New type GenericParam represents a generic parameter.

src/bindgen/ir/enumeration.rs

@@ -383,7 +383,7 @@ impl Enum {
         }
 
         let path = Path::new(item.ident.unraw().to_string());
-        let generic_params = GenericParams::new(&item.generics);
+        let generic_params = GenericParams::load(&item.generics)?;
 
         let mut variants = Vec::new();
         let mut has_data = false;
@@ -616,24 +616,7 @@ impl Item for Enum {
         library: &Library,
         out: &mut Monomorphs,
     ) {
-        assert!(
-            self.generic_params.len() > 0,
-            "{} is not generic",
-            self.path.name()
-        );
-        assert!(
-            self.generic_params.len() == generic_values.len(),
-            "{} has {} params but is being instantiated with {} values",
-            self.path.name(),
-            self.generic_params.len(),
-            generic_values.len(),
-        );
-
-        let mappings = self
-            .generic_params
-            .iter()
-            .zip(generic_values.iter())
-            .collect::<Vec<_>>();
+        let mappings = self.generic_params.call(self.path.name(), generic_values);
 
         for variant in &self.variants {
             if let VariantBody::Body { ref body, .. } = variant.body {

src/bindgen/ir/generic_path.rs

@@ -3,30 +3,95 @@ use std::ops::Deref;
 
 use syn::ext::IdentExt;
 
+use crate::bindgen::cdecl;
 use crate::bindgen::config::{Config, Language};
 use crate::bindgen::declarationtyperesolver::{DeclarationType, DeclarationTypeResolver};
 use crate::bindgen::ir::{ArrayLength, Path, Type};
 use crate::bindgen::utilities::IterHelpers;
 use crate::bindgen::writer::{Source, SourceWriter};
 
+#[derive(Debug, Clone)]
+pub enum GenericParamType {
+    Type,
+    Const(Type),
+}
+
+#[derive(Debug, Clone)]
+pub struct GenericParam {
+    name: Path,
+    ty: GenericParamType,
+}
+
+impl GenericParam {
+    pub fn new_type_param(name: &str) -> Self {
+        GenericParam {
+            name: Path::new(name),
+            ty: GenericParamType::Type,
+        }
+    }
+
+    pub fn load(param: &syn::GenericParam) -> Result<Option<Self>, String> {
+        match *param {
+            syn::GenericParam::Type(syn::TypeParam { ref ident, .. }) => Ok(Some(GenericParam {
+                name: Path::new(ident.unraw().to_string()),
+                ty: GenericParamType::Type,
+            })),
+
+            syn::GenericParam::Lifetime(_) => Ok(None),
+
+            syn::GenericParam::Const(syn::ConstParam {
+                ref ident, ref ty, ..
+            }) => match Type::load(ty)? {
+                None => {
+                    // A type that evaporates, like PhantomData.
+                    Err(format!("unsupported const generic type: {:?}", ty))
+                }
+                Some(ty) => Ok(Some(GenericParam {
+                    name: Path::new(ident.unraw().to_string()),
+                    ty: GenericParamType::Const(ty),
+                })),
+            },
+        }
+    }
+
+    pub fn name(&self) -> &Path {
+        &self.name
+    }
+}
+
 #[derive(Default, Debug, Clone)]
-pub struct GenericParams(pub Vec<Path>);
+pub struct GenericParams(pub Vec<GenericParam>);
 
 impl GenericParams {
-    pub fn new(generics: &syn::Generics) -> Self {
-        GenericParams(
-            generics
-                .params
-                .iter()
-                .filter_map(|x| match *x {
-                    syn::GenericParam::Type(syn::TypeParam { ref ident, .. })
-                    | syn::GenericParam::Const(syn::ConstParam { ref ident, .. }) => {
-                        Some(Path::new(ident.unraw().to_string()))
-                    }
-                    _ => None,
-                })
-                .collect(),
-        )
+    pub fn load(generics: &syn::Generics) -> Result<Self, String> {
+        let mut params = vec![];
+        for param in &generics.params {
+            if let Some(p) = GenericParam::load(param)? {
+                params.push(p);
+            }
+        }
+
+        Ok(GenericParams(params))
+    }
+
+    /// Associate each parameter with an argument.
+    pub fn call<'out>(
+        &'out self,
+        item_name: &str,
+        arguments: &'out [GenericArgument],
+    ) -> Vec<(&'out Path, &'out GenericArgument)> {
+        assert!(self.len() > 0, "{} is not generic", item_name);
+        assert!(
+            self.len() == arguments.len(),
+            "{} has {} params but is being instantiated with {} values",
+            item_name,
+            self.len(),
+            arguments.len(),
+        );
+        self.iter()
+            .map(|param| param.name())
+            .zip(arguments.iter())
+            .collect()
     }
 
