From 8d2a0ffe3784160389b491d5d7ee766d7802bb91 Mon Sep 17 00:00:00 2001
From: Felipe Pena <felipensp@gmail.com>
Date: Sun, 4 Jun 2023 13:10:22 -0300
Subject: [PATCH] cgen: fix option handling with auto heap variable (#18336)

---
 vlib/v/ast/ast.v                     | 11 ++++
 vlib/v/gen/c/assign.v                | 18 ++++++-
 vlib/v/gen/c/cgen.v                  | 76 +++++++++++++++++++++++-----
 vlib/v/tests/option_auto_heap_test.v | 24 +++++++++
 4 files changed, 116 insertions(+), 13 deletions(-)
 create mode 100644 vlib/v/tests/option_auto_heap_test.v

diff --git a/vlib/v/ast/ast.v b/vlib/v/ast/ast.v
index bd4c387b5b..3b0813ac17 100644
--- a/vlib/v/ast/ast.v
+++ b/vlib/v/ast/ast.v
@@ -962,6 +962,17 @@ pub mut:
 	concrete_types []Type
 }
 
+pub fn (i &Ident) is_auto_heap() bool {
+	match i.obj {
+		Var {
+			return i.obj.is_auto_heap
+		}
+		else {
+			return false
+		}
+	}
+}
+
 pub fn (i &Ident) is_mut() bool {
 	match i.obj {
 		Var {
diff --git a/vlib/v/gen/c/assign.v b/vlib/v/gen/c/assign.v
index eac7b14647..06a2e8cb3b 100644
--- a/vlib/v/gen/c/assign.v
+++ b/vlib/v/gen/c/assign.v
@@ -14,7 +14,12 @@ fn (mut g Gen) expr_with_opt_or_block(expr ast.Expr, expr_typ ast.Type, var_expr
 		g.inside_opt_or_res = true
 		g.expr_with_cast(expr, expr_typ, ret_typ)
 		g.writeln(';')
-		g.writeln('if (${expr}.state != 0) {')
+		expr_var := if expr is ast.Ident && (expr as ast.Ident).is_auto_heap() {
+			'(*${expr.name})'
+		} else {
+			'${expr}'
+		}
+		g.writeln('if (${expr_var}.state != 0) { // assign')
 		if expr is ast.Ident && (expr as ast.Ident).or_expr.kind == .propagate_option {
 			g.writeln('\tpanic_option_not_set(_SLIT("none"));')
 		} else {
@@ -623,6 +628,9 @@ fn (mut g Gen) assign_stmt(node_ ast.AssignStmt) {
 						g.inside_opt_or_res = old_inside_opt_or_res
 					}
 					g.inside_opt_or_res = true
+					if is_auto_heap && var_type.has_flag(.option) {
+						g.write('&')
+					}
 					tmp_var := g.new_tmp_var()
 					g.expr_with_tmp_var(val, val_type, var_type, tmp_var)
 				} else if is_fixed_array_var {
@@ -688,6 +696,14 @@ fn (mut g Gen) assign_stmt(node_ ast.AssignStmt) {
 						}
 					}
 				} else {
+					// var = &auto_heap_var
+					old_is_auto_heap := g.is_option_auto_heap
+					g.is_option_auto_heap = val_type.has_flag(.option) && val is ast.PrefixExpr
+						&& (val as ast.PrefixExpr).right is ast.Ident
+						&& ((val as ast.PrefixExpr).right as ast.Ident).is_auto_heap()
+					defer {
+						g.is_option_auto_heap = old_is_auto_heap
+					}
 					if var_type.has_flag(.option) || gen_or {
 						g.expr_with_opt_or_block(val, val_type, left, var_type)
 					} else if node.has_cross_var {
diff --git a/vlib/v/gen/c/cgen.v b/vlib/v/gen/c/cgen.v
