Revert "flake: update nixpkgs pin 23.11->24.05 (+ boehmgc compat changes)"

This reverts commit 28a079f841.

Reason for revert: This caused a pile of regressions in CI, and does not pass nix flake check. Some number of them are fixed in CL: https://gerrit.lix.systems/c/lix/+/1429 but there's more to be fixed.

We should defer this after 2.90.

Change-Id: Ib839d0fcb08eb52094af2b521145e3c1b4e0556f

boehmgc-coroutine-sp-fallback.diff

@@ -1,8 +1,56 @@
+diff --git a/darwin_stop_world.c b/darwin_stop_world.c
+index 0468aaec..b348d869 100644
+--- a/darwin_stop_world.c
++++ b/darwin_stop_world.c
+@@ -356,6 +356,7 @@ GC_INNER void GC_push_all_stacks(void)
+   int nthreads = 0;
+   word total_size = 0;
+   mach_msg_type_number_t listcount = (mach_msg_type_number_t)THREAD_TABLE_SZ;
++  size_t stack_limit;
+   if (!EXPECT(GC_thr_initialized, TRUE))
+     GC_thr_init();
+
+@@ -411,6 +412,19 @@ GC_INNER void GC_push_all_stacks(void)
+             GC_push_all_stack_sections(lo, hi, p->traced_stack_sect);
+           }
+           if (altstack_lo) {
++            // When a thread goes into a coroutine, we lose its original sp until
++            // control flow returns to the thread.
++            // While in the coroutine, the sp points outside the thread stack,
++            // so we can detect this and push the entire thread stack instead,
++            // as an approximation.
++            // We assume that the coroutine has similarly added its entire stack.
++            // This could be made accurate by cooperating with the application
++            // via new functions and/or callbacks.
++            stack_limit = pthread_get_stacksize_np(p->id);
++            if (altstack_lo >= altstack_hi || altstack_lo < altstack_hi - stack_limit) { // sp outside stack
++              altstack_lo = altstack_hi - stack_limit;
++            }
++
+             total_size += altstack_hi - altstack_lo;
+             GC_push_all_stack(altstack_lo, altstack_hi);
+           }
+diff --git a/include/gc.h b/include/gc.h
+index edab6c22..f2c61282 100644
+--- a/include/gc.h
++++ b/include/gc.h
+@@ -2172,6 +2172,11 @@ GC_API void GC_CALL GC_win32_free_heap(void);
+         (*GC_amiga_allocwrapper_do)(a,GC_malloc_atomic_ignore_off_page)
+ #endif /* _AMIGA && !GC_AMIGA_MAKINGLIB */
+
++#if !__APPLE__
++/* Patch doesn't work on apple */
++#define NIX_BOEHM_PATCH_VERSION 1
++#endif
++
+ #ifdef __cplusplus
+   } /* extern "C" */
+ #endif
 diff --git a/pthread_stop_world.c b/pthread_stop_world.c
-index 2b45489..0e6d8ef 100644
+index b5d71e62..aed7b0bf 100644
 --- a/pthread_stop_world.c
 +++ b/pthread_stop_world.c
-@@ -776,6 +776,8 @@ STATIC void GC_restart_handler(int sig)
+@@ -768,6 +768,8 @@ STATIC void GC_restart_handler(int sig)
  /* world is stopped.  Should not fail if it isn't.                      */
  GC_INNER void GC_push_all_stacks(void)
  {
@@ -11,23 +59,20 @@ index 2b45489..0e6d8ef 100644
      GC_bool found_me = FALSE;
      size_t nthreads = 0;
      int i;
-@@ -868,6 +870,40 @@ GC_INNER void GC_push_all_stacks(void)
+@@ -851,6 +853,37 @@ GC_INNER void GC_push_all_stacks(void)
            hi = p->altstack + p->altstack_size;
- #         endif
            /* FIXME: Need to scan the normal stack too, but how ? */
+           /* FIXME: Assume stack grows down */
 +        } else {
 +#ifdef HAVE_PTHREAD_ATTR_GET_NP
-+          if (pthread_attr_init(&pattr) != 0) {
++          if (!pthread_attr_init(&pattr)
-+            ABORT("GC_push_all_stacks: pthread_attr_init failed!");
++              || !pthread_attr_get_np(p->id, &pattr))
-+          }
++#else /* HAVE_PTHREAD_GETATTR_NP */
-+          if (pthread_attr_get_np(p->id, &pattr) != 0) {
++          if (pthread_getattr_np(p->id, &pattr))
-+            ABORT("GC_push_all_stacks: pthread_attr_get_np failed!");
++#endif
-+          }
++          {
-+          #else
-+          if (pthread_getattr_np(p->id, &pattr)) {
 +            ABORT("GC_push_all_stacks: pthread_getattr_np failed!");
 +          }
-+          #endif
 +          if (pthread_attr_getstacksize(&pattr, &stack_limit)) {
 +            ABORT("GC_push_all_stacks: pthread_attr_getstacksize failed!");
 +          }
@@ -50,5 +95,5 @@ index 2b45489..0e6d8ef 100644
 +          #error "STACK_GROWS_UP not supported in boost_coroutine2 (as of june 2021), so we don't support it in Nix."
 +          #endif
          }
- #       ifdef STACKPTR_CORRECTOR_AVAILABLE
+         GC_push_all_stack_sections(lo, hi, traced_stack_sect);
-           if (GC_sp_corrector != 0)
+ #       ifdef STACK_GROWS_UP