     fn write_internal<F: Write>(
@@ -41,9 +106,19 @@ impl GenericParams {
                 if i != 0 {
                     out.write(", ");
                 }
-                write!(out, "typename {}", item);
-                if with_default {
-                    write!(out, " = void");
+                match item.ty {
+                    GenericParamType::Type => {
+                        write!(out, "typename {}", item.name);
+                        if with_default {
+                            write!(out, " = void");
+                        }
+                    }
+                    GenericParamType::Const(ref ty) => {
+                        cdecl::write_field(out, ty, item.name.name(), config);
+                        if with_default {
+                            write!(out, " = 0");
+                        }
+                    }
                 }
             }
             out.write(">");
@@ -57,9 +132,9 @@ impl GenericParams {
 }
 
 impl Deref for GenericParams {
-    type Target = [Path];
+    type Target = [GenericParam];
 
-    fn deref(&self) -> &[Path] {
+    fn deref(&self) -> &[GenericParam] {
         &self.0
     }
 }
@@ -168,7 +243,7 @@ impl GenericPath {
         for generic in &mut self.generics {
             generic.rename_for_config(config, generic_params);
         }
-        if !generic_params.contains(&self.path) {
+        if !generic_params.iter().any(|param| param.name == self.path) {
             config.export.rename(&mut self.export_name);
         }
     }

src/bindgen/ir/opaque.rs

@@ -35,7 +35,7 @@ impl OpaqueItem {
     ) -> Result<OpaqueItem, String> {
         Ok(Self::new(
             path,
-            GenericParams::new(generics),
+            GenericParams::load(generics)?,
             Cfg::append(mod_cfg, Cfg::load(attrs)),
             AnnotationSet::load(attrs).unwrap_or_else(|_| AnnotationSet::new()),
             Documentation::load(attrs),

src/bindgen/ir/structure.rs

@@ -103,7 +103,7 @@ impl Struct {
 
         Ok(Struct::new(
             path,
-            GenericParams::new(&item.generics),
+            GenericParams::load(&item.generics)?,
             fields,
             has_tag_field,
             is_enum_variant_body,
@@ -370,25 +370,7 @@ impl Item for Struct {
         library: &Library,
         out: &mut Monomorphs,
     ) {
-        assert!(
-            self.generic_params.len() > 0,
-            "{} is not generic",
-            self.path
-        );
-        assert!(
-            self.generic_params.len() == generic_values.len(),
-            "{} has {} params but is being instantiated with {} values",
-            self.path,
-            self.generic_params.len(),
-            generic_values.len(),
-        );
-
-        let mappings = self
-            .generic_params
-            .iter()
-            .zip(generic_values.iter())
-            .collect::<Vec<_>>();
-
+        let mappings = self.generic_params.call(self.path.name(), generic_values);
         let monomorph = self.specialize(generic_values, &mappings, library.get_config());
         out.insert_struct(library, self, monomorph, generic_values.to_owned());
     }

src/bindgen/ir/ty.rs

@@ -804,7 +804,7 @@ impl Type {
                     }
                 }
                 let path = generic.path();
-                if !generic_params.contains(path) {
+                if !generic_params.iter().any(|param| param.name() == path) {
                     if let Some(items) = library.get_items(path) {
                         if !out.items.contains(path) {
                             out.items.insert(path.clone());

src/bindgen/ir/typedef.rs

@@ -37,7 +37,7 @@ impl Typedef {
             let path = Path::new(item.ident.unraw().to_string());
             Ok(Typedef::new(
                 path,
-                GenericParams::new(&item.generics),
+                GenericParams::load(&item.generics)?,
                 x,
                 Cfg::append(mod_cfg, Cfg::load(&item.attrs)),
                 AnnotationSet::load(&item.attrs)?,
@@ -159,24 +159,7 @@ impl Item for Typedef {
         library: &Library,
         out: &mut Monomorphs,
     ) {
-        assert!(
-            self.generic_params.len() > 0,
-            "{} is not generic",
-            self.path
-        );
-        assert!(
-            self.generic_params.len() == generic_values.len(),
-            "{} has {} params but is being instantiated with {} values",
-            self.path,
-            self.generic_params.len(),
-            generic_values.len(),
-        );
-
-        let mappings = self
-            .generic_params
-            .iter()
-            .zip(generic_values.iter())
-            .collect::<Vec<_>>();
+        let mappings = self.generic_params.call(self.path.name(), generic_values);
 
