fix(match): case 体末句控制流全 return 补 unreachable 不 br end_bb
根因（ClassGenEnum._get_type_align 掉出末尾）：case 体末句是 If/控制流且 全分支 return 时，处理器把 builder 停在无 terminator 的 merge 块，case 循环的 is_terminated 误判未终止 → 补 br end_bb → rm/sq/sm_merge_reach=1 → 全 case return 的 match 被误判 merge 可达 → 函数收尾 fail-fast '流程掉出末尾'。新增模块级 _case_tail_unreachable：末句控制流 （If/While/For/Match）且 _ctrl_merge_reachable==0 时补 unreachable， 与 HandlesIf L309-315 / ClassGenVTable L1084 同语义；应用于 renum/ sequence/simple 三路的 case 体与 default 收尾（不含 Try/With，其处理器 不维护该标志）。
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@@ -44,6 +44,44 @@ MAX_MATCH_CASES: t.CDefine = 32
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SCOPE_MATCH: t.CDefine = 6
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# ============================================================
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# _case_tail_unreachable - case 体末尾结构性不可达判定
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#
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# case 体翻译后当前块若未终止，且末句是控制流语句（If/While/For/Match）
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# 且其 merge 结构性不可达（全分支 return，如 case Int(bits): if ... return）
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# 时，当前块是控制流的 merge（无 terminator），与 HandlesIf L309-315/
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# ClassGenVTable L1084 同语义补 unreachable。返回 1= 已补 unreachable
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# （调用方不应 br end_bb）；0= 正常收尾（应 br end_bb）。
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#
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# 根因（ClassGenEnum._get_type_align）：case 体末句 If 全 return 时，If
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# 处理器把 builder 停在无 terminator 的 merge 块，case 循环的
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# is_terminated 检查误判"未终止" → 补 br end_bb → rm_merge_reach=1 →
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# 全 case return 的 match 被误判 merge 可达 → 函数收尾 fail-fast
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# "流程掉出末尾"。不含 Try/With：其处理器不维护 _ctrl_merge_reachable，
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# 避免残留值误判。
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# ============================================================
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def _case_tail_unreachable(trans: HT.Translator | t.CPtr,
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builder: llvmlite.IRBuilder | t.CPtr,
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body_list: list[ast.AST | t.CPtr] | t.CPtr) -> int:
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if trans is None or builder is None:
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return 0
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if llvmlite.builder_cur_block_is_terminated(builder) != 0:
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return 0
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if body_list is None or len(body_list) == 0:
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return 0
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lst: ast.AST | t.CPtr = body_list.get(len(body_list) - 1)
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if lst is None:
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return 0
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lk: int = lst.kind()
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if lk != ast.ASTKind.If and lk != ast.ASTKind.While \
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and lk != ast.ASTKind.For and lk != ast.ASTKind.Match:
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return 0
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if trans._ctrl_merge_reachable != 0:
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return 0
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llvmlite.build_unreachable(builder)
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return 1
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# ============================================================
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# 全局 gen 单例（模块级镜像，同 HandlesStruct 模式）
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#
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@@ -519,8 +557,10 @@ class MatchHandle(HandlesBase.Mixin):
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HandlesVar.exit_scope(trans.SymTab)
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# 若未终止且无 NoBreak，跳到 end
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# 末句控制流全 return（结构性不可达）时补 unreachable，不 br end_bb
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if llvmlite.builder_cur_block_is_terminated(builder) == 0 \
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and nb == 0:
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and nb == 0 \
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and _case_tail_unreachable(trans, builder, body_list) == 0:
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llvmlite.build_br(builder, end_bb)
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trans._ctrl_merge_reachable = 1
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rm_merge_reach = 1
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@@ -537,6 +577,7 @@ class MatchHandle(HandlesBase.Mixin):
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rm_merge_reach = 1
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else:
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# 有显式 default：翻译 default case body（找到 is_def==1 的 case）
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dbody: list[ast.AST | t.CPtr] | t.CPtr = None
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di: int = 0
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while di < collected:
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if def_arr[di] == 1:
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@@ -545,7 +586,7 @@ class MatchHandle(HandlesBase.Mixin):
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dmc: ast.MatchCase | t.CPtr = (
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ast.MatchCase | t.CPtr)(dcase)
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HandlesVar.enter_scope(trans.SymTab, SCOPE_MATCH)
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dbody: list[ast.AST | t.CPtr] | t.CPtr = dmc.children
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dbody = dmc.children
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if dbody is not None:
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dn: t.CSizeT = len(dbody)
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dj: int = 0
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@@ -557,7 +598,9 @@ class MatchHandle(HandlesBase.Mixin):
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HandlesVar.exit_scope(trans.SymTab)
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break
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di = di + 1
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if llvmlite.builder_cur_block_is_terminated(builder) == 0:
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# 末句控制流全 return → 补 unreachable（不 br end_bb）