index 11fb37834d..ec28db81a3 100644
--- a/vlib/v/gen/c/cgen.v
+++ b/vlib/v/gen/c/cgen.v
@@ -103,7 +103,8 @@ mut:
 	is_json_fn                bool // inside json.encode()
 	is_js_call                bool // for handling a special type arg #1 `json.decode(User, ...)`
 	is_fn_index_call          bool
-	is_cc_msvc                bool     // g.pref.ccompiler == 'msvc'
+	is_cc_msvc                bool // g.pref.ccompiler == 'msvc'
+	is_option_auto_heap       bool
 	vlines_path               string   // set to the proper path for generating #line directives
 	options_pos_forward       int      // insertion point to forward
 	options_forward           []string // to forward
@@ -3342,10 +3343,16 @@ fn (mut g Gen) expr(node_ ast.Expr) {
 					}
 				}
 			} else {
-				if !(g.is_amp && node.right.is_auto_deref_var()) {
+				if g.is_option_auto_heap {
+					g.write('(${g.base_type(node.right_type)}*)')
+				}
+				if !g.is_option_auto_heap && !(g.is_amp && node.right.is_auto_deref_var()) {
 					g.write(node.op.str())
 				}
 				g.expr(node.right)
+				if g.is_option_auto_heap {
+					g.write('.data')
+				}
 			}
 			g.is_amp = false
 		}
@@ -3560,8 +3567,10 @@ fn (mut g Gen) selector_expr(node ast.SelectorExpr) {
 	}
 	mut sum_type_deref_field := ''
 	mut sum_type_dot := '.'
+	mut field_typ := ast.void_type
 	if f := g.table.find_field_with_embeds(sym, node.field_name) {
 		field_sym := g.table.sym(f.typ)
+		field_typ = f.typ
 		if field_sym.kind in [.sum_type, .interface_] {
 			if !prevent_sum_type_unwrapping_once {
 				// check first if field is sum type because scope searching is expensive
@@ -3660,6 +3669,11 @@ fn (mut g Gen) selector_expr(node ast.SelectorExpr) {
 			return
 		}
 	}
+	field_is_opt := node.expr is ast.Ident && (node.expr as ast.Ident).is_auto_heap()
+		&& (node.expr as ast.Ident).or_expr.kind != .absent && field_typ.has_flag(.option)
+	if field_is_opt {
+		g.write('((${g.base_type(field_typ)})')
+	}
 	n_ptr := node.expr_type.nr_muls() - 1
 	if n_ptr > 0 {
 		g.write('(')
@@ -3669,6 +3683,9 @@ fn (mut g Gen) selector_expr(node ast.SelectorExpr) {
 	} else {
 		g.expr(node.expr)
 	}
+	if field_is_opt {
+		g.write(')')
+	}
 	if is_opt_or_res {
 		g.write('.data)')
 	}
@@ -3691,8 +3708,9 @@ fn (mut g Gen) selector_expr(node ast.SelectorExpr) {
 		}
 	}
 	alias_to_ptr := sym.info is ast.Alias && (sym.info as ast.Alias).parent_type.is_ptr()
-	if (node.expr_type.is_ptr() || sym.kind == .chan || alias_to_ptr)
-		&& node.from_embed_types.len == 0 {
+	if field_is_opt
+		|| ((node.expr_type.is_ptr() || sym.kind == .chan || alias_to_ptr)
+		&& node.from_embed_types.len == 0) {
 		g.write('->')
 	} else {
 		g.write('.')