         let mangled_path = mangle::mangle_path(
             &self.path,

src/bindgen/ir/union.rs

@@ -62,7 +62,7 @@ impl Union {
 
         Ok(Union::new(
             path,
-            GenericParams::new(&item.generics),
+            GenericParams::load(&item.generics)?,
             fields,
             repr.align,
             tuple_union,
@@ -227,24 +227,7 @@ impl Item for Union {
         library: &Library,
         out: &mut Monomorphs,
     ) {
-        assert!(
-            self.generic_params.len() > 0,
-            "{} is not generic",
-            self.path
-        );
-        assert!(
-            self.generic_params.len() == generic_values.len(),
-            "{} has {} params but is being instantiated with {} values",
-            self.path,
-            self.generic_params.len(),
-            generic_values.len(),
-        );
-
-        let mappings = self
-            .generic_params
-            .iter()
-            .zip(generic_values.iter())
-            .collect::<Vec<_>>();
+        let mappings = self.generic_params.call(self.path.name(), generic_values);
 
         let mangled_path = mangle::mangle_path(
             &self.path,

src/bindgen/parser.rs

@@ -15,8 +15,8 @@ use crate::bindgen::cargo::{Cargo, PackageRef};
 use crate::bindgen::config::{Config, ParseConfig};
 use crate::bindgen::error::Error;
 use crate::bindgen::ir::{
-    AnnotationSet, Cfg, Constant, Documentation, Enum, Function, GenericParams, ItemMap,
-    OpaqueItem, Path, Static, Struct, Type, Typedef, Union,
+    AnnotationSet, Cfg, Constant, Documentation, Enum, Function, GenericParam, GenericParams,
+    ItemMap, OpaqueItem, Path, Static, Struct, Type, Typedef, Union,
 };
 use crate::bindgen::utilities::{SynAbiHelpers, SynAttributeHelpers, SynItemFnHelpers};
 
@@ -425,7 +425,10 @@ impl Parse {
     pub fn add_std_types(&mut self) {
         let mut add_opaque = |path: &str, generic_params: Vec<&str>| {
             let path = Path::new(path);
-            let generic_params: Vec<_> = generic_params.into_iter().map(Path::new).collect();
+            let generic_params: Vec<_> = generic_params
+                .into_iter()
+                .map(GenericParam::new_type_param)
+                .collect();
             self.opaque_items.try_insert(OpaqueItem::new(
                 path,
                 GenericParams(generic_params),

tests/expectations/const_generics.both.c

@@ -0,0 +1,17 @@
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+#define TITLE_SIZE 80
+
+typedef int8_t CArrayString_TITLE_SIZE[TITLE_SIZE];
+
+typedef int8_t CArrayString_40[40];
+
+typedef struct Book {
+  CArrayString_TITLE_SIZE title;
+  CArrayString_40 author;
+} Book;
+
+void root(struct Book *a);

tests/expectations/const_generics.both.compat.c

@@ -0,0 +1,25 @@
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+#define TITLE_SIZE 80
+
+typedef int8_t CArrayString_TITLE_SIZE[TITLE_SIZE];
+
+typedef int8_t CArrayString_40[40];
+
+typedef struct Book {
+  CArrayString_TITLE_SIZE title;
+  CArrayString_40 author;
+} Book;
+
+#ifdef __cplusplus
+extern "C" {
+#endif // __cplusplus
+
+void root(struct Book *a);
+
+#ifdef __cplusplus
+} // extern "C"
+#endif // __cplusplus

tests/expectations/const_generics.c

@@ -0,0 +1,17 @@
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+#define TITLE_SIZE 80
+
+typedef int8_t CArrayString_TITLE_SIZE[TITLE_SIZE];
+
+typedef int8_t CArrayString_40[40];
+
+typedef struct {
+  CArrayString_TITLE_SIZE title;
+  CArrayString_40 author;
+} Book;
+
+void root(Book *a);

