1 //! Printing logic for basic blocks of Rust-mapped code - parts of functions and declarations but
2 //! not the full mapping logic.
6 use proc_macro2::{TokenTree, Span};
10 /// Writes out a C++ wrapper class for the given type, which contains various utilities to access
11 /// the underlying C-mapped type safely avoiding some common memory management issues by handling
12 /// resource-freeing and prevending accidental raw copies.
13 pub fn write_cpp_wrapper(cpp_header_file: &mut File, ty: &str, has_destructor: bool) {
14 writeln!(cpp_header_file, "class {} {{", ty).unwrap();
15 writeln!(cpp_header_file, "private:").unwrap();
16 writeln!(cpp_header_file, "\tLDK{} self;", ty).unwrap();
17 writeln!(cpp_header_file, "public:").unwrap();
18 writeln!(cpp_header_file, "\t{}(const {}&) = delete;", ty, ty).unwrap();
19 writeln!(cpp_header_file, "\t{}({}&& o) : self(o.self) {{ memset(&o, 0, sizeof({})); }}", ty, ty, ty).unwrap();
20 writeln!(cpp_header_file, "\t{}(LDK{}&& m_self) : self(m_self) {{ memset(&m_self, 0, sizeof(LDK{})); }}", ty, ty, ty).unwrap();
21 writeln!(cpp_header_file, "\toperator LDK{}() && {{ LDK{} res = self; memset(&self, 0, sizeof(LDK{})); return res; }}", ty, ty, ty).unwrap();
23 writeln!(cpp_header_file, "\t~{}() {{ {}_free(self); }}", ty, ty).unwrap();
24 writeln!(cpp_header_file, "\t{}& operator=({}&& o) {{ {}_free(self); self = o.self; memset(&o, 0, sizeof({})); return *this; }}", ty, ty, ty, ty).unwrap();
26 writeln!(cpp_header_file, "\t{}& operator=({}&& o) {{ self = o.self; memset(&o, 0, sizeof({})); return *this; }}", ty, ty, ty).unwrap();
28 writeln!(cpp_header_file, "\tLDK{}* operator &() {{ return &self; }}", ty).unwrap();
29 writeln!(cpp_header_file, "\tLDK{}* operator ->() {{ return &self; }}", ty).unwrap();
30 writeln!(cpp_header_file, "\tconst LDK{}* operator &() const {{ return &self; }}", ty).unwrap();
31 writeln!(cpp_header_file, "\tconst LDK{}* operator ->() const {{ return &self; }}", ty).unwrap();
32 writeln!(cpp_header_file, "}};").unwrap();
35 /// Writes out a C-callable concrete Result<A, B> struct and utility methods
36 pub fn write_result_block<W: std::io::Write>(w: &mut W, mangled_container: &str, ok_type: &str, err_type: &str, clonable: bool) {
37 writeln!(w, "#[repr(C)]").unwrap();
38 writeln!(w, "pub union {}Ptr {{", mangled_container).unwrap();
40 writeln!(w, "\tpub result: *mut {},", ok_type).unwrap();
42 writeln!(w, "\t/// Note that this value is always NULL, as there are no contents in the OK variant").unwrap();
43 writeln!(w, "\tpub result: *mut std::ffi::c_void,").unwrap();
46 writeln!(w, "\tpub err: *mut {},", err_type).unwrap();
48 writeln!(w, "\t/// Note that this value is always NULL, as there are no contents in the Err variant").unwrap();
49 writeln!(w, "\tpub err: *mut std::ffi::c_void,").unwrap();
51 writeln!(w, "}}").unwrap();
52 writeln!(w, "#[repr(C)]").unwrap();
53 writeln!(w, "pub struct {} {{", mangled_container).unwrap();
54 writeln!(w, "\tpub contents: {}Ptr,", mangled_container).unwrap();
55 writeln!(w, "\tpub result_ok: bool,").unwrap();
56 writeln!(w, "}}").unwrap();
58 writeln!(w, "#[no_mangle]").unwrap();
60 writeln!(w, "pub extern \"C\" fn {}_ok(o: {}) -> {} {{", mangled_container, ok_type, mangled_container).unwrap();
62 writeln!(w, "pub extern \"C\" fn {}_ok() -> {} {{", mangled_container, mangled_container).unwrap();
