Support an annotation for generating bitfield sizes in C code (: SIZE)

Closes #609
Closes #611

src/bindgen/ir/field.rs

@@ -46,5 +46,8 @@ impl Source for Field {
     fn write<F: Write>(&self, config: &Config, out: &mut SourceWriter<F>) {
         self.documentation.write(config, out);
         cdecl::write_field(out, &self.ty, &self.name, config);
+        if let Some(bitfield) = self.annotations.atom("bitfield") {
+            write!(out, ": {}", bitfield.unwrap_or_default());
+        }
     }
 }

tests/expectations/bitfield.both.c

@@ -0,0 +1,11 @@
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+typedef struct HasBitfields {
+  uint64_t foo: 8;
+  uint64_t bar: 56;
+} HasBitfields;
+
+void root(const HasBitfields*);

tests/expectations/bitfield.both.compat.c

@@ -0,0 +1,19 @@
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+typedef struct HasBitfields {
+  uint64_t foo: 8;
+  uint64_t bar: 56;
+} HasBitfields;
+
+#ifdef __cplusplus
+extern "C" {
+#endif // __cplusplus
+
+void root(const HasBitfields*);
+
+#ifdef __cplusplus
+} // extern "C"
+#endif // __cplusplus

tests/expectations/bitfield.c

@@ -0,0 +1,11 @@
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+typedef struct {
+  uint64_t foo: 8;
+  uint64_t bar: 56;
+} HasBitfields;
+
+void root(const HasBitfields*);

tests/expectations/bitfield.compat.c

@@ -0,0 +1,19 @@
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+typedef struct {
+  uint64_t foo: 8;
+  uint64_t bar: 56;
+} HasBitfields;
+
+#ifdef __cplusplus
+extern "C" {
+#endif // __cplusplus
+
+void root(const HasBitfields*);
+
+#ifdef __cplusplus
+} // extern "C"
+#endif // __cplusplus

tests/expectations/bitfield.cpp

@@ -0,0 +1,16 @@
+#include <cstdarg>
+#include <cstdint>
+#include <cstdlib>
+#include <ostream>
+#include <new>
+
+struct HasBitfields {
+  uint64_t foo: 8;
+  uint64_t bar: 56;
+};
+
+extern "C" {
+
+void root(const HasBitfields*);
+
+} // extern "C"

tests/expectations/bitfield.tag.c

@@ -0,0 +1,11 @@
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+struct HasBitfields {
+  uint64_t foo: 8;
+  uint64_t bar: 56;
+};
+
+void root(const struct HasBitfields*);

tests/expectations/bitfield.tag.compat.c

@@ -0,0 +1,19 @@
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+struct HasBitfields {
+  uint64_t foo: 8;
+  uint64_t bar: 56;
+};
+
+#ifdef __cplusplus
+extern "C" {
+#endif // __cplusplus
+
+void root(const struct HasBitfields*);
+
+#ifdef __cplusplus
+} // extern "C"
+#endif // __cplusplus

tests/rust/bitfield/Cargo.lock

@@ -0,0 +1,5 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+[[package]]
+name = "bitfield"
+version = "0.1.0"

tests/rust/bitfield/Cargo.toml

@@ -0,0 +1,7 @@
+[package]
+name = "bitfield"
+version = "0.1.0"
+authors = ["cbindgen"]
+
+[features]
+cbindgen = []

tests/rust/bitfield/cbindgen.toml

@@ -0,0 +1,3 @@
+[parse.expand]
+crates = ["bitfield"]
+features = ["cbindgen"]

tests/rust/bitfield/src/lib.rs

@@ -0,0 +1,15 @@
+#[repr(C)]
+pub struct HasBitfields {
+    #[cfg(not(feature = "cbindgen"))]
+    foo_and_bar: u64,
+
+    #[cfg(feature = "cbindgen")]
+    /// cbindgen:bitfield=8
+    foo: u64,
+    #[cfg(feature = "cbindgen")]
+    /// cbindgen:bitfield=56
+    bar: u64,
+}
+
+#[no_mangle]
+pub extern "C" fn root(_: &HasBitfields) {}