tests/expectations/const_generics.compat.c

@@ -0,0 +1,25 @@
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+#define TITLE_SIZE 80
+
+typedef int8_t CArrayString_TITLE_SIZE[TITLE_SIZE];
+
+typedef int8_t CArrayString_40[40];
+
+typedef struct {
+  CArrayString_TITLE_SIZE title;
+  CArrayString_40 author;
+} Book;
+
+#ifdef __cplusplus
+extern "C" {
+#endif // __cplusplus
+
+void root(Book *a);
+
+#ifdef __cplusplus
+} // extern "C"
+#endif // __cplusplus

tests/expectations/const_generics.cpp

@@ -0,0 +1,21 @@
+#include <cstdarg>
+#include <cstdint>
+#include <cstdlib>
+#include <ostream>
+#include <new>
+
+constexpr static const uintptr_t TITLE_SIZE = 80;
+
+template<uintptr_t CAP>
+using CArrayString = int8_t[CAP];
+
+struct Book {
+  CArrayString<TITLE_SIZE> title;
+  CArrayString<40> author;
+};
+
+extern "C" {
+
+void root(Book *a);
+
+} // extern "C"

tests/expectations/const_generics.pyx

@@ -0,0 +1,19 @@
+from libc.stdint cimport int8_t, int16_t, int32_t, int64_t, intptr_t
+from libc.stdint cimport uint8_t, uint16_t, uint32_t, uint64_t, uintptr_t
+cdef extern from *:
+  ctypedef bint bool
+  ctypedef struct va_list
+
+cdef extern from *:
+
+  const uintptr_t TITLE_SIZE # = 80
+
+  ctypedef int8_t CArrayString_TITLE_SIZE[TITLE_SIZE];
+
+  ctypedef int8_t CArrayString_40[40];
+
+  ctypedef struct Book:
+    CArrayString_TITLE_SIZE title;
+    CArrayString_40 author;
+
+  void root(Book *a);

tests/expectations/const_generics.tag.c

@@ -0,0 +1,17 @@
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+#define TITLE_SIZE 80
+
+typedef int8_t CArrayString_TITLE_SIZE[TITLE_SIZE];
+
+typedef int8_t CArrayString_40[40];
+
+struct Book {
+  CArrayString_TITLE_SIZE title;
+  CArrayString_40 author;
+};
+
+void root(struct Book *a);

tests/expectations/const_generics.tag.compat.c

@@ -0,0 +1,25 @@
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+#define TITLE_SIZE 80
+
+typedef int8_t CArrayString_TITLE_SIZE[TITLE_SIZE];
+
+typedef int8_t CArrayString_40[40];
+
+struct Book {
+  CArrayString_TITLE_SIZE title;
+  CArrayString_40 author;
+};
+
+#ifdef __cplusplus
+extern "C" {
+#endif // __cplusplus
+
+void root(struct Book *a);
+
+#ifdef __cplusplus
+} // extern "C"
+#endif // __cplusplus

tests/expectations/const_generics.tag.pyx

@@ -0,0 +1,19 @@
+from libc.stdint cimport int8_t, int16_t, int32_t, int64_t, intptr_t
+from libc.stdint cimport uint8_t, uint16_t, uint32_t, uint64_t, uintptr_t
+cdef extern from *:
+  ctypedef bint bool
+  ctypedef struct va_list
+
+cdef extern from *:
+
+  const uintptr_t TITLE_SIZE # = 80
+
+  ctypedef int8_t CArrayString_TITLE_SIZE[TITLE_SIZE];
+
+  ctypedef int8_t CArrayString_40[40];
+
+  cdef struct Book:
+    CArrayString_TITLE_SIZE title;
+    CArrayString_40 author;
+
+  void root(Book *a);

tests/expectations/const_generics_arrayvec.both.c

@@ -0,0 +1,11 @@
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+typedef struct ArrayVec_____u8__100 {
+  uint8_t *xs[100];
+  uint32_t len;
+} ArrayVec_____u8__100;
+
+int32_t push(struct ArrayVec_____u8__100 *v, uint8_t *elem);

tests/expectations/const_generics_arrayvec.both.compat.c

@@ -0,0 +1,19 @@
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+typedef struct ArrayVec_____u8__100 {
+  uint8_t *xs[100];
+  uint32_t len;
+} ArrayVec_____u8__100;
+
+#ifdef __cplusplus
+extern "C" {
+#endif // __cplusplus
+
+int32_t push(struct ArrayVec_____u8__100 *v, uint8_t *elem);
+
+#ifdef __cplusplus
+} // extern "C"
+#endif // __cplusplus

