commit 15b67dacf3685d986bf9def2b885315a2604b4c8
author Michał Górny <mgorny@gentoo.org> Sat Nov 30 15:13:56 2019 +0100
committer Copybara-Service <copybara-worker@google.com> Fri Aug 28 11:14:57 2020 -0700
tree b5544d584388d1bf2d229250f39a4e92e6e3d020
parent f2132c2a727c0b965bef99ac13441b5a3681c07d

[libunwind] Emit dependent libraries only when detected by CMake

996e62eef75 added Linux-specific dependent libraries to libunwind
sources.  As a result, building libunwind with modern LLD on *BSD
started failing due to trying to link libdl.  Instead, add those
libraries only if they were detected by CMake.

While technically we could create a long list of systems that need -ldl
and -lpthread, maintaining a duplicate list makes little sense when
CMake needs to detect it for non-LLD systems anyway.  Remove existing
system exceptions since they should be covered by the CMake check
anyway.

Remove -D_LIBUNWIND_HAS_COMMENT_LIB_PRAGMA since it is no longer
explicitly needed, if we make the library-specific defines dependent
on presence of this pragma support.

Differential Revision: https://reviews.llvm.org/D70868

GitOrigin-RevId: 35bc5276ca31e3f0e8e87322153f410fa6224e59

CMakeLists.txt

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 25dc95c..08095d1 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -352,7 +352,12 @@
 endif()
 
 if (LIBUNWIND_HAS_COMMENT_LIB_PRAGMA)
-  add_definitions(-D_LIBUNWIND_HAS_COMMENT_LIB_PRAGMA)
+  if (LIBUNWIND_HAS_DL_LIB)
+    add_definitions(-D_LIBUNWIND_LINK_DL_LIB)
+  endif()
+  if (LIBUNWIND_HAS_PTHREAD_LIB)
+    add_definitions(-D_LIBUNWIND_LINK_PTHREAD_LIB)
+  endif()
 endif()
 
 #===============================================================================

src/AddressSpace.hpp

diff --git a/src/AddressSpace.hpp b/src/AddressSpace.hpp
index db67df4..7433476 100644
--- a/src/AddressSpace.hpp
+++ b/src/AddressSpace.hpp
@@ -27,7 +27,7 @@
 
 #if _LIBUNWIND_USE_DLADDR
 #include <dlfcn.h>
-#if defined(__unix__) && defined(__ELF__) && defined(_LIBUNWIND_HAS_COMMENT_LIB_PRAGMA)
+#if defined(__ELF__) && defined(_LIBUNWIND_LINK_DL_LIB)
 #pragma comment(lib, "dl")
 #endif
 #endif

src/RWMutex.hpp

diff --git a/src/RWMutex.hpp b/src/RWMutex.hpp
index 954e94c..fcd3f49 100644
--- a/src/RWMutex.hpp
+++ b/src/RWMutex.hpp
@@ -17,7 +17,7 @@
 #include <windows.h>
 #elif !defined(_LIBUNWIND_HAS_NO_THREADS)
 #include <pthread.h>
-#if defined(__unix__) && !defined(__ANDROID__) && defined(__ELF__) && defined(_LIBUNWIND_HAS_COMMENT_LIB_PRAGMA)
+#if defined(__ELF__) && defined(_LIBUNWIND_LINK_PTHREAD_LIB)
 #pragma comment(lib, "pthread")
 #endif
 #endif