From e4ec4f0f95f44b131c256127d26c67258104be5a Mon Sep 17 00:00:00 2001
From: Mitchell Hashimoto <m@mitchellh.com>
Date: Thu, 13 Aug 2026 12:22:21 -0700
Subject: [PATCH] libghostty: fix enum underlying type detection

Use fixed int enum types for C++11, C23, Clang's fixed-enum extension,
and GCC 13 or newer. Previously only finalized C23 mode selected an explicit
underlying type, leaving C++ and common older C modes with
implementation-defined enum types.
---
 include/ghostty/vt/types.h | 36 +++++++++++++++++++++++++-----------
 1 file changed, 25 insertions(+), 11 deletions(-)

diff --git a/include/ghostty/vt/types.h b/include/ghostty/vt/types.h
index 672faa67c..bd3d37d65 100644
--- a/include/ghostty/vt/types.h
+++ b/include/ghostty/vt/types.h
@@ -39,18 +39,21 @@
  * The Zig side backs all C enums with c_int, so the C declarations
  * must use int as their underlying type to maintain ABI compatibility.
  *
- * C23 (detected via __STDC_VERSION__ >= 202311L) supports explicit
- * enum underlying types with `enum : int { ... }`. For pre-C23
- * compilers, which are free to choose any type that can represent
- * all values (C11 §6.7.2.2), we add an INT_MAX sentinel as the last
- * entry to force the compiler to use int.
+ * C++11 and C23 support explicit enum underlying types with
+ * `enum : int { ... }`. Clang and GCC 13+ also support this syntax as
+ * an extension in older C language modes, so use it when available.
+ *
+ * Other pre-C23 C compilers are free to choose any type that can
+ * represent all values (C11 §6.7.2.2). For those compilers, we add an
+ * INT_MAX sentinel as the last entry so the compatible type must be
+ * able to represent INT_MAX. The exact compatible type and its
+ * signedness remain implementation-defined in this fallback.
  *
  * INT_MAX is used rather than a fixed constant like 0xFFFFFFFF
- * because enum constants must have type int (which is signed).
- * Values above INT_MAX overflow signed int and are a constraint
- * violation in standard C; compilers that accept them interpret them
- * as negative values via two's complement, which can collide with
- * legitimate negative enum values.
+ * because enum constants must have type int in pre-C23 C. Values above
+ * INT_MAX are a constraint violation there; compilers that accept them
+ * may interpret them as negative values via two's complement, which can
+ * collide with legitimate negative enum values.
  *
  * Usage:
  * @code
@@ -61,7 +64,18 @@
  * } Foo;
  * @endcode
  */
-#if defined(__STDC_VERSION__) && __STDC_VERSION__ >= 202311L
+#if defined(__cplusplus) && \
+    (__cplusplus >= 201103L || (defined(_MSC_VER) && _MSC_VER >= 1700))
+#define GHOSTTY_ENUM_TYPED : int
+#elif defined(__STDC_VERSION__) && __STDC_VERSION__ >= 202311L
+#define GHOSTTY_ENUM_TYPED : int
+#elif defined(__clang__)
+  #if __has_extension(c_fixed_enum)
+    #define GHOSTTY_ENUM_TYPED : int
+  #else
+    #define GHOSTTY_ENUM_TYPED
+  #endif
+#elif defined(__GNUC__) && __GNUC__ >= 13
 #define GHOSTTY_ENUM_TYPED : int
 #else
 #define GHOSTTY_ENUM_TYPED