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if llvmlite.builder_cur_block_is_terminated(builder) == 0 \
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and _case_tail_unreachable(trans, builder, dbody) == 0:
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llvmlite.build_br(builder, end_bb)
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trans._ctrl_merge_reachable = 1
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rm_merge_reach = 1
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@@ -988,7 +1031,9 @@ class MatchHandle(HandlesBase.Mixin):
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HandlesBody.translate_stmt(trans, stmt)
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bi = bi + 1
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HandlesVar.exit_scope(trans.SymTab)
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if llvmlite.builder_cur_block_is_terminated(builder) == 0:
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# 末句控制流全 return → 补 unreachable（不 br end，无 fallthrough）
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if llvmlite.builder_cur_block_is_terminated(builder) == 0 \
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and _case_tail_unreachable(trans, builder, body_list2) == 0:
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if nb_arr[ci] == 0:
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llvmlite.build_br(builder, end_bb)
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else:
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@@ -1011,6 +1056,7 @@ class MatchHandle(HandlesBase.Mixin):
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# 7. default 块
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llvmlite.position_at_end(builder, default_bb)
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dbody: list[ast.AST | t.CPtr] | t.CPtr = None
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if has_default == 1:
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di: int = 0
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while di < collected:
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@@ -1020,7 +1066,7 @@ class MatchHandle(HandlesBase.Mixin):
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dmc: ast.MatchCase | t.CPtr = (
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ast.MatchCase | t.CPtr)(dnode)
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HandlesVar.enter_scope(trans.SymTab, SCOPE_MATCH)
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dbody: list[ast.AST | t.CPtr] | t.CPtr = dmc.children
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dbody = dmc.children
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if dbody is not None:
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dn: t.CSizeT = len(dbody)
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dj: int = 0
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@@ -1032,7 +1078,9 @@ class MatchHandle(HandlesBase.Mixin):
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HandlesVar.exit_scope(trans.SymTab)
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break
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di = di + 1
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if llvmlite.builder_cur_block_is_terminated(builder) == 0:
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# 末句控制流全 return → 补 unreachable（不 br end_bb）
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if llvmlite.builder_cur_block_is_terminated(builder) == 0 \
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and _case_tail_unreachable(trans, builder, dbody) == 0:
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llvmlite.build_br(builder, end_bb)
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sq_merge_reach = 1
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@@ -1227,8 +1275,10 @@ class MatchHandle(HandlesBase.Mixin):
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HandlesVar.exit_scope(trans.SymTab)
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# 末句控制流全 return → 补 unreachable（不 br end_bb）
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if llvmlite.builder_cur_block_is_terminated(builder) == 0 \
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and nb == 0:
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and nb == 0 \
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and _case_tail_unreachable(trans, builder, body_list) == 0:
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llvmlite.build_br(builder, end_bb)
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trans._ctrl_merge_reachable = 1
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sm_merge_reach = 1
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@@ -1243,6 +1293,7 @@ class MatchHandle(HandlesBase.Mixin):
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trans._ctrl_merge_reachable = 1
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sm_merge_reach = 1
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else:
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dbody: list[ast.AST | t.CPtr] | t.CPtr = None
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di: int = 0
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while di < collected:
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if def_arr[di] == 1:
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@@ -1251,7 +1302,7 @@ class MatchHandle(HandlesBase.Mixin):
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dmc: ast.MatchCase | t.CPtr = (
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ast.MatchCase | t.CPtr)(dcase)
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HandlesVar.enter_scope(trans.SymTab, SCOPE_MATCH)
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dbody: list[ast.AST | t.CPtr] | t.CPtr = dmc.children
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dbody = dmc.children
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if dbody is not None:
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dn: t.CSizeT = len(dbody)
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dj: int = 0
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@@ -1263,7 +1314,9 @@ class MatchHandle(HandlesBase.Mixin):
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HandlesVar.exit_scope(trans.SymTab)
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break
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di = di + 1
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if llvmlite.builder_cur_block_is_terminated(builder) == 0:
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# 末句控制流全 return → 补 unreachable（不 br end_bb）
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if llvmlite.builder_cur_block_is_terminated(builder) == 0 \
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and _case_tail_unreachable(trans, builder, dbody) == 0:
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llvmlite.build_br(builder, end_bb)
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trans._ctrl_merge_reachable = 1
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sm_merge_reach = 1
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