Support building phobos against a system copy of zlib

.github/workflows/supported_llvm_versions.yml

@@ -20,7 +20,7 @@ jobs:
             host_dc: ldc-1.19.0
             # FIXME: no usable official package available yet
             llvm_version: https://github.com/ldc-developers/llvm-project/releases/download/ldc-v18.1.8/llvm-18.1.8-linux-x86_64.tar.xz
-            cmake_flags: -DRT_SUPPORT_SANITIZERS=ON
+            cmake_flags: -DRT_SUPPORT_SANITIZERS=ON -DPHOBOS_SYSTEM_ZLIB=ON
           - job_name: macOS 14, LLVM 17, latest LDC beta
             os: macos-14
             host_dc: ldc-beta
@@ -63,13 +63,13 @@ jobs:
             python3 -m pip install --user lit
           fi
           python3 -c "import lit.main; lit.main.main();" --version . | head -n 1
-      - name: 'Linux: Install gdb, llvm-symbolizer and libzstd'
+      - name: 'Linux: Install gdb, llvm-symbolizer, libzstd, zlib1g-dev'
         if: runner.os == 'Linux'
         run: |
           set -eux
           sudo apt-get update
           # Don't use latest gdb v10+ from Ubuntu toolchain PPA with regressions, use official v9
-          sudo apt-get install gdb=9.1-0ubuntu1 llvm libzstd-dev
+          sudo apt-get install gdb=9.1-0ubuntu1 llvm libzstd-dev zlib1g-dev
 
       - name: Try to restore cached LLVM
         uses: actions/cache@v4

CHANGELOG.md

@@ -5,6 +5,7 @@
 - LLVM for prebuilt packages bumped to v18.1.8 (incl. macOS arm64). (#4712)
 - Android: NDK for prebuilt package bumped from r26d to r27. (#4711)
 - ldc2.conf: %%ldcconfigpath%% placeholder added - specifies the directory where current configuration file is located. (#4717)
+- Add support for building against a system copy of zlib through `-DPHOBOS_SYSTEM_ZLIB=ON`. (#4742)
 
 #### Platform support
 
@@ -923,7 +924,7 @@
 - Misc. debuginfo issues, incl. adaptations to internal LLVM 5.0 changes: (#2315)
   - `ref` parameters and closure parameters declared with wrong address and hence potentially showing garbage.
   - Win64: parameters > 64 bit passed by value showing garbage.
-  - Win64: debuginfos for closure and nested variables now finally available starting with LLVM 5.0. 
+  - Win64: debuginfos for closure and nested variables now finally available starting with LLVM 5.0.
 - LLVM error `Global variable initializer type does not match global variable type!` for `T.init` with explicit initializers for dominated members in nested unions. (#2108)
 - Inconsistent handling of lvalue slicees wrt. visible side-effects of slice lower/upper bound expressions. (#1433)
 - Misc. dcompute issues. (#2195, #2215)

CMakeLists.txt

@@ -149,6 +149,9 @@ set(LDC_ENABLE_ASSERTIONS "${LLVM_ENABLE_ASSERTIONS}" CACHE BOOL "Enable LDC ass
 # Allow user to specify mimalloc.o location, to be linked with `ldc2` only
 set(ALTERNATIVE_MALLOC_O   ""     CACHE STRING "If specified, adds ALTERNATIVE_MALLOC_O object file to LDC link, to override the CRT malloc.")
 
+# Most linux distributions have a policy of not bundling dependencies like zlib
+set(PHOBOS_SYSTEM_ZLIB OFF CACHE BOOL "Use system zlib instead of Phobos' vendored version")
+
 if(D_VERSION EQUAL 1)
     message(FATAL_ERROR "D version 1 is no longer supported.
 Please consider using D version 2 or checkout the 'd1' git branch for the last version supporting D version 1.")
@@ -290,6 +293,9 @@ if(SANITIZE)
     endif()
 endif()
 append("${SANITIZE_CXXFLAGS}" LDC_CXXFLAGS)
+if(PHOBOS_SYSTEM_ZLIB)
+    append("-DPHOBOS_SYSTEM_ZLIB" LDC_CXXFLAGS)
+endif()
 # LLVM_CXXFLAGS may contain -Werror which causes compile errors with dmd source
 string(REPLACE "-Werror " "" LLVM_CXXFLAGS ${LLVM_CXXFLAGS})
 if (UNIX AND NOT "${LLVM_LDFLAGS}" STREQUAL "")