boehmgc-traceable_allocator-public.diff

@@ -0,0 +1,12 @@
+diff --git a/include/gc_allocator.h b/include/gc_allocator.h
+index 597c7f13..587286be 100644
+--- a/include/gc_allocator.h
++++ b/include/gc_allocator.h
+@@ -312,6 +312,7 @@ public:
+
+ template<>
+ class traceable_allocator<void> {
++public:
+   typedef size_t      size_type;
+   typedef ptrdiff_t   difference_type;
+   typedef void*       pointer;

flake.lock

@@ -18,16 +18,16 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1717796960,
+        "lastModified": 1715123187,
-        "narHash": "sha256-BKjQ9tQdsuoROrojHZb7KTAv95WprqCkNFvuzatfEo0=",
+        "narHash": "sha256-0czuu757t53lK6uWeo1a5/jJbCd9t4sOtLDFpts60DM=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "8e0a5f16b7bf7f212be068dd302c49888c6ad68f",
+        "rev": "0c592f9a288bdf764b6f24c757277c0e49757a46",
         "type": "github"
       },
       "original": {
         "owner": "NixOS",
-        "ref": "nixos-24.05-small",
+        "ref": "nixos-23.11-small",
         "repo": "nixpkgs",
         "type": "github"
       }

flake.nix

@@ -2,7 +2,7 @@
   description = "The purely functional package manager";
 
   inputs = {
-    nixpkgs.url = "github:NixOS/nixpkgs/nixos-24.05-small";
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-23.11-small";
     nixpkgs-regression.url = "github:NixOS/nixpkgs/215d4d0fd80ca5163643b03a33fde804a29cc1e2";
     pre-commit-hooks = {
       url = "github:cachix/git-hooks.nix";

meson.build

@@ -189,7 +189,7 @@ configdata = { }
 # Dependencies
 #
 
-boehm = dependency('bdw-gc', required : get_option('gc'), version : '>=8.2.6')
+boehm = dependency('bdw-gc', required : get_option('gc'))
 if boehm.found()
   deps += boehm
 endif

package.nix

@@ -70,6 +70,8 @@
         # `boehmgc-nix` then this will almost certainly have duplicate patches, which means
         # the patches won't apply and we'll get a build failure.
         ./boehmgc-coroutine-sp-fallback.diff
+        # https://github.com/ivmai/bdwgc/pull/586
+        ./boehmgc-traceable_allocator-public.diff
       ];
     };