Use CMake's built-in zlib finder

CMakeLists.txt

@@ -77,8 +77,9 @@ set(LFORTRAN_STATIC_BIN no CACHE BOOL "Build LFortran as a static binary")
 set(WITH_LFORTRAN_BINARY_MODFILES YES
     CACHE BOOL "Use binary modfiles")
 
-#ZLIB
-find_package(ZLIB REQUIRED)
+# Find ZLIB with our custom finder before including LLVM since the finder for LLVM
+# might search for ZLIB again and find the shared libraries instead of the static ones
+find_package(StaticZLIB REQUIRED)
 
 # LLVM
 set(WITH_LLVM no CACHE BOOL "Build with LLVM support")

cmake/FindStaticZLIB.cmake

@@ -0,0 +1,12 @@
+# Backup the original value of the requested library suffixes
+set(_CMAKE_FIND_LIBRARY_SUFFIXES ${CMAKE_FIND_LIBRARY_SUFFIXES})
+# Static libraries end with .a on Unix and .lib on Windows
+set(CMAKE_FIND_LIBRARY_SUFFIXES .a .lib)
+
+# Now use CMake's built-in ZLIB finder
+find_package(ZLIB REQUIRED)
+
+# Reset the library suffixes to the original value
+set(CMAKE_FIND_LIBRARY_SUFFIXES ${_CMAKE_FIND_LIBRARY_SUFFIXES})
+# Unset the temporary to not pollute the global namespace
+unset(_CMAKE_FIND_LIBRARY_SUFFIXES)

src/lfortran/CMakeLists.txt

@@ -72,7 +72,7 @@ if (WITH_LLVM)
     endif()
 endif()
 add_library(lfortran_lib ${SRC})
-target_link_libraries(lfortran_lib lfortran_runtime_static p::zlib)
+target_link_libraries(lfortran_lib lfortran_runtime_static ZLIB::ZLIB)
 target_include_directories(lfortran_lib BEFORE PUBLIC ${lfortran_SOURCE_DIR}/src)
 target_include_directories(lfortran_lib BEFORE PUBLIC ${lfortran_BINARY_DIR}/src)
 if (WITH_XEUS)