64 writeln!(w, "\t{} {{", mangled_container).unwrap();
65 writeln!(w, "\t\tcontents: {}Ptr {{", mangled_container).unwrap();
67 writeln!(w, "\t\t\tresult: Box::into_raw(Box::new(o)),").unwrap();
69 writeln!(w, "\t\t\tresult: std::ptr::null_mut(),").unwrap();
71 writeln!(w, "\t\t}},").unwrap();
72 writeln!(w, "\t\tresult_ok: true,").unwrap();
73 writeln!(w, "\t}}").unwrap();
74 writeln!(w, "}}").unwrap();
76 writeln!(w, "#[no_mangle]").unwrap();
78 writeln!(w, "pub extern \"C\" fn {}_err(e: {}) -> {} {{", mangled_container, err_type, mangled_container).unwrap();
80 writeln!(w, "pub extern \"C\" fn {}_err() -> {} {{", mangled_container, mangled_container).unwrap();
82 writeln!(w, "\t{} {{", mangled_container).unwrap();
83 writeln!(w, "\t\tcontents: {}Ptr {{", mangled_container).unwrap();
85 writeln!(w, "\t\t\terr: Box::into_raw(Box::new(e)),").unwrap();
87 writeln!(w, "\t\t\terr: std::ptr::null_mut(),").unwrap();
89 writeln!(w, "\t\t}},").unwrap();
90 writeln!(w, "\t\tresult_ok: false,").unwrap();
91 writeln!(w, "\t}}").unwrap();
92 writeln!(w, "}}").unwrap();
94 writeln!(w, "#[no_mangle]").unwrap();
95 writeln!(w, "pub extern \"C\" fn {}_free(_res: {}) {{ }}", mangled_container, mangled_container).unwrap();
96 writeln!(w, "impl Drop for {} {{", mangled_container).unwrap();
97 writeln!(w, "\tfn drop(&mut self) {{").unwrap();
98 writeln!(w, "\t\tif self.result_ok {{").unwrap();
100 writeln!(w, "\t\t\tif unsafe {{ !(self.contents.result as *mut ()).is_null() }} {{").unwrap();
101 writeln!(w, "\t\t\t\tlet _ = unsafe {{ Box::from_raw(self.contents.result) }};").unwrap();
102 writeln!(w, "\t\t\t}}").unwrap();
104 writeln!(w, "\t\t}} else {{").unwrap();
105 if err_type != "()" {
106 writeln!(w, "\t\t\tif unsafe {{ !(self.contents.err as *mut ()).is_null() }} {{").unwrap();
107 writeln!(w, "\t\t\t\tlet _ = unsafe {{ Box::from_raw(self.contents.err) }};").unwrap();
108 writeln!(w, "\t\t\t}}").unwrap();
110 writeln!(w, "\t\t}}").unwrap();
111 writeln!(w, "\t}}").unwrap();
112 writeln!(w, "}}").unwrap();
114 // TODO: Templates should use () now that they can, too
115 let templ_ok_type = if ok_type != "()" { ok_type } else { "u8" };
116 let templ_err_type = if err_type != "()" { err_type } else { "u8" };
118 writeln!(w, "impl From<crate::c_types::CResultTempl<{}, {}>> for {} {{", templ_ok_type, templ_err_type, mangled_container).unwrap();
119 writeln!(w, "\tfn from(mut o: crate::c_types::CResultTempl<{}, {}>) -> Self {{", templ_ok_type, templ_err_type).unwrap();
120 writeln!(w, "\t\tlet contents = if o.result_ok {{").unwrap();
122 writeln!(w, "\t\t\tlet result = unsafe {{ o.contents.result }};").unwrap();
123 writeln!(w, "\t\t\tunsafe {{ o.contents.result = std::ptr::null_mut() }};").unwrap();
124 writeln!(w, "\t\t\t{}Ptr {{ result }}", mangled_container).unwrap();
126 writeln!(w, "\t\t\tlet _ = unsafe {{ Box::from_raw(o.contents.result) }};").unwrap();
127 writeln!(w, "\t\t\to.contents.result = std::ptr::null_mut();").unwrap();
128 writeln!(w, "\t\t\t{}Ptr {{ result: std::ptr::null_mut() }}", mangled_container).unwrap();
130 writeln!(w, "\t\t}} else {{").unwrap();
131 if err_type != "()" {
132 writeln!(w, "\t\t\tlet err = unsafe {{ o.contents.err }};").unwrap();
133 writeln!(w, "\t\t\tunsafe {{ o.contents.err = std::ptr::null_mut(); }}").unwrap();
134 writeln!(w, "\t\t\t{}Ptr {{ err }}", mangled_container).unwrap();
