CMake: Add ZIG_LLVM_LINK_MODE to config.h

This is currently unused, but it will be needed soon so that we can
avoid linking static libc++ if LLVM/Clang is configured as a shared
library.

2 files changed, 10 insertions, 0 deletions

diff --git a/build.zig b/build.zig
index 31347f8e7e..220c9760f7 100644
--- a/build.zig
+++ b/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;
 }
diff --git a/src/stage1/config.h.in b/src/stage1/config.h.in
index 4d375652ff..2be0839996 100644
--- a/src/stage1/config.h.in
+++ b/src/stage1/config.h.in
@@ -16,6 +16,7 @@
 
 // Used by build.zig for communicating build information to self hosted build.
 #define ZIG_CMAKE_BINARY_DIR "@CMAKE_BINARY_DIR@"
+#define ZIG_LLVM_LINK_MODE "@LLVM_LINK_MODE@"
 #define ZIG_CMAKE_PREFIX_PATH "@CMAKE_PREFIX_PATH@"
 #define ZIG_CXX_COMPILER "@CMAKE_CXX_COMPILER@"
 #define ZIG_LLD_INCLUDE_PATH "@LLD_INCLUDE_DIRS@"