driver/linker-gcc.cpp

@@ -583,6 +583,10 @@ void ArgsBuilder::build(llvm::StringRef outputPath,
   for (const auto &name : defaultLibNames) {
     args.push_back("-l" + name);
   }
+#ifdef PHOBOS_SYSTEM_ZLIB
+  if (!defaultLibNames.empty() && !linkAgainstSharedDefaultLibs())
+      args.push_back("-lz");
+#endif
 
   // libs added via pragma(lib, libname)
   for (auto ls : global.params.linkswitches) {

runtime/CMakeLists.txt

@@ -61,6 +61,10 @@ if (RT_SUPPORT_SANITIZERS)
     list(APPEND D_FLAGS -d-version=SupportSanitizers)
 endif()
 
+if(PHOBOS_SYSTEM_ZLIB)
+    message(STATUS "-- Building PHOBOS against system zlib")
+endif()
+
 # Auto-detect TARGET_SYSTEM from host
 if("${TARGET_SYSTEM}" STREQUAL "AUTO")
     set(TARGET_SYSTEM ${CMAKE_SYSTEM_NAME})
@@ -243,14 +247,22 @@ if(PHOBOS2_DIR)
         list(REMOVE_ITEM PHOBOS2_D ${PHOBOS2_D_WINDOWS})
     endif()
 
-    # Phobos C parts
-    file(GLOB_RECURSE PHOBOS2_C ${PHOBOS2_DIR}/etc/*.c)
-    # remove zlib test modules
-    list(REMOVE_ITEM PHOBOS2_C
-        ${PHOBOS2_DIR}/etc/c/zlib/test/example.c
-        ${PHOBOS2_DIR}/etc/c/zlib/test/infcover.c
-        ${PHOBOS2_DIR}/etc/c/zlib/test/minigzip.c
-    )
+    if(PHOBOS_SYSTEM_ZLIB)
+	find_package(ZLIB REQUIRED)
+    else()
+	# Phobos C parts
+	file(GLOB_RECURSE PHOBOS2_C ${PHOBOS2_DIR}/etc/*.c)
+	# remove zlib test modules
+	list(REMOVE_ITEM PHOBOS2_C
+            ${PHOBOS2_DIR}/etc/c/zlib/test/example.c
+            ${PHOBOS2_DIR}/etc/c/zlib/test/infcover.c
+            ${PHOBOS2_DIR}/etc/c/zlib/test/minigzip.c
+	)
+	CHECK_INCLUDE_FILE(unistd.h HAVE_UNISTD_H)
+	if (HAVE_UNISTD_H)
+	    append("-DHAVE_UNISTD_H" CMAKE_C_FLAGS)
+	endif()
+    endif()
 endif()
 
 #
@@ -397,11 +409,6 @@ if("${TARGET_SYSTEM}" MATCHES "MSVC")
     # warning C4996: zlib uses 'deprecated' POSIX names
     append("/wd4100 /wd4127 /wd4131 /wd4206 /wd4244 /wd4245 /wd4267 /wd4996" CMAKE_C_FLAGS_RELEASE)
 endif()
-CHECK_INCLUDE_FILE(unistd.h HAVE_UNISTD_H)
-if (HAVE_UNISTD_H)
-    # Needed for zlib
-    append("-DHAVE_UNISTD_H" CMAKE_C_FLAGS)
-endif()
 # 2) Set all other CMAKE_C_FLAGS variants to CMAKE_C_FLAGS_RELEASE
 set(variables
     CMAKE_C_FLAGS_DEBUG
@@ -412,6 +419,16 @@ foreach(variable ${variables})
     set(${variable} "${CMAKE_C_FLAGS_RELEASE}")
 endforeach()
 
