Binding generation fails when generic struct is aliased #286
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Description
It looks like this happens when there is a generic struct in one module and a non-generic struct in another module, and you want to generate bindings for that non-generic struct. I have an example project here with these contents:
───────┬───────────────────────────────────────────────────────────────────
│ File: src/ffi.rs
───────┼───────────────────────────────────────────────────────────────────
1 │ type SomeType = super::MyStruct<u32>;
2 │
3 │ #[repr(C)]
4 │ pub struct MyStruct;
5 │
6 │ #[no_mangle]
7 │ pub extern "C" fn use_mystruct(my_struct: *mut MyStruct) {
8 │ }
───────┴───────────────────────────────────────────────────────────────────
───────┬───────────────────────────────────────────────────────────────────
│ File: src/lib.rs
───────┼───────────────────────────────────────────────────────────────────
1 │ pub mod ffi;
2 │
3 │ pub struct MyStruct<T> {
4 │ t: T,
5 │ }
───────┴───────────────────────────────────────────────────────────────────
───────┬───────────────────────────────────────────────────────────────────
│ File: build.rs
───────┼───────────────────────────────────────────────────────────────────
1 │ extern crate cbindgen;
2 │
3 │ use std::env;
4 │ use cbindgen::Language;
5 │
6 │ fn main() {
7 │ let crate_dir = env::var("CARGO_MANIFEST_DIR").unwrap();
8 │
9 │ cbindgen::Builder::new()
10 │ .with_crate(crate_dir)
11 │ .with_language(Language::C)
12 │ .generate()
13 │ .expect("Unable to generate bindings")
14 │ .write_to_file("bindings.h");
15 │ }
───────┴───────────────────────────────────────────────────────────────────
And I get this error:
allen@allen-XPS-13-9370 ~/s/cbindgen_bug> env RUST_BACKTRACE=1 cargo build
Compiling cbindgen_bug v0.1.0 (/home/allen/scratch/cbindgen_bug)
error: failed to run custom build command for `cbindgen_bug v0.1.0 (/home/allen/scratch/cbindgen_bug)`
process didn't exit successfully: `/home/allen/scratch/cbindgen_bug/target/debug/build/cbindgen_bug-34f7bb810f197ece/build-script-build` (exit code: 101)
--- stderr
thread 'main' panicked at 'MyStruct is not generic', /home/allen/.cargo/registry/src/github.com-1ecc6299db9ec823/cbindgen-0.7.1/src/bindgen/ir/structure.rs:290:9
stack backtrace:
0: std::sys::unix::backtrace::tracing::imp::unwind_backtrace
at src/libstd/sys/unix/backtrace/tracing/gcc_s.rs:49
1: std::sys_common::backtrace::_print
at src/libstd/sys_common/backtrace.rs:71
2: std::panicking::default_hook::{{closure}}
at src/libstd/sys_common/backtrace.rs:59
at src/libstd/panicking.rs:211
3: std::panicking::default_hook
at src/libstd/panicking.rs:227
4: std::panicking::rust_panic_with_hook
at src/libstd/panicking.rs:491
5: std::panicking::continue_panic_fmt
at src/libstd/panicking.rs:398
6: std::panicking::begin_panic_fmt
at src/libstd/panicking.rs:353
7: <cbindgen::bindgen::ir::structure::Struct as cbindgen::bindgen::ir::item::Item>::instantiate_monomorph
at /home/allen/.cargo/registry/src/github.com-1ecc6299db9ec823/cbindgen-0.7.1/src/bindgen/ir/structure.rs:290
8: cbindgen::bindgen::ir::ty::Type::add_monomorphs
at /home/allen/.cargo/registry/src/github.com-1ecc6299db9ec823/cbindgen-0.7.1/src/bindgen/ir/ty.rs:535
9: cbindgen::bindgen::ir::typedef::Typedef::add_monomorphs
at /home/allen/.cargo/registry/src/github.com-1ecc6299db9ec823/cbindgen-0.7.1/src/bindgen/ir/typedef.rs:108
10: cbindgen::bindgen::library::Library::instantiate_monomorphs::{{closure}}
at /home/allen/.cargo/registry/src/github.com-1ecc6299db9ec823/cbindgen-0.7.1/src/bindgen/library.rs:363
11: <cbindgen::bindgen::ir::item::ItemMap<T>>::for_all_items
at /home/allen/.cargo/registry/src/github.com-1ecc6299db9ec823/cbindgen-0.7.1/src/bindgen/ir/item.rs:188
12: cbindgen::bindgen::library::Library::instantiate_monomorphs
at /home/allen/.cargo/registry/src/github.com-1ecc6299db9ec823/cbindgen-0.7.1/src/bindgen/library.rs:362
13: cbindgen::bindgen::library::Library::generate
at /home/allen/.cargo/registry/src/github.com-1ecc6299db9ec823/cbindgen-0.7.1/src/bindgen/library.rs:63
14: cbindgen::bindgen::builder::Builder::generate
at /home/allen/.cargo/registry/src/github.com-1ecc6299db9ec823/cbindgen-0.7.1/src/bindgen/builder.rs:345
15: build_script_build::main
at ./build.rs:9
16: std::rt::lang_start::{{closure}}
at /rustc/9fda7c2237db910e41d6a712e9a2139b352e558b/src/libstd/rt.rs:74
17: std::panicking::try::do_call
at src/libstd/rt.rs:59
at src/libstd/panicking.rs:310
18: __rust_maybe_catch_panic
at src/libpanic_unwind/lib.rs:102
19: std::rt::lang_start_internal
at src/libstd/panicking.rs:289
at src/libstd/panic.rs:398
at src/libstd/rt.rs:58
20: std::rt::lang_start
at /rustc/9fda7c2237db910e41d6a712e9a2139b352e558b/src/libstd/rt.rs:74
21: main
22: __libc_start_main
23: _start
It's interesting that if I comment out line 1 of src/ffi.rs, then the bug doesn't occur and binding generation happens as I'd expect.
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