136 writeln!(w, "\t\t\tlet _ = unsafe {{ Box::from_raw(o.contents.err) }};").unwrap();
137 writeln!(w, "\t\t\to.contents.err = std::ptr::null_mut();").unwrap();
138 writeln!(w, "\t\t\t{}Ptr {{ err: std::ptr::null_mut() }}", mangled_container).unwrap();
140 writeln!(w, "\t\t}};").unwrap();
141 writeln!(w, "\t\tSelf {{").unwrap();
142 writeln!(w, "\t\t\tcontents,").unwrap();
143 writeln!(w, "\t\t\tresult_ok: o.result_ok,").unwrap();
144 writeln!(w, "\t\t}}").unwrap();
145 writeln!(w, "\t}}").unwrap();
146 writeln!(w, "}}").unwrap();
149 writeln!(w, "impl Clone for {} {{", mangled_container).unwrap();
150 writeln!(w, "\tfn clone(&self) -> Self {{").unwrap();
151 writeln!(w, "\t\tif self.result_ok {{").unwrap();
152 writeln!(w, "\t\t\tSelf {{ result_ok: true, contents: {}Ptr {{", mangled_container).unwrap();
154 writeln!(w, "\t\t\t\tresult: Box::into_raw(Box::new(<{}>::clone(unsafe {{ &*self.contents.result }})))", ok_type).unwrap();
156 writeln!(w, "\t\t\t\tresult: std::ptr::null_mut()").unwrap();
158 writeln!(w, "\t\t\t}} }}").unwrap();
159 writeln!(w, "\t\t}} else {{").unwrap();
160 writeln!(w, "\t\t\tSelf {{ result_ok: false, contents: {}Ptr {{", mangled_container).unwrap();
161 if err_type != "()" {
162 writeln!(w, "\t\t\t\terr: Box::into_raw(Box::new(<{}>::clone(unsafe {{ &*self.contents.err }})))", err_type).unwrap();
164 writeln!(w, "\t\t\t\terr: std::ptr::null_mut()").unwrap();
166 writeln!(w, "\t\t\t}} }}").unwrap();
167 writeln!(w, "\t\t}}").unwrap();
168 writeln!(w, "\t}}").unwrap();
169 writeln!(w, "}}").unwrap();
170 writeln!(w, "#[no_mangle]").unwrap();
171 writeln!(w, "pub extern \"C\" fn {}_clone(orig: &{}) -> {} {{ orig.clone() }}", mangled_container, mangled_container, mangled_container).unwrap();
175 /// Writes out a C-callable concrete Vec<A> struct and utility methods
176 pub fn write_vec_block<W: std::io::Write>(w: &mut W, mangled_container: &str, inner_type: &str, clonable: bool) {
177 writeln!(w, "#[repr(C)]").unwrap();
178 writeln!(w, "pub struct {} {{", mangled_container).unwrap();
179 writeln!(w, "\tpub data: *mut {},", inner_type).unwrap();
180 writeln!(w, "\tpub datalen: usize").unwrap();
181 writeln!(w, "}}").unwrap();
183 writeln!(w, "impl {} {{", mangled_container).unwrap();
184 writeln!(w, "\t#[allow(unused)] pub(crate) fn into_rust(&mut self) -> Vec<{}> {{", inner_type).unwrap();
185 writeln!(w, "\t\tif self.datalen == 0 {{ return Vec::new(); }}").unwrap();
186 writeln!(w, "\t\tlet ret = unsafe {{ Box::from_raw(std::slice::from_raw_parts_mut(self.data, self.datalen)) }}.into();").unwrap();
187 writeln!(w, "\t\tself.data = std::ptr::null_mut();").unwrap();
188 writeln!(w, "\t\tself.datalen = 0;").unwrap();
189 writeln!(w, "\t\tret").unwrap();
190 writeln!(w, "\t}}").unwrap();
191 writeln!(w, "\t#[allow(unused)] pub(crate) fn as_slice(&self) -> &[{}] {{", inner_type).unwrap();
192 writeln!(w, "\t\tunsafe {{ std::slice::from_raw_parts_mut(self.data, self.datalen) }}").unwrap();
193 writeln!(w, "\t}}").unwrap();
194 writeln!(w, "}}").unwrap();
196 writeln!(w, "impl From<Vec<{}>> for {} {{", inner_type, mangled_container).unwrap();
197 writeln!(w, "\tfn from(v: Vec<{}>) -> Self {{", inner_type).unwrap();
198 writeln!(w, "\t\tlet datalen = v.len();").unwrap();
199 writeln!(w, "\t\tlet data = Box::into_raw(v.into_boxed_slice());").unwrap();