tests/expectations/const_generics_arrayvec.c

@@ -0,0 +1,11 @@
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+typedef struct {
+  uint8_t *xs[100];
+  uint32_t len;
+} ArrayVec_____u8__100;
+
+int32_t push(ArrayVec_____u8__100 *v, uint8_t *elem);

tests/expectations/const_generics_arrayvec.compat.c

@@ -0,0 +1,19 @@
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+typedef struct {
+  uint8_t *xs[100];
+  uint32_t len;
+} ArrayVec_____u8__100;
+
+#ifdef __cplusplus
+extern "C" {
+#endif // __cplusplus
+
+int32_t push(ArrayVec_____u8__100 *v, uint8_t *elem);
+
+#ifdef __cplusplus
+} // extern "C"
+#endif // __cplusplus

tests/expectations/const_generics_arrayvec.cpp

@@ -0,0 +1,17 @@
+#include <cstdarg>
+#include <cstdint>
+#include <cstdlib>
+#include <ostream>
+#include <new>
+
+template<typename T, uintptr_t CAP>
+struct ArrayVec {
+  T xs[CAP];
+  uint32_t len;
+};
+
+extern "C" {
+
+int32_t push(ArrayVec<uint8_t*, 100> *v, uint8_t *elem);
+
+} // extern "C"

tests/expectations/const_generics_arrayvec.pyx

@@ -0,0 +1,13 @@
+from libc.stdint cimport int8_t, int16_t, int32_t, int64_t, intptr_t
+from libc.stdint cimport uint8_t, uint16_t, uint32_t, uint64_t, uintptr_t
+cdef extern from *:
+  ctypedef bint bool
+  ctypedef struct va_list
+
+cdef extern from *:
+
+  ctypedef struct ArrayVec_____u8__100:
+    uint8_t *xs[100];
+    uint32_t len;
+
+  int32_t push(ArrayVec_____u8__100 *v, uint8_t *elem);

tests/expectations/const_generics_arrayvec.tag.c

@@ -0,0 +1,11 @@
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+struct ArrayVec_____u8__100 {
+  uint8_t *xs[100];
+  uint32_t len;
+};
+
+int32_t push(struct ArrayVec_____u8__100 *v, uint8_t *elem);

tests/expectations/const_generics_arrayvec.tag.compat.c

@@ -0,0 +1,19 @@
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+struct ArrayVec_____u8__100 {
+  uint8_t *xs[100];
+  uint32_t len;
+};
+
+#ifdef __cplusplus
+extern "C" {
+#endif // __cplusplus
+
+int32_t push(struct ArrayVec_____u8__100 *v, uint8_t *elem);
+
+#ifdef __cplusplus
+} // extern "C"
+#endif // __cplusplus

tests/expectations/const_generics_arrayvec.tag.pyx

@@ -0,0 +1,13 @@
+from libc.stdint cimport int8_t, int16_t, int32_t, int64_t, intptr_t
+from libc.stdint cimport uint8_t, uint16_t, uint32_t, uint64_t, uintptr_t
+cdef extern from *:
+  ctypedef bint bool
+  ctypedef struct va_list
+
+cdef extern from *:
+
+  cdef struct ArrayVec_____u8__100:
+    uint8_t *xs[100];
+    uint32_t len;
+
+  int32_t push(ArrayVec_____u8__100 *v, uint8_t *elem);

tests/rust/const_generics.rs

@@ -0,0 +1,15 @@
+#[repr(transparent)]
+pub struct CArrayString<const CAP: usize> {
+    pub chars: [i8; CAP],
+}
+
+pub const TITLE_SIZE: usize = 80;
+
+#[repr(C)]
+pub struct Book {
+    pub title: CArrayString<TITLE_SIZE>,
+    pub author: CArrayString<40>,
+}
+
+#[no_mangle]
+pub extern "C" fn root(a: *mut Book) {}

tests/rust/const_generics_arrayvec.rs

@@ -0,0 +1,17 @@
+#[repr(C)]
+pub struct ArrayVec<T, const CAP: usize> {
+    // the `len` first elements of the array are initialized
+    xs: [T; CAP],
+    len: u32,
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn push(v: *mut ArrayVec<*mut u8, 100>, elem: *mut u8) -> i32 {
+    if (*v).len < 100 {
+        (*v).xs[(*v).len] = elem;
+        (*v).len += 1;
+        1
+    } else {
+        0
+    }
+}