kit

commit 84391328a6db0a49e399438b7899ab18724949f5
parent 6e35c2a0243005dccb9ca712b84de24705e4d0f6
Author: Ryan Sepassi <rsepassi@gmail.com>
Date:   Mon, 25 May 2026 13:05:09 -0700

core: stabilize panic save layout across C environments

Diffstat:
M
src/core/core.c
 | 
3
+++
M
src/core/core.h
 | 
9
+++++++--

2 files changed, 10 insertions(+), 2 deletions(-)
diff --git a/src/core/core.c b/src/core/core.c
@@ -13,6 +13,9 @@
 #include "core/heap.h"
 #include "core/pool.h"
 
+_Static_assert(sizeof(jmp_buf) <= COMPILER_PANIC_BYTES,
+               "Compiler panic save buffer is too small for jmp_buf");
+
 SourceManager* source_new(Compiler*);
 void source_free(SourceManager*);
 
diff --git a/src/core/core.h b/src/core/core.h
@@ -107,8 +107,9 @@ void source_depiter_free(SourceDepIter*);
 
 typedef struct CompilerCleanup CompilerCleanup;
 
+#define COMPILER_PANIC_BYTES 256u
+
 struct CfreeCompiler {
-  jmp_buf panic;
   const CfreeContext* ctx;
   Pool* global;
   Arena* tu;
@@ -120,6 +121,10 @@ struct CfreeCompiler {
   const CfreeFrontendVTable* frontends[CFREE_LANG_COUNT];
   void* cg_api;
   void (*cg_api_free)(Compiler*);
+  /* Keep jmp_buf last: its size comes from the including C environment
+   * (host libc for some tests, rt/include for libcfree), and must not shift
+   * the offsets of the fields above across those builds. */
+  jmp_buf panic;
 };
 
 void compiler_init(Compiler*, Target, const CfreeContext*);
@@ -133,7 +138,7 @@ _Noreturn void compiler_panic(Compiler*, SrcLoc, const char* fmt, ...);
 _Noreturn void compiler_panicv(Compiler*, SrcLoc, const char* fmt, va_list);
 
 typedef struct PanicSave {
-  jmp_buf buf;
+  unsigned char buf[COMPILER_PANIC_BYTES];
 } PanicSave;
 void compiler_panic_save(Compiler*, PanicSave* out);
 void compiler_panic_restore(Compiler*, const PanicSave* saved);