From c6d5e910a549b00047c48eb04113f0b068105857 Mon Sep 17 00:00:00 2001
From: Marco Mastropaolo <marcomp@amazon.com>
Date: Thu, 26 May 2022 18:17:57 +0200
Subject: [PATCH] Added self-linking support to sys mode

---
 book/src/config_ffi.md  | 7 +++++++
 src/codegen/sys/lib_.rs | 5 ++++-
 src/codegen/sys/mod.rs  | 9 ++++++---
 src/config/config.rs    | 7 +++++++
 4 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/book/src/config_ffi.md b/book/src/config_ffi.md
index e42c35d6b..22b77db32 100644
--- a/book/src/config_ffi.md
+++ b/book/src/config_ffi.md
@@ -35,6 +35,13 @@ work_mode = "sys"
 # and build.rs that generated only if not exists.
 # Defaults to false
 split_build_rs = false
+# If true, then build.rs and tests do not get generated, and
+# no #[link] attribute is emitted. This is supposed to be used
+# when a library consists of an hybrid of C and Rust code, and
+# the bindings to the C objects should be generated for Rust to
+# use.
+# Defaults to false
+self_linking = false
 # Adds extra versions to features
 extra_versions = [
    "3.15",
diff --git a/src/codegen/sys/lib_.rs b/src/codegen/sys/lib_.rs
index 4a0ebc482..b64f2b48b 100644
--- a/src/codegen/sys/lib_.rs
+++ b/src/codegen/sys/lib_.rs
@@ -71,7 +71,10 @@ fn generate_lib(w: &mut dyn Write, env: &Env) -> Result<()> {
     generate_classes_structs(w, env, &classes)?;
     generate_interfaces_structs(w, env, &interfaces)?;
 
-    write_link_attr(w, &env.namespaces.main().shared_libs)?;
+    if !env.config.self_linking {
+        write_link_attr(w, &env.namespaces.main().shared_libs)?;
+    }
+
     writeln!(w, "extern \"C\" {{")?;
     functions::generate_enums_funcs(w, env, &enums)?;
     functions::generate_bitfields_funcs(w, env, &bitfields)?;
diff --git a/src/codegen/sys/mod.rs b/src/codegen/sys/mod.rs
index fb7523e40..2bb36c080 100644
--- a/src/codegen/sys/mod.rs
+++ b/src/codegen/sys/mod.rs
@@ -13,9 +13,12 @@ mod tests;
 pub fn generate(env: &Env) {
     generate_single_version_file(env);
     lib_::generate(env);
-    build::generate(env);
-    let crate_name = cargo_toml::generate(env);
-    tests::generate(env, &crate_name);
+
+    if !env.config.self_linking {
+        build::generate(env);
+        let crate_name = cargo_toml::generate(env);
+        tests::generate(env, &crate_name);
+    }
 }
 
 pub fn collect_versions(env: &Env) -> BTreeMap<Version, Version> {
diff --git a/src/config/config.rs b/src/config/config.rs
index dbd8c34a3..7e9a2846d 100644
--- a/src/config/config.rs
+++ b/src/config/config.rs
@@ -115,6 +115,7 @@ pub struct Config {
     pub docs_rs_features: Vec<String>,
     pub disable_format: bool,
     pub split_build_rs: bool,
+    pub self_linking: bool,
     pub extra_versions: Vec<Version>,
     pub lib_version_overrides: HashMap<Version, Version>,
     pub feature_dependencies: HashMap<Version, Vec<String>>,
@@ -341,6 +342,11 @@ impl Config {
             None => false,
         };
 
+        let self_linking = match toml.lookup("options.self_linking") {
+            Some(v) => v.as_result_bool("options.self_linking")?,
+            None => false,
+        };
+
         let extra_versions = read_extra_versions(&toml)?;
         let lib_version_overrides = read_lib_version_overrides(&toml)?;
         let feature_dependencies = read_feature_dependencies(&toml)?;
@@ -369,6 +375,7 @@ impl Config {
             docs_rs_features,
             disable_format,
             split_build_rs,
+            self_linking,
             extra_versions,
             lib_version_overrides,
             feature_dependencies,