200 writeln!(w, "\t\tSelf {{ datalen, data: unsafe {{ (*data).as_mut_ptr() }} }}").unwrap();
201 writeln!(w, "\t}}").unwrap();
202 writeln!(w, "}}").unwrap();
204 writeln!(w, "#[no_mangle]").unwrap();
205 writeln!(w, "pub extern \"C\" fn {}_free(_res: {}) {{ }}", mangled_container, mangled_container).unwrap();
206 writeln!(w, "impl Drop for {} {{", mangled_container).unwrap();
207 writeln!(w, "\tfn drop(&mut self) {{").unwrap();
208 writeln!(w, "\t\tif self.datalen == 0 {{ return; }}").unwrap();
209 writeln!(w, "\t\tunsafe {{ Box::from_raw(std::slice::from_raw_parts_mut(self.data, self.datalen)) }};").unwrap();
210 writeln!(w, "\t}}").unwrap();
211 writeln!(w, "}}").unwrap();
213 writeln!(w, "impl Clone for {} {{", mangled_container).unwrap();
214 writeln!(w, "\tfn clone(&self) -> Self {{").unwrap();
215 writeln!(w, "\t\tlet mut res = Vec::new();").unwrap();
216 writeln!(w, "\t\tif self.datalen == 0 {{ return Self::from(res); }}").unwrap();
217 writeln!(w, "\t\tres.extend_from_slice(unsafe {{ std::slice::from_raw_parts_mut(self.data, self.datalen) }});").unwrap();
218 writeln!(w, "\t\tSelf::from(res)").unwrap();
219 writeln!(w, "\t}}").unwrap();
220 writeln!(w, "}}").unwrap();
224 /// Prints the docs from a given attribute list unless its tagged no export
225 pub fn writeln_docs<W: std::io::Write>(w: &mut W, attrs: &[syn::Attribute], prefix: &str) {
226 for attr in attrs.iter() {
227 let tokens_clone = attr.tokens.clone();
228 let mut token_iter = tokens_clone.into_iter();
229 if let Some(token) = token_iter.next() {
231 TokenTree::Punct(c) if c.as_char() == '=' => {
232 // syn gets '=' from '///' or '//!' as it is syntax for #[doc = ""]
234 TokenTree::Group(_) => continue, // eg #[derive()]
235 _ => unimplemented!(),
239 syn::AttrStyle::Inner(_) => {
240 match token_iter.next().unwrap() {
241 TokenTree::Literal(lit) => {
242 // Drop the first and last chars from lit as they are always "
243 let doc = format!("{}", lit);
244 writeln!(w, "{}//!{}", prefix, &doc[1..doc.len() - 1]).unwrap();
246 _ => unimplemented!(),
249 syn::AttrStyle::Outer => {
250 match token_iter.next().unwrap() {
251 TokenTree::Literal(lit) => {
252 // Drop the first and last chars from lit as they are always "
253 let doc = format!("{}", lit);
254 writeln!(w, "{}///{}", prefix, &doc[1..doc.len() - 1]).unwrap();
256 _ => unimplemented!(),
263 /// Print the parameters in a method declaration, starting after the open parenthesis, through and
264 /// including the closing parenthesis and return value, but not including the open bracket or any
265 /// trailing semicolons.
267 /// Usable both for a function definition and declaration.
269 /// this_param is used when returning Self or accepting a self parameter, and should be the
270 /// concrete, mapped type.
271 pub fn write_method_params<W: std::io::Write>(w: &mut W, sig: &syn::Signature, this_param: &str, types: &mut TypeResolver, generics: Option<&GenericTypes>, self_ptr: bool, fn_decl: bool) {
272 if sig.constness.is_some() || sig.asyncness.is_some() || sig.unsafety.is_some() ||
273 sig.abi.is_some() || sig.variadic.is_some() {
276 if sig.generics.lt_token.is_some() {
277 for generic in sig.generics.params.iter() {
279 syn::GenericParam::Type(_)|syn::GenericParam::Lifetime(_) => {
280 // We ignore these, if they're not on skipped args, we'll blow up
281 // later, and lifetimes we just hope the C client enforces.
