Generate extern wrappers for inlined functions

bindgen-cli/Cargo.toml

@@ -21,7 +21,7 @@ path = "main.rs"
 name = "bindgen"
 
 [dependencies]
-bindgen = { path = "../bindgen", version = "=0.63.0", features = ["cli"] }
+bindgen = { path = "../bindgen", version = "=0.63.0", features = ["cli", "experimental"] }
 shlex = "1"
 clap = { version = "4", features = ["derive"] }
 env_logger = { version = "0.9.0", optional = true }

bindgen-cli/options.rs

@@ -353,6 +353,21 @@ struct BindgenCommand {
     /// Derive custom traits on a `union`. The <CUSTOM> value must be of the shape <REGEX>=<DERIVE> where <DERIVE> is a coma-separated list of derive macros.
     #[arg(long, value_name = "CUSTOM")]
     with_derive_custom_union: Vec<String>,
+    /// Generate extern wrappers for inlined functions
+    #[arg(long, requires = "experimental")]
+    generate_extern_functions: bool,
+    /// Sets the name of the header and source code files that would be created if any extern wrapper functions must be generated due to the presence of inlined functions.
+    #[arg(long, requires = "experimental", value_name = "FILENAME")]
+    extern_functions_file_name: Option<String>,
+    #[arg(long, requires = "experimental", value_name = "DIRECTORY")]
+    /// Sets the directory path where any extra files must be created due to the presence of inlined functions.
+    extern_functions_directory: Option<String>,
+    /// Sets the suffix added to the extern wrapper functions generated for inlined functions.
+    #[arg(long, requires = "experimental", value_name = "SUFFIX")]
+    extern_function_suffix: Option<String>,
+    /// Enables experimental features.
+    #[arg(long)]
+    experimental: bool,
     /// Prints the version, and exits
     #[arg(short = 'V', long)]
     version: bool,
@@ -473,6 +488,11 @@ where
         with_derive_custom_struct,
         with_derive_custom_enum,
         with_derive_custom_union,
+        generate_extern_functions,
+        extern_functions_file_name,
+        extern_functions_directory,
+        extern_function_suffix,
+        experimental: _,
         version,
         clang_args,
     } = command;
@@ -978,5 +998,21 @@ where
         }
     }
 
+    if generate_extern_functions {
+        builder = builder.generate_extern_functions(true);
+    }
+
+    if let Some(file_name) = extern_functions_file_name {
+        builder = builder.extern_functions_file_name(file_name);
+    }
+
+    if let Some(directory) = extern_functions_directory {
+        builder = builder.extern_functions_directory(directory);
+    }
+
+    if let Some(suffix) = extern_function_suffix {
+        builder = builder.extern_function_suffix(suffix);
+    }
+
     Ok((builder, output, verbose))
 }

bindgen-integration/build.rs

@@ -4,7 +4,7 @@ extern crate cc;
 use bindgen::callbacks::{
     DeriveInfo, IntKind, MacroParsingBehavior, ParseCallbacks,
 };
-use bindgen::{Builder, EnumVariation};
+use bindgen::{Builder, CargoCallbacks, EnumVariation};
 use std::collections::HashSet;
 use std::env;
 use std::path::PathBuf;
@@ -28,21 +28,14 @@ impl ParseCallbacks for MacroCallback {
         MacroParsingBehavior::Default
     }
 
-    fn item_name(&self, original_item_name: &str) -> Option<String> {
-        if original_item_name.starts_with("my_prefixed_") {
-            Some(
-                original_item_name
-                    .trim_start_matches("my_prefixed_")
-                    .to_string(),
-            )
-        } else if original_item_name.starts_with("MY_PREFIXED_") {
-            Some(
-                original_item_name
-                    .trim_start_matches("MY_PREFIXED_")
-                    .to_string(),
-            )
-        } else {
-            None
+    fn int_macro(&self, name: &str, _value: i64) -> Option<IntKind> {
+        match name {
+            "TESTMACRO_CUSTOMINTKIND_PATH" => Some(IntKind::Custom {
+                name: "crate::MacroInteger",
+                is_signed: true,
+            }),
+
+            _ => None,
         }
     }
 
