also add static lib support with fallback to object file

crates/compiler/build/src/link.rs

@@ -54,14 +54,20 @@ pub fn link(
 }
 
 /// Same format as the precompiled host filename, except with a file extension like ".o" or ".obj"
-pub fn legacy_host_filename(target: &Triple) -> Option<String> {
+pub fn legacy_host_file(target: &Triple, platform_main_roc: &Path) -> Option<PathBuf> {
     let os = roc_target::OperatingSystem::from(target.operating_system);
-    let ext = os.object_file_ext();
+    let lib_ext = os.static_libary_file_ext();
 
-    Some(
-        roc_linker::preprocessed_host_filename(target)?
-            .replace(roc_linker::PRECOMPILED_HOST_EXT, ext),
-    )
+    let file_name = roc_linker::preprocessed_host_filename(target)?
+        .replace(roc_linker::PRECOMPILED_HOST_EXT, lib_ext);
+
+    let lib_path = platform_main_roc.with_file_name(file_name);
+    if lib_path.exists() {
+        Some(lib_path)
+    } else {
+        let obj_ext = os.object_file_ext();
+        Some(lib_path.with_extension(obj_ext))
+    }
 }
 
 // Attempts to find a file that is stored relative to the roc executable.
@@ -461,7 +467,7 @@ pub fn rebuild_host(
             .with_file_name("dynhost")
             .with_extension(executable_extension)
     } else {
-        platform_main_roc.with_file_name(legacy_host_filename(target).unwrap())
+        legacy_host_file(target, &platform_main_roc).unwrap()
     };
 
     let env_path = env::var("PATH").unwrap_or_else(|_| "".to_string());

crates/compiler/build/src/program.rs

@@ -1,5 +1,5 @@
 use crate::link::{
-    legacy_host_filename, link, preprocess_host_wasm32, rebuild_host, LinkType, LinkingStrategy,
+    legacy_host_file, link, preprocess_host_wasm32, rebuild_host, LinkType, LinkingStrategy,
 };
 use bumpalo::Bump;
 use inkwell::memory_buffer::MemoryBuffer;
@@ -828,8 +828,7 @@ fn build_loaded_file<'a>(
         // Fallback to legacy linking if the preprocessed host file does not exist, but a legacy host does exist.
         let preprocessed_host_path = platform_main_roc
             .with_file_name(roc_linker::preprocessed_host_filename(target).unwrap());
-        let legacy_host_path =
-            platform_main_roc.with_file_name(legacy_host_filename(target).unwrap());
+        let legacy_host_path = legacy_host_file(target, &platform_main_roc).unwrap();
         if !preprocessed_host_path.exists() && legacy_host_path.exists() {
             linking_strategy = LinkingStrategy::Legacy;
         }
@@ -842,7 +841,7 @@ fn build_loaded_file<'a>(
             // and has a file called "host.zig"
             platform_main_roc.with_file_name("host.zig")
         } else {
-            platform_main_roc.with_file_name(legacy_host_filename(target).unwrap())
+            legacy_host_file(target, &platform_main_roc).unwrap()
         }
     } else {
         platform_main_roc.with_file_name(roc_linker::preprocessed_host_filename(target).unwrap())

crates/compiler/roc_target/src/lib.rs

@@ -34,6 +34,14 @@ impl OperatingSystem {
         }
     }
 
+    pub const fn static_libary_file_ext(&self) -> &str {
+        match self {
+            OperatingSystem::Windows => "lib",
+            OperatingSystem::Unix => "a",
+            OperatingSystem::Wasi => "wasm",
+        }
+    }
+
     pub const fn executable_file_ext(&self) -> Option<&str> {
         match self {
             OperatingSystem::Windows => Some("exe"),