@@ -4157,27 +4175,37 @@ fn (mut g Gen) ident(node ast.Ident) {
 			g.write('_const_')
 		}
 	}
-	mut is_auto_heap := false
+	mut is_auto_heap := node.is_auto_heap()
+	mut is_option := false
 	if node.info is ast.IdentVar {
 		if node.obj is ast.Var {
 			if !g.is_assign_lhs && node.obj.ct_type_var !in [.generic_param, .no_comptime] {
 				comptime_type := g.get_comptime_var_type(node)
 				if comptime_type.has_flag(.option) {
 					if (g.inside_opt_or_res || g.left_is_opt) && node.or_expr.kind == .absent {
-						g.write('${name}')
+						if !g.is_assign_lhs && is_auto_heap {
+							g.write('(*${name})')
+						} else {
+							g.write(name)
+						}
 					} else {
 						g.write('/*opt*/')
 						styp := g.base_type(comptime_type)
-						g.write('(*(${styp}*)${name}.data)')
+						if is_auto_heap {
+							g.write('(*(${styp}*)${name}->data)')
+						} else {
+							g.write('(*(${styp}*)${name}.data)')
+						}
 					}
 				} else {
-					g.write('${name}')
+					g.write(name)
 				}
 				if node.or_expr.kind != .absent && !(g.inside_opt_or_res && g.inside_assign
 					&& !g.is_assign_lhs) {
 					stmt_str := g.go_before_stmt(0).trim_space()
 					g.empty_line = true
-					g.or_block(name, node.or_expr, comptime_type)
+					var_name := if !g.is_assign_lhs && is_auto_heap { '(*${name})' } else { name }
+					g.or_block(var_name, node.or_expr, comptime_type)
 					g.writeln(stmt_str)
 				}
 				return
@@ -4189,17 +4217,30 @@ fn (mut g Gen) ident(node ast.Ident) {
 		// `println(x)` => `println(*(int*)x.data)`
 		if node.info.is_option && !(g.is_assign_lhs && g.right_is_opt) {
 			if (g.inside_opt_or_res || g.left_is_opt) && node.or_expr.kind == .absent {
-				g.write('${name}')
+				if !g.is_assign_lhs && is_auto_heap {
+					g.write('(*${name})')
+				} else {
+					g.write(name)
+				}
 			} else {
 				g.write('/*opt*/')
 				styp := g.base_type(node.info.typ)
-				g.write('(*(${styp}*)${name}.data)')
+				if is_auto_heap {
+					g.write('(*(${styp}*)${name}->data)')
+				} else {
+					g.write('(*(${styp}*)${name}.data)')
+				}
 			}
 			if node.or_expr.kind != .absent && !(g.inside_opt_or_res && g.inside_assign
 				&& !g.is_assign_lhs) {
 				stmt_str := g.go_before_stmt(0).trim_space()
 				g.empty_line = true
-				g.or_block(name, node.or_expr, node.info.typ)
+				var_name := if !g.is_assign_lhs && is_auto_heap {
+					'(*${name})'
+				} else {
+					name
+				}
+				g.or_block(var_name, node.or_expr, node.info.typ)
 				g.write(stmt_str)
 			}
 			return
@@ -4208,6 +4249,7 @@ fn (mut g Gen) ident(node ast.Ident) {
 			g.write('${name}.val')
 			return
 		}
+		is_option = node.info.is_option
 		if node.obj is ast.Var {
 			is_auto_heap = node.obj.is_auto_heap
 				&& (!g.is_assign_lhs || g.assign_op != .decl_assign)
@@ -4280,6 +4322,16 @@ fn (mut g Gen) ident(node ast.Ident) {
 	g.write(g.get_ternary_name(name))
 	if is_auto_heap {
 		g.write('))')
+		if is_option {
+			g.write('.data')
+		}
+	}
+	if node.or_expr.kind != .absent && !(g.inside_opt_or_res && g.inside_assign && !g.is_assign_lhs) {
+		stmt_str := g.go_before_stmt(0).trim_space()
+		g.empty_line = true
+		var_opt := if is_auto_heap { '(*${name})' } else { name }
+		g.or_block(var_opt, node.or_expr, node.obj.typ)
+		g.write(stmt_str)
 	}
 }
 
diff --git a/vlib/v/tests/option_auto_heap_test.v b/vlib/v/tests/option_auto_heap_test.v
new file mode 100644
index 0000000000..f918f66a79
--- /dev/null
+++ b/vlib/v/tests/option_auto_heap_test.v
@@ -0,0 +1,24 @@
+struct Teste {
+pub mut:
+	teste ?&Teste
+}
+
+fn test_main() {
+	mut a := Teste{}
+	a.teste = &a
+	dump(a) // circular
+
+	assert a.teste? == &a
+
+	mut t := ?Teste{}
+	w := dump(t) // Option(none)
+	assert w == none
+
+	mut z := ?Teste{}
+	z = Teste{}
+	z?.teste = &z
+	dump(z) // // circular
+
+	y := z?
+	assert y.teste? == &z?
+}