Use C++ fixed-type enumeration syntax under C23 (or higher) as well

src/bindgen/ir/enumeration.rs

@@ -680,15 +680,20 @@ impl Enum {
                     }
                     write!(out, " {tag_name}");
 
-                    if config.cpp_compatible_c() {
-                        out.new_line();
-                        out.write("#ifdef __cplusplus");
-                        out.new_line();
-                        write!(out, "  : {prim}");
-                        out.new_line();
-                        out.write("#endif // __cplusplus");
-                        out.new_line();
-                    }
+                    // Emit typed enum syntax (valid in C23 or later or C++)
+                    let cond = if config.cpp_compatible_c() {
+                        "defined(__cplusplus) || __STDC_VERSION__ >= 202311L"
+                    } else {
+                        "__STDC_VERSION__ >= 202311L"
+                    };
+
+                    out.new_line();
+                    write!(out, "#if {cond}");
+                    out.new_line();
+                    write!(out, "  : {prim}");
+                    out.new_line();
+                    write!(out, "#endif // {cond}");
+                    out.new_line();
                 } else {
                     if config.style.generate_typedef() {
                         out.write("typedef ");
@@ -759,17 +764,39 @@ impl Enum {
         }
 
         // Emit typedef specifying the tag enum's size if necessary.
-        // In C++ enums can "inherit" from numeric types (`enum E: uint8_t { ... }`),
-        // but in C `typedef uint8_t E` is the only way to give a fixed size to `E`.
+        // In C++ or C23 enums can "inherit" from numeric types (`enum E: uint8_t { ... }`),
+        // but in older versions of C `typedef uint8_t E` is the only way to give a fixed size to `E`.
         if let Some(prim) = size {
             if config.cpp_compatible_c() {
                 out.new_line_if_not_start();
                 out.write("#ifndef __cplusplus");
             }
 
             if config.language != Language::Cxx {
+                if config.language == Language::C {
+                    out.new_line();
+                    out.write("#if __STDC_VERSION__ >= 202311L");
+
+                    out.new_line();
+                    write!(
+                        out,
+                        "{} enum {} {};",
+                        config.language.typedef(),
+                        tag_name,
+                        tag_name
+                    );
+
+                    out.new_line();
+                    out.write("#else");
+                }
+
                 out.new_line();
                 write!(out, "{} {} {};", config.language.typedef(), prim, tag_name);
+
+                if config.language == Language::C {
+                    out.new_line();
+                    out.write("#endif // __STDC_VERSION__ >= 202311L");
+                }
             }
 
             if config.cpp_compatible_c() {

tests/expectations/alias.c

@@ -3,11 +3,19 @@
 #include <stdint.h>
 #include <stdlib.h>
 
-enum Status {
+enum Status
+#if __STDC_VERSION__ >= 202311L
+  : uint32_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Ok,
   Err,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum Status Status;
+#else
 typedef uint32_t Status;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct {
   int32_t a;

tests/expectations/alias.compat.c

@@ -4,15 +4,19 @@
 #include <stdlib.h>
 
 enum Status
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint32_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Ok,
   Err,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum Status Status;
+#else
 typedef uint32_t Status;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct {

tests/expectations/alias_both.c

@@ -3,11 +3,19 @@
 #include <stdint.h>
 #include <stdlib.h>
 
-enum Status {
+enum Status
+#if __STDC_VERSION__ >= 202311L
+  : uint32_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Ok,
   Err,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum Status Status;
+#else
 typedef uint32_t Status;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct Dep {
   int32_t a;

tests/expectations/alias_both.compat.c

@@ -4,15 +4,19 @@
 #include <stdlib.h>
 
 enum Status
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint32_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Ok,
   Err,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum Status Status;
+#else
 typedef uint32_t Status;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct Dep {

tests/expectations/alias_tag.c

@@ -3,11 +3,19 @@
 #include <stdint.h>
 #include <stdlib.h>
 
-enum Status {
+enum Status
+#if __STDC_VERSION__ >= 202311L
+  : uint32_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Ok,
   Err,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum Status Status;
+#else
 typedef uint32_t Status;
+#endif // __STDC_VERSION__ >= 202311L
 
 struct Dep {
   int32_t a;

tests/expectations/alias_tag.compat.c

@@ -4,15 +4,19 @@
 #include <stdlib.h>
 
 enum Status
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint32_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Ok,
   Err,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum Status Status;
+#else
 typedef uint32_t Status;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 struct Dep {

tests/expectations/annotation.c

@@ -3,11 +3,19 @@
 #include <stdint.h>
 #include <stdlib.h>
 
-enum C {
+enum C
+#if __STDC_VERSION__ >= 202311L
+  : uint32_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   X = 2,
   Y,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum C C;
+#else
 typedef uint32_t C;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct {
   int32_t m0;
@@ -18,12 +26,20 @@ typedef struct {
   float y;
 } B;
 
-enum F_Tag {
+enum F_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Foo,
   Bar,
   Baz,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum F_Tag F_Tag;
+#else
 typedef uint8_t F_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct {
   F_Tag tag;
@@ -40,12 +56,20 @@ typedef union {
   Bar_Body bar;
 } F;
 
-enum H_Tag {
+enum H_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Hello,
   There,
   Everyone,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum H_Tag H_Tag;
+#else
 typedef uint8_t H_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct {
   uint8_t x;

tests/expectations/annotation.compat.c

@@ -4,15 +4,19 @@
 #include <stdlib.h>
 
 enum C
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint32_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   X = 2,
   Y,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum C C;
+#else
 typedef uint32_t C;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct {
@@ -25,16 +29,20 @@ typedef struct {
 } B;
 
 enum F_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Foo,
   Bar,
   Baz,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum F_Tag F_Tag;
+#else
 typedef uint8_t F_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct {
@@ -53,16 +61,20 @@ typedef union {
 } F;
 
 enum H_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Hello,
   There,
   Everyone,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum H_Tag H_Tag;
+#else
 typedef uint8_t H_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct {

tests/expectations/annotation_both.c

@@ -3,11 +3,19 @@
 #include <stdint.h>
 #include <stdlib.h>
 
-enum C {
+enum C
+#if __STDC_VERSION__ >= 202311L
+  : uint32_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   X = 2,
   Y,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum C C;
+#else
 typedef uint32_t C;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct A {
   int32_t m0;
@@ -18,12 +26,20 @@ typedef struct B {
   float y;
 } B;
 
-enum F_Tag {
+enum F_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Foo,
   Bar,
   Baz,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum F_Tag F_Tag;
+#else
 typedef uint8_t F_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct Bar_Body {
   F_Tag tag;
@@ -40,12 +56,20 @@ typedef union F {
   Bar_Body bar;
 } F;
 
-enum H_Tag {
+enum H_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Hello,
   There,
   Everyone,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum H_Tag H_Tag;
+#else
 typedef uint8_t H_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct There_Body {
   uint8_t x;