save generated app_data to an object file

crates/compiler/build/src/link.rs

@@ -1041,14 +1041,13 @@ fn link_macos(
             // "--gc-sections",
             "-arch",
             &arch,
-            // Suppress warnings, because otherwise it prints:
-            //
-            //   ld: warning: -undefined dynamic_lookup may not work with chained fixups
-            //
-            // We can't disable that option without breaking either x64 mac or ARM mac
-            "-w",
             "-macos_version_min",
             &get_macos_version(),
+            // Suppress fixup chains to ease working out dynamic relocs by the
+            // surgical linker. In my experience, working with dyld opcodes is
+            // slightly easier than unpacking compressed info from the __got section
+            // and fixups load command.
+            "-no_fixup_chains",
         ])
         .args(input_paths)
         .args(extra_link_flags());

crates/compiler/build/src/program.rs

@@ -949,6 +949,11 @@ fn build_loaded_file<'a>(
 
     match (linking_strategy, link_type) {
         (LinkingStrategy::Surgical, _) => {
+            if false {
+                let mut f = std::fs::File::create("tmp_roc.o").unwrap();
+                std::io::Write::write_all(&mut f, &roc_app_bytes).unwrap();
+            }
+
             let metadata_file = platform_main_roc_path.with_file_name(target.metadata_file_name());
 
             roc_linker::link_preprocessed_host(

crates/linker/src/generate_dylib/macho.rs

@@ -62,6 +62,7 @@ pub fn create_dylib_macho(
 
     let ld_flag_soname = "-install_name";
     let ld_prefix_args = [big_sur_fix, "-lSystem", "-dylib"];
+    let macos_version = get_macos_version();
 
     let output = Command::new("ld")
         .args(ld_prefix_args)
@@ -71,12 +72,15 @@ pub fn create_dylib_macho(
             dummy_obj_file.path().to_str().unwrap(),
             "-o",
             dummy_lib_file.to_str().unwrap(),
-            // Suppress warnings, because otherwise it prints:
-            //
-            //   ld: warning: -undefined dynamic_lookup may not work with chained fixups
-            //
-            // We can't disable that option without breaking either x64 mac or ARM mac
-            "-w",
+            // Suppress fixup chains to ease working out dynamic relocs by the
+            // surgical linker. In my experience, working with dyld opcodes is
+            // slightly easier than unpacking compressed info from the __got section
+            // and fixups load command.
+            "-no_fixup_chains",
+            "-platform_version",
+            "macos",
+            &macos_version,
+            &macos_version,
         ])
         .output()
         .unwrap();
@@ -98,3 +102,23 @@ pub fn create_dylib_macho(
 
     Ok(std::fs::read(dummy_lib_file).expect("Failed to load dummy library"))
 }
+
+fn get_macos_version() -> String {
+    let mut cmd = Command::new("sw_vers");
+    cmd.arg("-productVersion");
+
+    let cmd_stdout = cmd
+        .output()
+        .expect("Failed to execute command 'sw_vers -productVersion'")
+        .stdout;
+
+    let full_version_string = String::from_utf8(cmd_stdout)
+        .expect("Failed to convert output of command 'sw_vers -productVersion' into a utf8 string");
+
+    full_version_string
+        .trim_end()
+        .split('.')
+        .take(3)
+        .collect::<Vec<&str>>()
+        .join(".")
+}

crates/linker/src/lib.rs

@@ -35,6 +35,7 @@ pub fn supported(link_type: LinkType, target: Target) -> bool {
             Target::WinX64 => true,
             // macho support is incomplete
             Target::MacX64 => false,
+            Target::MacArm64 => true,
             _ => false,
         }
     } else {

crates/linker/src/macho.rs

@@ -1259,7 +1259,7 @@ fn surgery_macho_help(
             Some((_, size)) => size,
             None => 0,
         };
-        if sec.name().unwrap_or_default().starts_with("__BSS") {
+        if sec.name().unwrap_or_default().starts_with("__bss") {
             // bss sections only modify the virtual size.
             virt_offset += sec.size() as usize;
         } else if section_size != sec.size() {