Merge pull request #2780 from rtfeldman/no-link

Add --no-link flag for more complex linking cases

Cargo.lock

@@ -3370,6 +3370,7 @@ dependencies = [
  "roc_can",
  "roc_collections",
  "roc_constrain",
+ "roc_error_macros",
  "roc_gen_dev",
  "roc_gen_llvm",
  "roc_gen_wasm",

cli/src/build.rs

@@ -246,6 +246,11 @@ pub fn build_file<'a>(
                 todo!("gracefully handle failing to surgically link");
             })?;
         BuildOutcome::NoProblems
+    } else if matches!(link_type, LinkType::None) {
+        // Just copy the object file to the output folder.
+        binary_path.set_extension(app_extension);
+        std::fs::copy(app_o_file, &binary_path).unwrap();
+        BuildOutcome::NoProblems
     } else {
         let mut inputs = vec![
             host_input_path.as_path().to_str().unwrap(),

cli/src/lib.rs

@@ -34,6 +34,7 @@ pub const FLAG_DEV: &str = "dev";
 pub const FLAG_OPTIMIZE: &str = "optimize";
 pub const FLAG_OPT_SIZE: &str = "opt-size";
 pub const FLAG_LIB: &str = "lib";
+pub const FLAG_NO_LINK: &str = "no-link";
 pub const FLAG_TARGET: &str = "target";
 pub const FLAG_TIME: &str = "time";
 pub const FLAG_LINK: &str = "roc-linker";
@@ -88,6 +89,12 @@ pub fn build_app<'a>() -> App<'a> {
                     .about("Build a C library instead of an executable.")
                     .required(false),
             )
+            .arg(
+                Arg::new(FLAG_NO_LINK)
+                    .long(FLAG_NO_LINK)
+                    .about("Does not link. Instead just outputs the `.o` file")
+                    .required(false),
+            )
             .arg(
                 Arg::new(FLAG_DEBUG)
                     .long(FLAG_DEBUG)
@@ -291,10 +298,14 @@ pub fn build(matches: &ArgMatches, config: BuildConfig) -> io::Result<i32> {
     let emit_debug_info = matches.is_present(FLAG_DEBUG);
     let emit_timings = matches.is_present(FLAG_TIME);
 
-    let link_type = if matches.is_present(FLAG_LIB) {
-        LinkType::Dylib
-    } else {
-        LinkType::Executable
+    let link_type = match (
+        matches.is_present(FLAG_LIB),
+        matches.is_present(FLAG_NO_LINK),
+    ) {
+        (true, false) => LinkType::Dylib,
+        (true, true) => user_error!("build can only be one of `--lib` or `--no-link`"),
+        (false, true) => LinkType::None,
+        (false, false) => LinkType::Executable,
     };
     let surgically_link = matches.is_present(FLAG_LINK);
     let precompiled = matches.is_present(FLAG_PRECOMPILED);

compiler/build/Cargo.toml

@@ -24,6 +24,7 @@ roc_gen_llvm = { path = "../gen_llvm", optional = true }
 roc_gen_wasm = { path = "../gen_wasm", optional = true }
 roc_gen_dev = { path = "../gen_dev", default-features = false }
 roc_reporting = { path = "../../reporting" }
+roc_error_macros = { path = "../../error_macros" }
 roc_std = { path = "../../roc_std", default-features = false }
 bumpalo = { version = "3.8.0", features = ["collections"] }
 libloading = "0.7.1"

compiler/build/src/link.rs

@@ -2,6 +2,7 @@ use crate::target::{arch_str, target_zig_str};
 #[cfg(feature = "llvm")]
 use libloading::{Error, Library};
 use roc_builtins::bitcode;
+use roc_error_macros::internal_error;
 // #[cfg(feature = "llvm")]
 use roc_mono::ir::OptLevel;
 use std::collections::HashMap;
@@ -20,10 +21,10 @@ fn zig_executable() -> String {
 
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
 pub enum LinkType {
-    // These numbers correspond to the --lib flag; if it's present
-    // (e.g. is_present returns `1 as bool`), this will be 1 as well.
+    // These numbers correspond to the --lib and --no-link flags
     Executable = 0,
     Dylib = 1,
+    None = 2,
 }
 
 /// input_paths can include the host as well as the app. e.g. &["host.o", "roc_app.o"]
@@ -835,6 +836,7 @@ fn link_linux(
                 output_path,
             )
         }
+        LinkType::None => internal_error!("link_linux should not be called with link type of none"),
     };
 
     let env_path = env::var("PATH").unwrap_or_else(|_| "".to_string());
@@ -904,6 +906,7 @@ fn link_macos(
 
             ("-dylib", output_path)
         }
+        LinkType::None => internal_error!("link_macos should not be called with link type of none"),
     };
 
     let arch = match target.architecture {