 100644
--- a/clang/include/clang/Config/config.h.cmake
+++ b/clang/include/clang/Config/config.h.cmake
@@ -57,6 +57,12 @@
 /* Define if we have sys/resource.h (rlimits) */
 #cmakedefine CLANG_HAVE_RLIMITS ${CLANG_HAVE_RLIMITS}
 
+/* Define if we have dlfcn.h */
+#cmakedefine CLANG_HAVE_DLFCN_H ${CLANG_HAVE_DLFCN_H}
+
+/* Define if dladdr() is available on this platform. */
+#cmakedefine CLANG_HAVE_DLADDR ${CLANG_HAVE_DLADDR}
+
 /* Linker version detected at compile time. */
 #cmakedefine HOST_LINK_VERSION "${HOST_LINK_VERSION}"
 
diff --git a/clang/tools/libclang/CIndexer.cpp b/clang/tools/libclang/CIndexer.cpp
index 0623ae69fe01ed..12d9d418dea51d 100644
--- a/clang/tools/libclang/CIndexer.cpp
+++ b/clang/tools/libclang/CIndexer.cpp
@@ -14,10 +14,10 @@
 #include "CXString.h"
 #include "clang/Basic/LLVM.h"
 #include "clang/Basic/Version.h"
+#include "clang/Config/config.h"
 #include "clang/Driver/Driver.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallString.h"
-#include "llvm/Config/config.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/MD5.h"
 #include "llvm/Support/Path.h"
@@ -127,7 +127,7 @@ const std::string &CIndexer::getClangResourcesPath() {
   getClangResourcesPathImplAIX(LibClangPath);
 #else
   bool PathFound = false;
-#if defined(HAVE_DLFCN_H) && defined(HAVE_DLADDR)
+#if defined(CLANG_HAVE_DLFCN_H) && defined(CLANG_HAVE_DLADDR)
   Dl_info info;
   // This silly cast below avoids a C++ warning.
   if (dladdr((void *)(uintptr_t)clang_createTranslationUnit, &info) != 0) {