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Allow case nil within a type switch statement (experimental idea)

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This commit is contained in:
gingerBill
2023-03-12 16:33:21 +00:00
parent f0ef10aa57
commit 93f7d3bfb9
2 changed files with 40 additions and 7 deletions
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28
src/check_stmt.cpp
View File

@@ -1184,6 +1184,8 @@ gb_internal void check_type_switch_stmt(CheckerContext *ctx, Ast *node, u32 mod_
return;
}
Ast *nil_seen = nullptr;
PtrSet<Type *> seen = {};
defer (ptr_set_destroy(&seen));
@@ -1194,6 +1196,7 @@ gb_internal void check_type_switch_stmt(CheckerContext *ctx, Ast *node, u32 mod_
}
ast_node(cc, CaseClause, stmt);
bool saw_nil = false;
// TODO(bill): Make robust
Type *bt = base_type(type_deref(x.type));
@@ -1202,6 +1205,25 @@ gb_internal void check_type_switch_stmt(CheckerContext *ctx, Ast *node, u32 mod_
if (type_expr != nullptr) { // Otherwise it's a default expression
Operand y = {};
check_expr_or_type(ctx, &y, type_expr);
if (is_operand_nil(y)) {
if (!type_has_nil(type_deref(x.type))) {
error(type_expr, "'nil' case is not allowed for the type '%s'", type_to_string(type_deref(x.type)));
continue;
}
saw_nil = true;
if (nil_seen) {
ERROR_BLOCK();
error(type_expr, "'nil' case has already been handled previously");
error_line("\t 'nil' was already previously seen at %s", token_pos_to_string(ast_token(nil_seen).pos));
} else {
nil_seen = type_expr;
}
case_type = y.type;
continue;
}
if (y.mode != Addressing_Type) {
gbString str = expr_to_string(type_expr);
error(type_expr, "Expected a type as a case, got %s", str);
@@ -1255,14 +1277,16 @@ gb_internal void check_type_switch_stmt(CheckerContext *ctx, Ast *node, u32 mod_
is_reference = true;
}
if (cc->list.count > 1) {
if (cc->list.count > 1 || saw_nil) {
case_type = nullptr;
}
if (case_type == nullptr) {
case_type = x.type;
}
if (switch_kind == TypeSwitch_Any) {
add_type_info_type(ctx, case_type);
if (!is_type_untyped(case_type)) {
add_type_info_type(ctx, case_type);
}
}
check_open_scope(ctx, stmt);

19
src/llvm_backend_stmt.cpp
View File

@@ -1423,9 +1423,11 @@ gb_internal void lb_build_type_switch_stmt(lbProcedure *p, AstTypeSwitchStmt *ss
continue;
}
Entity *case_entity = implicit_entity_of_node(clause);
max_size = gb_max(max_size, type_size_of(case_entity->type));
max_align = gb_max(max_align, type_align_of(case_entity->type));
variants_found = true;
if (!is_type_untyped_nil(case_entity->type)) {
max_size = gb_max(max_size, type_size_of(case_entity->type));
max_align = gb_max(max_align, type_align_of(case_entity->type));
variants_found = true;
}
}
if (variants_found) {
Type *t = alloc_type_array(t_u8, max_size);
@@ -1449,6 +1451,8 @@ gb_internal void lb_build_type_switch_stmt(lbProcedure *p, AstTypeSwitchStmt *ss
if (p->debug_info != nullptr) {
LLVMSetCurrentDebugLocation2(p->builder, lb_debug_location_from_ast(p, clause));
}
bool saw_nil = false;
for (Ast *type_expr : cc->list) {
Type *case_type = type_of_expr(type_expr);
lbValue on_val = {};
@@ -1457,7 +1461,12 @@ gb_internal void lb_build_type_switch_stmt(lbProcedure *p, AstTypeSwitchStmt *ss
on_val = lb_const_union_tag(m, ut, case_type);
} else if (switch_kind == TypeSwitch_Any) {
on_val = lb_typeid(m, case_type);
if (is_type_untyped_nil(case_type)) {
saw_nil = true;
on_val = lb_const_nil(m, t_typeid);
} else {
on_val = lb_typeid(m, case_type);
}
}
GB_ASSERT(on_val.value != nullptr);
LLVMAddCase(switch_instr, on_val.value, body->block);
@@ -1469,7 +1478,7 @@ gb_internal void lb_build_type_switch_stmt(lbProcedure *p, AstTypeSwitchStmt *ss
bool by_reference = (case_entity->flags & EntityFlag_Value) == 0;
if (cc->list.count == 1) {
if (cc->list.count == 1 && !saw_nil) {
lbValue data = {};
if (switch_kind == TypeSwitch_Union) {
data = union_data;