@@ -67,17 +60,6 @@ impl ParseCallbacks for MacroCallback {
         }
     }
 
-    fn int_macro(&self, name: &str, _value: i64) -> Option<IntKind> {
-        match name {
-            "TESTMACRO_CUSTOMINTKIND_PATH" => Some(IntKind::Custom {
-                name: "crate::MacroInteger",
-                is_signed: true,
-            }),
-
-            _ => None,
-        }
-    }
-
     fn func_macro(&self, name: &str, value: &[&[u8]]) {
         match name {
             "TESTMACRO_NONFUNCTIONAL" => {
@@ -122,6 +104,24 @@ impl ParseCallbacks for MacroCallback {
         }
     }
 
+    fn item_name(&self, original_item_name: &str) -> Option<String> {
+        if original_item_name.starts_with("my_prefixed_") {
+            Some(
+                original_item_name
+                    .trim_start_matches("my_prefixed_")
+                    .to_string(),
+            )
+        } else if original_item_name.starts_with("MY_PREFIXED_") {
+            Some(
+                original_item_name
+                    .trim_start_matches("MY_PREFIXED_")
+                    .to_string(),
+            )
+        } else {
+            None
+        }
+    }
+
     // Test the "custom derives" capability by adding `PartialEq` to the `Test` struct.
     fn add_derives(&self, info: &DeriveInfo<'_>) -> Vec<String> {
         if info.name == "Test" {
@@ -149,7 +149,7 @@ impl Drop for MacroCallback {
     }
 }
 
-fn main() {
+fn setup_macro_test() {
     cc::Build::new()
         .cpp(true)
         .file("cpp/Test.cc")
@@ -204,3 +204,71 @@ fn main() {
         "including stub via include dir must produce correct dep path",
     );
 }
+
+fn setup_extern_test() {
+    // GH-1090: https://github.com/rust-lang/rust-bindgen/issues/1090
+    // set output directory under /target so it is easy to clean generated files
+    let out_path = PathBuf::from(env::var("OUT_DIR").unwrap());
+    let out_rust_file = out_path.join("extern.rs");
+
+    let input_header_dir = PathBuf::from("../bindgen-tests/tests/headers/")
+        .canonicalize()
+        .expect("Cannot canonicalize libdir path");
+    let input_header_file_path =
+        input_header_dir.join("generate-extern-functions.h");
+    let input_header_file_path_str = input_header_file_path
+        .to_str()
+        .expect("Path could not be converted to a str");
+
+    // generate external bindings with the external .c and .h files
+    let bindings = Builder::default()
+        .header(input_header_file_path_str)
+        .parse_callbacks(Box::new(CargoCallbacks))
+        .generate_extern_functions(true)
+        .extern_functions_directory(out_path.display().to_string())
+        .generate()
+        .expect("Unable to generate bindings");
+
+    println!("cargo:rustc-link-lib=extern"); // tell cargo to link libextern
+    println!("bindings generated: {}", bindings);
+
+    let obj_path = out_path.join("extern.o");
+    let lib_path = out_path.join("libextern.a");
+
+    // build the external files to check if they work
+    if !std::process::Command::new("clang")
+        .arg("-c")
+        .arg("-o")
+        .arg(&obj_path)
+        .arg(out_path.join("extern.c"))
+        .arg("-include")
+        .arg(input_header_file_path)
+        .output()
+        .expect("`clang` command error")
+        .status
+        .success()
+    {
+        panic!("Could not compile object file");
+    }
+
+    if !std::process::Command::new("ar")
+        .arg("rcs")
+        .arg(lib_path)
+        .arg(obj_path)
+        .output()
+        .expect("`ar` command error")
+        .status
+        .success()
+    {
+        panic!("Could not emit library file");
+    }
+
+    bindings
+        .write_to_file(out_rust_file)
+        .expect("Cound not write bindings to the Rust file");
+}
+
+fn main() {
+    setup_macro_test();
+    setup_extern_test();
+}

bindgen-integration/src/lib.rs

@@ -4,6 +4,10 @@ mod bindings {
     include!(concat!(env!("OUT_DIR"), "/test.rs"));
 }
 
