CMake: Improve usage of llvm-config (esp. for consistent static/shared linking)

CMakeLists.txt

@@ -66,9 +66,9 @@ endif()
 message(STATUS "Configuring zig version ${ZIG_VERSION}")
 
 set(ZIG_STATIC off CACHE BOOL "Attempt to build a static zig executable (not compatible with glibc)")
+set(ZIG_SHARED_LLVM off CACHE BOOL "Prefer linking against shared LLVM libraries")
 set(ZIG_STATIC_LLVM off CACHE BOOL "Prefer linking against static LLVM libraries")
 set(ZIG_STATIC_ZLIB off CACHE BOOL "Prefer linking against static zlib")
-set(ZIG_PREFER_CLANG_CPP_DYLIB off CACHE BOOL "Try to link against -lclang-cpp")
 set(ZIG_USE_CCACHE off CACHE BOOL "Use ccache if available")
 
 if(CCACHE_PROGRAM AND ZIG_USE_CCACHE)
@@ -80,6 +80,10 @@ if(ZIG_STATIC)
     set(ZIG_STATIC_ZLIB ON)
 endif()
 
+if (ZIG_SHARED_LLVM AND ZIG_STATIC_LLVM)
+    message(SEND_ERROR "-DZIG_SHARED_LLVM and -DZIG_STATIC_LLVM cannot both be enabled simultaneously")
+endif()
+
 string(REGEX REPLACE "\\\\" "\\\\\\\\" ZIG_LIBC_LIB_DIR_ESCAPED "${ZIG_LIBC_LIB_DIR}")
 string(REGEX REPLACE "\\\\" "\\\\\\\\" ZIG_LIBC_STATIC_LIB_DIR_ESCAPED "${ZIG_LIBC_STATIC_LIB_DIR}")
 string(REGEX REPLACE "\\\\" "\\\\\\\\" ZIG_LIBC_INCLUDE_DIR_ESCAPED "${ZIG_LIBC_INCLUDE_DIR}")

build.zig

@@ -660,6 +660,7 @@ fn addCMakeLibraryList(exe: *std.build.LibExeObjStep, list: []const u8) void {
 }
 
 const CMakeConfig = struct {
+    llvm_linkage: std.build.LibExeObjStep.Linkage,
     cmake_binary_dir: []const u8,
     cmake_prefix_path: []const u8,
     cxx_compiler: []const u8,
@@ -698,6 +699,7 @@ fn findAndParseConfigH(b: *Builder, config_h_path_option: ?[]const u8) ?CMakeCon
     };
 
     var ctx: CMakeConfig = .{
+        .llvm_linkage = undefined,
         .cmake_binary_dir = undefined,
         .cmake_prefix_path = undefined,
         .cxx_compiler = undefined,
@@ -741,6 +743,7 @@ fn findAndParseConfigH(b: *Builder, config_h_path_option: ?[]const u8) ?CMakeCon
             .prefix = "#define ZIG_DIA_GUIDS_LIB ",
             .field = "dia_guids_lib",
         },
+        // .prefix = ZIG_LLVM_LINK_MODE parsed manually below
     };
 
     var lines_it = mem.tokenize(u8, config_h_text, "\r\n");
@@ -753,6 +756,12 @@ fn findAndParseConfigH(b: *Builder, config_h_path_option: ?[]const u8) ?CMakeCon
                 @field(ctx, mapping.field) = toNativePathSep(b, quoted);
             }
         }
+        if (mem.startsWith(u8, line, "#define ZIG_LLVM_LINK_MODE ")) {
+            var it = mem.split(u8, line, "\"");
+            _ = it.next().?; // skip the stuff before the quote
+            const quoted = it.next().?; // the stuff inside the quote
+            ctx.llvm_linkage = if (mem.eql(u8, quoted, "shared")) .dynamic else .static;
+        }
     }
     return ctx;
 }

cmake/Findclang.cmake

@@ -8,52 +8,33 @@
 # CLANG_LIBDIRS
 
 find_path(CLANG_INCLUDE_DIRS NAMES clang/Frontend/ASTUnit.h
-  PATHS
-    /usr/lib/llvm/14/include
-    /usr/lib/llvm-14/include
-    /usr/lib/llvm-14.0/include
-    /usr/local/llvm140/include
-    /usr/local/llvm14/include
-    /usr/local/opt/llvm@14/include
-    /opt/homebrew/opt/llvm@14/include
-    /mingw64/include
+  HINTS ${LLVM_INCLUDE_DIRS}
+  # Only look for Clang next to LLVM or in { CMAKE_PREFIX_PATH, CMAKE_LIBRARY_PATH, CMAKE_FRAMEWORK_PATH }
+  NO_SYSTEM_ENVIRONMENT_PATH
+  NO_CMAKE_SYSTEM_PATH
 )
 