283 _ => unimplemented!(),
288 let mut first_arg = true;
289 let mut num_unused = 0;
290 for inp in sig.inputs.iter() {
292 syn::FnArg::Receiver(recv) => {
293 if !recv.attrs.is_empty() || recv.reference.is_none() { unimplemented!(); }
294 write!(w, "this_arg: {}{}",
295 match (self_ptr, recv.mutability.is_some()) {
296 (true, true) => "*mut ",
297 (true, false) => "*const ",
298 (false, true) => "&mut ",
299 (false, false) => "&",
300 }, this_param).unwrap();
304 syn::FnArg::Typed(arg) => {
305 if types.skip_arg(&*arg.ty, generics) { continue; }
306 if !arg.attrs.is_empty() { unimplemented!(); }
307 // First get the c type so that we can check if it ends up being a reference:
308 let mut c_type = Vec::new();
309 types.write_c_type(&mut c_type, &*arg.ty, generics, false);
311 syn::Pat::Ident(ident) => {
312 if !ident.attrs.is_empty() || ident.subpat.is_some() {
315 write!(w, "{}{}{}: ", if first_arg { "" } else { ", " }, if !fn_decl || c_type[0] == '&' as u8 || c_type[0] == '*' as u8 { "" } else { "mut " }, ident.ident).unwrap();
318 syn::Pat::Wild(wild) => {
319 if !wild.attrs.is_empty() { unimplemented!(); }
320 write!(w, "{}unused_{}: ", if first_arg { "" } else { ", " }, num_unused).unwrap();
323 _ => unimplemented!(),
325 w.write(&c_type).unwrap();
329 write!(w, ")").unwrap();
331 syn::ReturnType::Type(_, rtype) => {
332 write!(w, " -> ").unwrap();
333 if let Some(mut remaining_path) = first_seg_self(&*rtype) {
334 if remaining_path.next().is_none() {
335 write!(w, "{}", this_param).unwrap();
339 if let syn::Type::Reference(r) = &**rtype {
340 // We can't return a reference, cause we allocate things on the stack.
341 types.write_c_type(w, &*r.elem, generics, true);
343 types.write_c_type(w, &*rtype, generics, true);
350 /// Print the main part of a method declaration body, starting with a newline after the function
351 /// open bracket and converting each function parameter to or from C-mapped types. Ends with "let
352 /// mut ret = " assuming the next print will be the unmapped Rust function to call followed by the
353 /// parameters we mapped to/from C here.
354 pub fn write_method_var_decl_body<W: std::io::Write>(w: &mut W, sig: &syn::Signature, extra_indent: &str, types: &TypeResolver, generics: Option<&GenericTypes>, to_c: bool) {
355 let mut num_unused = 0;
356 for inp in sig.inputs.iter() {
358 syn::FnArg::Receiver(_) => {},
359 syn::FnArg::Typed(arg) => {
360 if types.skip_arg(&*arg.ty, generics) { continue; }
361 if !arg.attrs.is_empty() { unimplemented!(); }
362 macro_rules! write_new_var {
363 ($ident: expr, $ty: expr) => {
365 if types.write_to_c_conversion_new_var(w, &$ident, &$ty, generics, false) {
366 write!(w, "\n\t{}", extra_indent).unwrap();
369 if types.write_from_c_conversion_new_var(w, &$ident, &$ty, generics) {
370 write!(w, "\n\t{}", extra_indent).unwrap();
376 syn::Pat::Ident(ident) => {
377 if !ident.attrs.is_empty() || ident.subpat.is_some() {
380 write_new_var!(ident.ident, *arg.ty);
382 syn::Pat::Wild(w) => {
383 if !w.attrs.is_empty() { unimplemented!(); }
384 write_new_var!(syn::Ident::new(&format!("unused_{}", num_unused), Span::call_site()), *arg.ty);
387 _ => unimplemented!(),
393 syn::ReturnType::Type(_, _) => {
394 write!(w, "let mut ret = ").unwrap();
400 /// Prints the parameters in a method call, starting after the open parenthesis and ending with a
401 /// final return statement returning the method's result. Should be followed by a single closing
404 /// The return value is expected to be bound to a variable named `ret` which is available after a
405 /// method-call-ending semicolon.