+mod extern_bindings {
+    include!(concat!(env!("OUT_DIR"), "/extern.rs"));
+}
+
 use std::ffi::CStr;
 use std::mem;
 use std::os::raw::c_int;
@@ -286,3 +290,15 @@ fn test_custom_derive() {
     assert!(meter < lightyear);
     assert!(meter > micron);
 }
+
+#[test]
+fn test_extern_bindings() {
+    // GH-1090: https://github.com/rust-lang/rust-bindgen/issues/1090
+    unsafe {
+        let f = extern_bindings::foo();
+        assert_eq!(11, f);
+
+        let b = extern_bindings::bar();
+        assert_eq!(1, b);
+    }
+}

bindgen-tests/Cargo.toml

@@ -5,7 +5,7 @@ version = "0.1.0"
 publish = false
 
 [dev-dependencies]
-bindgen = { path = "../bindgen", features = ["cli"] }
+bindgen = { path = "../bindgen", features = ["cli", "experimental"] }
 diff = "0.1"
 shlex = "1"
 clap = { version = "4", features = ["derive"] }

bindgen-tests/tests/expectations/tests/generated/README.md

@@ -0,0 +1,4 @@
+# Generated C, C++, Header files
+
+This directory contains files for features where extra files are generated
+as a part of the feature. For example, `--generated-extern-functions`.

bindgen-tests/tests/expectations/tests/generated/extern.c

@@ -0,0 +1,2 @@
+int foo__extern() { return foo(); }
+int bar__extern() { return bar(); }

bindgen-tests/tests/expectations/tests/generated/extern.h

@@ -0,0 +1,2 @@
+int foo__extern();
+int bar__extern();

bindgen-tests/tests/headers/generate-extern-functions.h

@@ -0,0 +1,11 @@
+// bindgen-flags: --experimental --generate-extern-functions
+
+static inline int foo() {
+    return 11;
+}
+static int bar() {
+    return 1;
+}
+inline int baz() {
+    return 2;
+}

bindgen-tests/tests/tests.rs

@@ -713,3 +713,52 @@ fn commandline_multiple_headers() {
         .header("tests/headers/16-byte-alignment.h");
     build_flags_output_helper(&bindings);
 }
+
+#[test]
+fn test_extern_generated_headers() {
+    // This test is for testing diffs of the generated C source and header files
+    // TODO: If another such feature is added, convert this test into a more generic
+    //      test that looks at `tests/headers/generated` directory.
+    let expect_path = PathBuf::from("tests/expectations/tests/generated");
+    println!("In path is ::: {}", expect_path.to_str().unwrap());
+
+    let generated_path = PathBuf::from(env::var("OUT_DIR").unwrap());
+    println!("Out path is ::: {}", generated_path.to_str().unwrap());
+
+    let _bindings = Builder::default()
+        .header("tests/headers/generate-extern-functions.h")
+        .generate_extern_functions(true)
+        .extern_functions_directory(generated_path.display().to_string())
+        .generate()
+        .expect("Failed to generate bindings");
+
+    let expected_c = fs::read_to_string(expect_path.join("extern.c"))
+        .expect("Could not read generated extern.c");
+    let expected_h = fs::read_to_string(expect_path.join("extern.h"))
+        .expect("Could not read generated extern.h");
+
+    let actual_c = fs::read_to_string(generated_path.join("extern.c"))
+        .expect("Could not read actual extern.c");
+    let actual_h = fs::read_to_string(generated_path.join("extern.h"))
+        .expect("Could not read actual extern.h");
+
+    if expected_c != actual_c {
+        error_diff_mismatch(
+            &actual_c,
+            &expected_c,
+            None,
+            Path::new(expect_path.join("extern.c").to_str().unwrap()),
+        )
+        .unwrap();
+    }
+
+    if expected_h != actual_h {
+        error_diff_mismatch(
+            &actual_h,
+            &expected_h,
+            None,
+            Path::new(expect_path.join("extern.h").to_str().unwrap()),
+        )
+        .unwrap();
+    }
+}

bindgen/Cargo.toml

@@ -48,6 +48,7 @@ runtime = ["clang-sys/runtime"]
 # Dynamically discover a `rustfmt` binary using the `which` crate
 which-rustfmt = ["which"]
 cli = []
+experimental = []
 
 # These features only exist for CI testing -- don't use them if you're not hacking
 # on bindgen!