-if(ZIG_PREFER_CLANG_CPP_DYLIB)
+if(${LLVM_LINK_MODE} STREQUAL "shared")
   find_library(CLANG_LIBRARIES
     NAMES
+      libclang-cpp.so.14
       clang-cpp-14.0
       clang-cpp140
       clang-cpp
     NAMES_PER_DIR
-    PATHS
-      ${CLANG_LIBDIRS}
-      /usr/lib/llvm/14/lib
-      /usr/lib/llvm/14/lib64
-      /usr/lib/llvm-14/lib
-      /usr/local/llvm140/lib
-      /usr/local/llvm14/lib
-      /usr/local/opt/llvm@14/lib
-      /opt/homebrew/opt/llvm@14/lib
+    HINTS "${LLVM_LIBDIRS}"
+    # Only look for Clang next to LLVM or in { CMAKE_PREFIX_PATH, CMAKE_LIBRARY_PATH, CMAKE_FRAMEWORK_PATH }
+    NO_SYSTEM_ENVIRONMENT_PATH
+    NO_CMAKE_SYSTEM_PATH
   )
-endif()
-
-if(NOT CLANG_LIBRARIES)
+else()
   macro(FIND_AND_ADD_CLANG_LIB _libname_)
     string(TOUPPER ${_libname_} _prettylibname_)
     find_library(CLANG_${_prettylibname_}_LIB NAMES ${_libname_} NAMES_PER_DIR
-      PATHS
-        ${CLANG_LIBDIRS}
-        /usr/lib/llvm/14/lib
-        /usr/lib/llvm-14/lib
-        /usr/lib/llvm-14.0/lib
-        /usr/local/llvm140/lib
-        /usr/local/llvm14/lib
-        /usr/local/opt/llvm@14/lib
-        /opt/homebrew/opt/llvm@14/lib
-        /mingw64/lib
-        /c/msys64/mingw64/lib
-        c:\\msys64\\mingw64\\lib
+      HINTS "${LLVM_LIBDIRS}"
+      # Only look for Clang next to LLVM or in { CMAKE_PREFIX_PATH, CMAKE_LIBRARY_PATH, CMAKE_FRAMEWORK_PATH }
+      NO_SYSTEM_ENVIRONMENT_PATH
+      NO_CMAKE_SYSTEM_PATH
     )
     if(CLANG_${_prettylibname_}_LIB)
       set(CLANG_LIBRARIES ${CLANG_LIBRARIES} ${CLANG_${_prettylibname_}_LIB})

cmake/Findlld.cmake

@@ -7,6 +7,7 @@
 # LLD_LIBRARIES
 
 find_path(LLD_INCLUDE_DIRS NAMES lld/Common/Driver.h
+    HINTS ${LLVM_INCLUDE_DIRS}
     PATHS
         /usr/lib/llvm-14/include
         /usr/local/llvm140/include
@@ -16,6 +17,7 @@ find_path(LLD_INCLUDE_DIRS NAMES lld/Common/Driver.h
         /mingw64/include)
 
 find_library(LLD_LIBRARY NAMES lld-14.0 lld140 lld NAMES_PER_DIR
+    HINTS ${LLVM_LIBDIRS}
     PATHS
         /usr/lib/llvm-14/lib
         /usr/local/llvm140/lib
@@ -29,6 +31,7 @@ else()
     macro(FIND_AND_ADD_LLD_LIB _libname_)
         string(TOUPPER ${_libname_} _prettylibname_)
         find_library(LLD_${_prettylibname_}_LIB NAMES ${_libname_} NAMES_PER_DIR
+            HINTS ${LLVM_LIBDIRS}
             PATHS
                 ${LLD_LIBDIRS}
                 /usr/lib/llvm-14/lib
@@ -39,8 +42,8 @@ else()
                 /mingw64/lib
                 /c/msys64/mingw64/lib
                 c:/msys64/mingw64/lib)
-            if(LLD_${_prettylibname_}_LIB)
-                set(LLD_LIBRARIES ${LLD_LIBRARIES} ${LLD_${_prettylibname_}_LIB})
+        if(LLD_${_prettylibname_}_LIB)
+            set(LLD_LIBRARIES ${LLD_LIBRARIES} ${LLD_${_prettylibname_}_LIB})
         endif()
     endmacro(FIND_AND_ADD_LLD_LIB)