WIP: move abi checks to a feature and build the C code at build time

src/codegen/sys/build.rs

@@ -3,7 +3,7 @@ use crate::{codegen::general, env::Env, file_saver::save_to_file};
 use log::info;
 use std::io::{Result, Write};
 
-pub fn generate(env: &Env) {
+pub fn generate(env: &Env, has_abi_tests: bool) {
     info!(
         "Generating sys build script for {}",
         env.config.library_name
@@ -15,7 +15,7 @@ pub fn generate(env: &Env) {
     if !split_build_rs || !path.exists() {
         info!("Generating file {:?}", path);
         save_to_file(&path, env.config.make_backup, |w| {
-            generate_build_script(w, env, split_build_rs)
+            generate_build_script(w, env, split_build_rs, has_abi_tests)
         });
     }
 
@@ -29,11 +29,17 @@ pub fn generate(env: &Env) {
 }
 
 #[allow(clippy::write_literal)]
-fn generate_build_script(w: &mut dyn Write, env: &Env, split_build_rs: bool) -> Result<()> {
+fn generate_build_script(
+    w: &mut dyn Write,
+    env: &Env,
+    split_build_rs: bool,
+    has_abi_tests: bool,
+) -> Result<()> {
     if !split_build_rs {
         general::start_comments(w, &env.config)?;
         writeln!(w)?;
     }
+
     writeln!(
         w,
         "{}",
@@ -55,13 +61,42 @@ fn main() {} // prevent linking libraries to avoid documentation failure
 
 #[cfg(not(feature = "dox"))]
 fn main() {
-    if let Err(s) = system_deps::Config::new().probe() {
+    let deps = system_deps::Config::new().probe();
+    if let Err(s) = deps {
         println!("cargo:warning={}", s);
         process::exit(1);
+    }"##
+    )?;
+
+    if has_abi_tests {
+        write!(
+            w,
+            "{}",
+            r##"
+
+        #[cfg(feature = "abi-tests")]
+        {
+            let mut cc = cc::Build::new();
+
+            cc.flag_if_supported("-Wno-deprecated-declarations");
+            cc.flag_if_supported("-std=c11"); // for _Generic
+            cc.flag_if_supported("-std:c11"); // for _Generic (MSVC)
+
+            cc.file("tests/constant.c");
+            cc.file("tests/layout.c");
+
+            for i in deps.unwrap().all_include_paths() {
+                cc.include(i);
+            }
+
+            cc.compile("cabitests");
+        }
     }
-}
 "##
-    )
+        )
+    } else {
+        writeln!(w, "}}")
+    }
 }
 
 fn generate_build_version(w: &mut dyn Write, env: &Env) -> Result<()> {

src/codegen/sys/cargo_toml.rs

@@ -83,14 +83,13 @@ fn fill_in(root: &mut Table, env: &Env) {
 
     {
         let build_deps = upsert_table(root, "build-dependencies");
+        set_string(build_deps, "cc", "1.0");
         set_string(build_deps, "system-deps", "3");
     }
 
     {
         let dev_deps = upsert_table(root, "dev-dependencies");
         set_string(dev_deps, "shell-words", "1.0.0");
-        set_string(dev_deps, "tempfile", "3");
-        unset(dev_deps, "tempdir");
     }
 
     {
@@ -115,6 +114,7 @@ fn fill_in(root: &mut Table, env: &Env) {
                     .collect(),
             ),
         );
+        features.insert("abi-tests".to_string(), Value::Array(Vec::new()));
     }
 
     {

src/codegen/sys/mod.rs

@@ -13,9 +13,9 @@ 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);
+    let has_abi_tests = tests::generate(env, &crate_name);
+    build::generate(env, has_abi_tests);
 }
 
 pub fn collect_versions(env: &Env) -> BTreeMap<Version, Version> {