Add support for tagged enums that turn into structs.

This happens when the tags are separated. In this case the output is slightly
different since the tag is not part of the struct body, so we need the top-level
serializer to write the tag type.

Author: staktrace

src/bindgen/ir/enumeration.rs

@@ -797,24 +797,27 @@ impl Source for Enum {
                     .variants
                     .iter()
                     .map(|x| {
+                        let tag_str = format!("\"{}\"", x.export_name);
                         if let VariantBody::Body { ref name, .. } = x.body {
                             format!(
-                                "case {}::{}::{}: {} << {}.{}; break;",
+                                "case {}::{}::{}: {} << {}{}{}.{}; break;",
                                 self.export_name(),
                                 enum_name,
                                 x.export_name,
                                 stream,
+                                if separate_tag { &tag_str } else { "" },
+                                if separate_tag { " << " } else { "" },
                                 instance,
                                 name,
                             )
                         } else {
                             format!(
-                                "case {}::{}::{}: {} << \"{}\"; break;",
+                                "case {}::{}::{}: {} << {}; break;",
                                 self.export_name(),
                                 enum_name,
                                 x.export_name,
                                 stream,
-                                x.export_name,
+                                tag_str,
                             )
                         }
                     })

tests/expectations/both/derive_ostream.c

@@ -48,4 +48,28 @@ typedef union F {
   Bar_Body bar;
 } F;
 
-void root(A a, B b, C c, D d, F f);
+enum H_Tag {
+  Hello,
+  There,
+  Everyone,
+};
+typedef uint8_t H_Tag;
+
+typedef struct Hello_Body {
+  int16_t _0;
+} Hello_Body;
+
+typedef struct There_Body {
+  uint8_t x;
+  int16_t y;
+} There_Body;
+
+typedef struct H {
+  H_Tag tag;
+  union {
+    Hello_Body hello;
+    There_Body there;
+  };
+} H;
+
+void root(A a, B b, C c, D d, F f, H h);

tests/expectations/both/derive_ostream.compat.c

@@ -60,11 +60,41 @@ typedef union F {
   Bar_Body bar;
 } F;
 
+enum H_Tag
+#ifdef __cplusplus
+  : uint8_t
+#endif // __cplusplus
+ {
+  Hello,
+  There,
+  Everyone,
+};
+#ifndef __cplusplus
+typedef uint8_t H_Tag;
+#endif // __cplusplus
+
+typedef struct Hello_Body {
+  int16_t _0;
+} Hello_Body;
+
+typedef struct There_Body {
+  uint8_t x;
+  int16_t y;
+} There_Body;
+
+typedef struct H {
+  H_Tag tag;
+  union {
+    Hello_Body hello;
+    There_Body there;
+  };
+} H;
+
 #ifdef __cplusplus
 extern "C" {
 #endif // __cplusplus
 
-void root(A a, B b, C c, D d, F f);
+void root(A a, B b, C c, D d, F f, H h);
 
 #ifdef __cplusplus
 } // extern "C"

tests/expectations/derive_ostream.c

@@ -48,4 +48,28 @@ typedef union {
   Bar_Body bar;
 } F;
 
-void root(A a, B b, C c, D d, F f);
+enum H_Tag {
+  Hello,
+  There,
+  Everyone,
+};
+typedef uint8_t H_Tag;
+
+typedef struct {
+  int16_t _0;
+} Hello_Body;
+
+typedef struct {
+  uint8_t x;
+  int16_t y;
+} There_Body;
+
+typedef struct {
+  H_Tag tag;
+  union {
+    Hello_Body hello;
+    There_Body there;
+  };
+} H;
+
+void root(A a, B b, C c, D d, F f, H h);

tests/expectations/derive_ostream.compat.c

@@ -60,11 +60,41 @@ typedef union {
   Bar_Body bar;
 } F;
 
+enum H_Tag
+#ifdef __cplusplus
+  : uint8_t
+#endif // __cplusplus
+ {
+  Hello,
+  There,
+  Everyone,
+};
+#ifndef __cplusplus
+typedef uint8_t H_Tag;
+#endif // __cplusplus
+
+typedef struct {
+  int16_t _0;
+} Hello_Body;
+
+typedef struct {
+  uint8_t x;
+  int16_t y;
+} There_Body;
+
+typedef struct {
+  H_Tag tag;
+  union {
+    Hello_Body hello;
+    There_Body there;
+  };
+} H;
+
 #ifdef __cplusplus
 extern "C" {
 #endif // __cplusplus
 