406 pub fn write_method_call_params<W: std::io::Write>(w: &mut W, sig: &syn::Signature, extra_indent: &str, types: &TypeResolver, generics: Option<&GenericTypes>, this_type: &str, to_c: bool) {
407 let mut first_arg = true;
408 let mut num_unused = 0;
409 for inp in sig.inputs.iter() {
411 syn::FnArg::Receiver(recv) => {
412 if !recv.attrs.is_empty() || recv.reference.is_none() { unimplemented!(); }
414 write!(w, "self.this_arg").unwrap();
418 syn::FnArg::Typed(arg) => {
419 if types.skip_arg(&*arg.ty, generics) {
422 write!(w, ", ").unwrap();
425 types.no_arg_to_rust(w, &*arg.ty, generics);
429 if !arg.attrs.is_empty() { unimplemented!(); }
430 macro_rules! write_ident {
433 write!(w, ", ").unwrap();
437 types.write_to_c_conversion_inline_prefix(w, &*arg.ty, generics, false);
438 write!(w, "{}", $ident).unwrap();
439 types.write_to_c_conversion_inline_suffix(w, &*arg.ty, generics, false);
441 types.write_from_c_conversion_prefix(w, &*arg.ty, generics);
442 write!(w, "{}", $ident).unwrap();
443 types.write_from_c_conversion_suffix(w, &*arg.ty, generics);
448 syn::Pat::Ident(ident) => {
449 if !ident.attrs.is_empty() || ident.subpat.is_some() {
452 write_ident!(ident.ident);
454 syn::Pat::Wild(w) => {
455 if !w.attrs.is_empty() { unimplemented!(); }
456 write_ident!(format!("unused_{}", num_unused));
459 _ => unimplemented!(),
464 write!(w, ")").unwrap();
466 syn::ReturnType::Type(_, rtype) => {
467 write!(w, ";\n\t{}", extra_indent).unwrap();
469 let self_segs_iter = first_seg_self(&*rtype);
470 if to_c && first_seg_self(&*rtype).is_some() {
471 // Assume rather blindly that we're returning an associated trait from a C fn call to a Rust trait object.
472 write!(w, "ret").unwrap();
473 } else if !to_c && self_segs_iter.is_some() && self_segs_iter.unwrap().next().is_none() {
474 // If we're returning "Self" (and not "Self::X"), just do it manually
475 write!(w, "{} {{ inner: Box::into_raw(Box::new(ret)), is_owned: true }}", this_type).unwrap();
477 let new_var = types.write_from_c_conversion_new_var(w, &syn::Ident::new("ret", Span::call_site()), rtype, generics);
479 write!(w, "\n\t{}", extra_indent).unwrap();
481 types.write_from_c_conversion_prefix(w, &*rtype, generics);
482 write!(w, "ret").unwrap();
483 types.write_from_c_conversion_suffix(w, &*rtype, generics);
485 let ret_returned = if let syn::Type::Reference(_) = &**rtype { true } else { false };
486 let new_var = types.write_to_c_conversion_new_var(w, &syn::Ident::new("ret", Span::call_site()), &rtype, generics, true);
488 write!(w, "\n\t{}", extra_indent).unwrap();
490 types.write_to_c_conversion_inline_prefix(w, &rtype, generics, true);
491 write!(w, "{}ret", if ret_returned && !new_var { "*" } else { "" }).unwrap();
492 types.write_to_c_conversion_inline_suffix(w, &rtype, generics, true);
499 /// Prints concrete generic parameters for a struct/trait/function, including the less-than and
500 /// greater-than symbols, if any generic parameters are defined.
501 pub fn maybe_write_generics<W: std::io::Write>(w: &mut W, generics: &syn::Generics, types: &TypeResolver, concrete_lifetimes: bool) {
502 let mut gen_types = GenericTypes::new();
503 assert!(gen_types.learn_generics(generics, types));
504 if !generics.params.is_empty() {
505 write!(w, "<").unwrap();
506 for (idx, generic) in generics.params.iter().enumerate() {
508 syn::GenericParam::Type(type_param) => {
509 let mut printed_param = false;
510 for bound in type_param.bounds.iter() {
511 if let syn::TypeParamBound::Trait(trait_bound) = bound {
512 assert_simple_bound(&trait_bound);
513 write!(w, "{}{}", if idx != 0 { ", " } else { "" }, gen_types.maybe_resolve_ident(&type_param.ident).unwrap()).unwrap();
515 unimplemented!("Can't print generic params that have multiple non-lifetime bounds");
517 printed_param = true;
521 syn::GenericParam::Lifetime(lt) => {
522 if concrete_lifetimes {
523 write!(w, "'static").unwrap();
525 write!(w, "{}'{}", if idx != 0 { ", " } else { "" }, lt.lifetime.ident).unwrap();
528 _ => unimplemented!(),
531 write!(w, ">").unwrap();