Make sure finalisers are called for embedded fields

Previously, finalisers of embedded fields would never be called due to
embedded fields being transparent to the runtime. This change adds
calls to the adequate finalisers in parent objects' finalisers when
said parents contain embedded fields.

Closes #1551.

minimal-cases/finalisers/finalisers.pony

@@ -5,7 +5,13 @@ primitive PrimitiveInitFinal
   fun _final() =>
     @printf[I32]("primitive final\n".cstring())
 
+class EmbedFinal
+  fun _final() =>
+    @printf[I32]("embed final\n".cstring())
+
 class ClassFinal
+  embed f: EmbedFinal = EmbedFinal
+
   fun _final() =>
     @printf[I32]("class final\n".cstring())
 

src/libponyc/codegen/genfun.c

@@ -4,6 +4,7 @@
 #include "gentrace.h"
 #include "gencontrol.h"
 #include "genexpr.h"
+#include "genreference.h"
 #include "../pass/names.h"
 #include "../type/assemble.h"
 #include "../type/subtype.h"
@@ -216,6 +217,7 @@ static void make_prototype(compile_t* c, reach_type_t* t,
   {
     // Store the finaliser and use the C calling convention and an external
     // linkage.
+    assert(t->final_fn == NULL);
     t->final_fn = m->func;
     LLVMSetFunctionCallConv(m->func, LLVMCCallConv);
     LLVMSetLinkage(m->func, LLVMExternalLinkage);
@@ -285,6 +287,31 @@ static void add_dispatch_case(compile_t* c, reach_type_t* t, ast_t* params,
   ponyint_pool_free_size(buf_size, args);
 }
 
+static void call_embed_finalisers(compile_t* c, reach_type_t* t,
+  LLVMValueRef obj)
+{
+  uint32_t base = 0;
+  if(t->underlying != TK_STRUCT)
+    base++;
+
+  if(t->underlying == TK_ACTOR)
+    base++;
+
+  for(uint32_t i = 0; i < t->field_count; i++)
+  {
+    reach_field_t* field = &t->fields[i];
+    if(!field->embed)
+      continue;
+
+    LLVMValueRef final_fn = field->type->final_fn;
+    if(final_fn == NULL)
+      continue;
+
+    LLVMValueRef field_ref = LLVMBuildStructGEP(c->builder, obj, base + i, "");
+    LLVMBuildCall(c->builder, final_fn, &field_ref, 1, "");
+  }
+}
+
 static bool genfun_fun(compile_t* c, reach_type_t* t, reach_method_t* m)
 {
   assert(m->func != NULL);
@@ -295,6 +322,9 @@ static bool genfun_fun(compile_t* c, reach_type_t* t, reach_method_t* m)
   codegen_startfun(c, m->func, m->di_file, m->di_method);
   name_params(c, t, m, params, m->func);
 
+  if(m->func == t->final_fn)
+    call_embed_finalisers(c, t, gen_this(c, NULL));
+
   LLVMValueRef value = gen_expr(c, body);
 
   if(value == NULL)

src/libponyc/reach/reach.c

@@ -962,6 +962,14 @@ static void reachable_method(reach_t* r, ast_t* type, const char* name,
 
   if((n->id == TK_FUN) && ((n->cap == TK_BOX) || (n->cap == TK_TAG)))
   {
+    if(name == stringtab("_final"))
+    {
+      // If the method is a finaliser, don't mark the ref and val versions as
+      // reachable.
+      assert(n->cap == TK_BOX);
+      return;
+    }
+
     // TODO: if it doesn't use this-> in a constructor, we could reuse the
     // function, which means always reuse in a fun tag
     bool subordinate = (n->cap == TK_TAG);