From 4b7781d90ead61d9478aabd6a4c229a114483679 Mon Sep 17 00:00:00 2001
From: Gereon Kremer <nafur42@gmail.com>
Date: Mon, 11 Oct 2021 10:48:09 -0700
Subject: [PATCH] Revert #7257 (#7337)

This PR reverts #7257 and restores compatibility with ancient glibc versions.
---
 cmake/ConfigureCvc5.cmake | 5 +++++
 src/CMakeLists.txt        | 8 ++++++++
 2 files changed, 13 insertions(+)

diff --git a/cmake/ConfigureCvc5.cmake b/cmake/ConfigureCvc5.cmake
index 2b8e5cedc..009e9969b 100644
--- a/cmake/ConfigureCvc5.cmake
+++ b/cmake/ConfigureCvc5.cmake
@@ -68,6 +68,11 @@ if(CVC5_WINDOWS_BUILD)
   endif()
 else()
   check_symbol_exists(clock_gettime "time.h" HAVE_CLOCK_GETTIME)
+  if(NOT HAVE_CLOCK_GETTIME)
+    unset(HAVE_CLOCK_GETTIME CACHE)
+    check_library_exists(rt clock_gettime "time.h" HAVE_CLOCK_GETTIME)
+    find_library(RT_LIBRARIES NAMES rt)
+  endif()
 endif()
 check_symbol_exists(ffs "strings.h" HAVE_FFS)
 check_symbol_exists(optreset "getopt.h" HAVE_DECL_OPTRESET)
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 4c418d928..583ce8bc5 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -1349,6 +1349,14 @@ if(ENABLE_STATIC_LIBRARY)
   target_link_libraries(cvc5-static PUBLIC GMP_STATIC)
 endif()
 
+# Add rt library
+# Note: For glibc < 2.17 we have to additionally link against rt (man clock_gettime).
+#       RT_LIBRARIES should be empty for glibc >= 2.17
+target_link_libraries(cvc5-shared PRIVATE ${RT_LIBRARIES})
+if(ENABLE_STATIC_LIBRARY)
+  target_link_libraries(cvc5-static PRIVATE ${RT_LIBRARIES})
+endif()
+
 if(ENABLE_VALGRIND)
   target_include_directories(cvc5-obj PUBLIC ${Valgrind_INCLUDE_DIR})
 endif()
-- 
2.30.2