+function(link_zlib phobos_target library_type)
+    if(PHOBOS_SYSTEM_ZLIB)
+	if(${library_type} STREQUAL "SHARED")
+	    target_link_libraries(${phobos_target} ZLIB::ZLIB)
+	endif()
+    else()
+	target_sources(${phobos_target} PRIVATE ${PHOBOS2_C})
+    endif()
+endfunction()
+
 # Compiles the given D modules to object files, and if enabled, bitcode files.
 # The paths of the output files are appended to outlist_o and outlist_bc, respectively.
 macro(dc src_files src_basedir d_flags output_basedir emit_bc all_at_once single_obj_name outlist_o outlist_bc)
@@ -638,8 +655,8 @@ macro(build_runtime_libs druntime_o druntime_bc phobos2_o phobos2_bc c_flags ld_
     list(APPEND ${outlist_targets} druntime-ldc${target_suffix})
 
     if(PHOBOS2_DIR)
-        add_library(phobos2-ldc${target_suffix} ${library_type}
-            ${phobos2_o} ${PHOBOS2_C})
+        add_library(phobos2-ldc${target_suffix} ${library_type} ${phobos2_o})
+	link_zlib(phobos2-ldc${target_suffix} ${library_type})
         set_common_library_properties(phobos2-ldc${target_suffix}
             phobos2-ldc${lib_suffix} ${output_path}
             "${c_flags}" "${ld_flags}" ${is_shared}
@@ -669,8 +686,8 @@ macro(build_runtime_libs druntime_o druntime_bc phobos2_o phobos2_bc c_flags ld_
             "${c_flags}" "${ld_flags}" OFF
         )
 
-        add_library(phobos2-ldc-lto${target_suffix} STATIC
-            ${phobos2_bc} ${PHOBOS2_C})
+        add_library(phobos2-ldc-lto${target_suffix} STATIC ${phobos2_bc})
+	link_zlib(phobos2-ldc-lto${target_suffix} STATIC)
         set_common_library_properties(phobos2-ldc-lto${target_suffix}
             phobos2-ldc-lto${lib_suffix} ${output_path}
             "${c_flags}" "${ld_flags}" OFF
@@ -1004,6 +1021,9 @@ function(build_test_runners name_suffix path_suffix d_flags linkflags is_shared)
             LINK_FLAGS      ${linkflags}
             LINK_DEPENDS    ${tested_lib_path}
         )
+	if(PHOBOS_SYSTEM_ZLIB AND "${is_shared}" STREQUAL "OFF")
+	    target_link_libraries(${phobos_name} ZLIB::ZLIB)
+	endif()
         add_test(build-${phobos_name} "${CMAKE_COMMAND}" --build ${CMAKE_BINARY_DIR} --target ${phobos_name})
         set(_GLOBAL_TESTRUNNERS "${_GLOBAL_TESTRUNNERS};${phobos_name}" CACHE INTERNAL "")
     endif()

runtime/ldc-build-runtime.d.in

@@ -20,6 +20,7 @@ struct Config {
     string[] cFlags;
     string[] linkerFlags;
     uint numBuildJobs;
+    bool systemZlib;
     string[string] cmakeVars;
 }
 
@@ -160,6 +161,7 @@ void runCMake() {
     if (config.dFlags.length)       args ~= "-DD_EXTRA_FLAGS=" ~ config.dFlags.join(";");
     if (config.cFlags.length)       args ~= "-DRT_CFLAGS=" ~ config.cFlags.join(" ");
     if (config.linkerFlags.length)  args ~= "-DLD_FLAGS=" ~ config.linkerFlags.join(" ");
+    if (config.systemZlib)          args ~= "-DPHOBOS_SYSTEM_ZLIB=ON";
 
     foreach (pair; config.cmakeVars.byPair)
         args ~= "-D" ~ pair[0] ~ '=' ~ pair[1];
@@ -324,7 +326,8 @@ void parseCommandLine(string[] args) {
             "dFlags",      "Extra LDC flags for the D modules (separated by ';')", &config.dFlags,
             "cFlags",      "Extra C/ASM compiler flags for the handful of C/ASM files (separated by ';')", &config.cFlags,
             "linkerFlags", "Extra C linker flags for shared libraries and testrunner executables (separated by ';')", &config.linkerFlags,
-            "j",           "Number of parallel build jobs", &config.numBuildJobs
+            "j",           "Number of parallel build jobs", &config.numBuildJobs,
+            "systemZlib",  "Use system zlib instead of Phobos' vendored version", &config.systemZlib,
         );
 
         // getopt() has removed all consumed args from `args`