revert(vtable): 恢复按类实际规模动态分配

bf0bbcc 已经把固定上限去掉：收集前按「各父类 VTableMethodCount 之和 + 本类 FunctionDef 数 + 1」一次性分配三张表，越界检查保留为 InternalCompilerError。eff88dd 在并行开发中误把这段覆盖回固定 1024，这里恢复 bf0bbcc 的实现——无任意上限，且符合「能动态就动态」的既定规则。

App/lib/core/Gen/Class/ClassGenVTable.vp

@@ -18,10 +18,8 @@ import lib.core.Gen.DebugInfoGen as DebugInfoGen
 
 # Method metadata flag: TLS (@t.TLS decorator; local copy avoids a cross-module CDefine lookup).
 define META_TLS        = 32
-# Max number of vtable methods (per class). 32 was too small: large utility classes such as
-# memhub.MemBuddy declare well over 32 methods. The three slot arrays are PermPool-allocated
-# (8 * VTBL_METHOD_MAX each), so 1024 costs 24 KiB per class and survives pool resets.
-define VTBL_METHOD_MAX = 1024
+# Vtable method tables are sized per class at collection time (parents' count + own methods);
+# there is deliberately no fixed VTBL_METHOD_MAX.
 define SCOPE_FUNCTION  = 1
 
 # ============================================================
@@ -68,15 +66,35 @@ novirtual class ClassGenVTable(ClassGenBase.ClassGenBase):
         if children is None: return 0
         cn: sizet = len(children)
 
+        # Capacity comes from the class itself: the parents' already-collected vtable methods
+        # (an upper bound — dedupe/override only shrink it) plus the number of own method
+        # definitions. A fixed 32 silently dropped every later method, after which a call missed
+        # the slot and fell back to a static call of the base implementation.
+        parent_count: int = self.Gen.StructGen.get_parent_count(class_name)
+        vt_cap: int = 0
+        if parent_count > 0:
+            for pi0 in range(int(parent_count)):
+                pname0: str = self.Gen.StructGen.get_parent_name_at(class_name, pi0)
+                if pname0 is None: continue
+                pe0: GenTypes.StructEntry* = self.Gen.StructGen.find_struct_by_module(pname0, trans.ModuleSha1)
+                if pe0 is None: pe0 = self.Gen.StructGen.find_struct(pname0)
+                if pe0 is not None and pe0.VTableMethodCount > 0: vt_cap = vt_cap + pe0.VTableMethodCount
+        for ci0 in range(int(cn)):
+            stmt0: ast.AST* = children.get(ci0)
+            if stmt0 is not None and stmt0.kind() == ast.ASTKind.FunctionDef: vt_cap = vt_cap + 1
+        vt_cap = vt_cap + 1     # one spare slot
+        if vt_cap < 1: vt_cap = 1
+        vt_bytes: sizet = sizet(8 * vt_cap)
+
         # Allocate with PermPool: VTableMethods must survive per-file pool resets.
-        full_names_buf: sizet* = CompilerFactory.factory.PermPool.alloc(8 * VTBL_METHOD_MAX)
-        method_names_buf: sizet* = CompilerFactory.factory.PermPool.alloc(8 * VTBL_METHOD_MAX)
+        full_names_buf: sizet* = CompilerFactory.factory.PermPool.alloc(vt_bytes)
+        method_names_buf: sizet* = CompilerFactory.factory.PermPool.alloc(vt_bytes)
         # Record each method's parent SHA1 (non-zero = inherited, mangle with parent module SHA1).
-        method_parent_sha1s: sizet* = CompilerFactory.factory.PermPool.alloc(8 * VTBL_METHOD_MAX)
+        method_parent_sha1s: sizet* = CompilerFactory.factory.PermPool.alloc(vt_bytes)
         if full_names_buf is None or method_names_buf is None or method_parent_sha1s is None: return 0
-        string.memset(full_names_buf, 0, 8 * VTBL_METHOD_MAX)
-        string.memset(method_names_buf, 0, 8 * VTBL_METHOD_MAX)
-        string.memset(method_parent_sha1s, 0, 8 * VTBL_METHOD_MAX)
+        string.memset(full_names_buf, 0, vt_bytes)
+        string.memset(method_names_buf, 0, vt_bytes)
+        string.memset(method_parent_sha1s, 0, vt_bytes)
 
         method_count: int = 0
 
@@ -84,7 +102,6 @@ novirtual class ClassGenVTable(ClassGenBase.ClassGenBase):
         # subclass, others the parent; SHA1-aware lookup avoids cross-module same-name mismatches.
         vt_self_entry: GenTypes.StructEntry* = self.Gen.StructGen.find_struct_by_module(class_name, trans.ModuleSha1)
         # Multiple inheritance: walk parents in declaration order, dedupe by short name (first wins).
-        parent_count: int = self.Gen.StructGen.get_parent_count(class_name)
         if parent_count > 0:
             for pi in range(int(parent_count)):
                 pname: str = self.Gen.StructGen.get_parent_name_at(class_name, pi)
@@ -98,11 +115,10 @@ novirtual class ClassGenVTable(ClassGenBase.ClassGenBase):
                 if vt_parent_entry is not None: parent_vt_count = vt_parent_entry.VTableMethodCount
                 if parent_vt_count > 0:
                     for pvi in range(int(parent_vt_count)):
-                        if method_count >= VTBL_METHOD_MAX:
-                            # fail-fast: the VTableMethods arrays are fixed at VTBL_METHOD_MAX;
-                            # dropping the excess makes call sites miss the slot and silently fall
-                            # back to a static call of the base implementation.
-                            self.Gen.TypeGenErr.fatal_error(cd, f"class '{class_name}' inherits more than {VTBL_METHOD_MAX} virtual methods (compiler limit); raise VTBL_METHOD_MAX", "OverflowError")
+                        if method_count >= vt_cap:
+                            # Unreachable with the upper-bound sizing above; stay loud rather than
+                            # writing past the PermPool array.
+                            self.Gen.TypeGenErr.fatal_error(cd, f"internal error: vtable of '{class_name}' exceeded its computed capacity {vt_cap}", "InternalCompilerError")
                         pmethod_name: str = None
                         if vt_parent_entry is not None: pmethod_name = self.Gen.StructGen.get_vtable_method_name(pname, pvi)
                         if pmethod_name is None: continue
@@ -170,10 +186,10 @@ novirtual class ClassGenVTable(ClassGenBase.ClassGenBase):
             if stmt.kind() != ast.ASTKind.FunctionDef: continue
             fd: ast.FunctionDef* = ast.FunctionDef*(stmt)
             if fd is None or fd.name is None: continue
-            if method_count >= VTBL_METHOD_MAX:
-                # fail-fast: see the inheritance branch above; a dropped method silently loses
-                # its vtable slot (subclass override stops taking effect).
-                self.Gen.TypeGenErr.fatal_error(cd, f"class '{class_name}' declares more than {VTBL_METHOD_MAX} virtual methods (compiler limit); raise VTBL_METHOD_MAX", "OverflowError")
+            if method_count >= vt_cap:
+                # Unreachable with the upper-bound sizing above (own methods were counted);
+                # stay loud rather than writing past the PermPool array.
+                self.Gen.TypeGenErr.fatal_error(cd, f"internal error: vtable of '{class_name}' exceeded its computed capacity {vt_cap}", "InternalCompilerError")
 
             mname: str = fd.name
             # Skip constructors and special methods (they must not enter the vtable).