-void root(A a, B b, C c, D d, F f);
+void root(A a, B b, C c, D d, F f, H h);
 
 #ifdef __cplusplus
 } // extern "C"

tests/expectations/derive_ostream.cpp

@@ -101,8 +101,58 @@ union F {
   Bar_Body bar;
 };
 
+struct H {
+  enum class Tag : uint8_t {
+    Hello,
+    There,
+    Everyone,
+  };
+
+  friend std::ostream& operator<<(std::ostream& stream, const Tag& instance) {
+    switch (instance) {
+      case H::Tag::Hello: stream << "Hello"; break;
+      case H::Tag::There: stream << "There"; break;
+      case H::Tag::Everyone: stream << "Everyone"; break;
+    }
+    return stream;
+  }
+
+  friend std::ostream& operator<<(std::ostream& stream, const H& instance) {
+    switch (instance.tag) {
+      case H::Tag::Hello: stream << "Hello" << instance.hello; break;
+      case H::Tag::There: stream << "There" << instance.there; break;
+      case H::Tag::Everyone: stream << "Everyone"; break;
+    }
+    return stream;
+  }
+
+  struct Hello_Body {
+    int16_t _0;
+
+    friend std::ostream& operator<<(std::ostream& stream, const Hello_Body& instance) {
+      return stream << "{ " << "_0=" << instance._0 << " }";
+    }
+  };
+
+  struct There_Body {
+    uint8_t x;
+    int16_t y;
+
+    friend std::ostream& operator<<(std::ostream& stream, const There_Body& instance) {
+      return stream << "{ " << "x=" << instance.x << ", "
+                            << "y=" << instance.y << " }";
+    }
+  };
+
+  Tag tag;
+  union {
+    Hello_Body hello;
+    There_Body there;
+  };
+};
+
 extern "C" {
 
-void root(A a, B b, C c, D d, F f);
+void root(A a, B b, C c, D d, F f, H h);
 
 } // extern "C"

tests/expectations/tag/derive_ostream.c

@@ -48,4 +48,28 @@ union F {
   struct Bar_Body bar;
 };
 
-void root(struct A a, struct B b, C c, struct D d, union F f);
+enum H_Tag {
+  Hello,
+  There,
+  Everyone,
+};
+typedef uint8_t H_Tag;
+
+struct Hello_Body {
+  int16_t _0;
+};
+
+struct There_Body {
+  uint8_t x;
+  int16_t y;
+};
+
+struct H {
+  H_Tag tag;
+  union {
+    struct Hello_Body hello;
+    struct There_Body there;
+  };
+};
+
+void root(struct A a, struct B b, C c, struct D d, union F f, struct H h);

tests/expectations/tag/derive_ostream.compat.c

@@ -60,11 +60,41 @@ union F {
   struct Bar_Body bar;
 };
 
+enum H_Tag
+#ifdef __cplusplus
+  : uint8_t
+#endif // __cplusplus
+ {
+  Hello,
+  There,
+  Everyone,
+};
+#ifndef __cplusplus
+typedef uint8_t H_Tag;
+#endif // __cplusplus
+
+struct Hello_Body {
+  int16_t _0;
+};
+
+struct There_Body {
+  uint8_t x;
+  int16_t y;
+};
+
+struct H {
+  H_Tag tag;
+  union {
+    struct Hello_Body hello;
+    struct There_Body there;
+  };
+};
+
 #ifdef __cplusplus
 extern "C" {
 #endif // __cplusplus
 
-void root(struct A a, struct B b, C c, struct D d, union F f);
+void root(struct A a, struct B b, C c, struct D d, union F f, struct H h);
 
 #ifdef __cplusplus
 } // extern "C"

tests/rust/derive_ostream.rs

@@ -30,12 +30,21 @@ enum F {
     Baz
 }
 
+/// cbindgen:derive-ostream
+#[repr(C, u8)]
+enum H {
+    Hello(i16),
+    There { x: u8, y: i16 },
+    Everyone
+}
+
 #[no_mangle]
 pub extern "C" fn root(
     a: A,
     b: B,
     c: C,
     d: D,
     f: F,
+    h: H,
 ) { }