cgen: fix sum type match (#5978)

vlib/v/gen/cgen.v

@@ -99,6 +99,8 @@ mut:
 	inside_const          bool
 	comp_for_method       string // $for method in T {
 	comptime_var_type_map map[string]table.Type
+	match_sumtype_exprs   []ast.Expr
+	match_sumtype_syms    []table.TypeSymbol
 }
 
 const (
@@ -1760,6 +1762,9 @@ fn (mut g Gen) expr(node ast.Expr) {
 			g.write(node.val)
 		}
 		ast.Ident {
+			if g.should_write_asterisk_due_to_match_sumtype(node) {
+				g.write('*')
+			}
 			g.ident(node)
 		}
 		ast.IfExpr {
@@ -2269,6 +2274,16 @@ fn (mut g Gen) match_expr(node ast.MatchExpr) {
 		// g.write('/* EM ret type=${g.typ(node.return_type)}		expected_type=${g.typ(node.expected_type)}  */')
 	}
 	type_sym := g.table.get_type_symbol(node.cond_type)
+	if node.is_sum_type {
+		g.match_sumtype_exprs << node.cond
+		g.match_sumtype_syms << type_sym
+	}
+	defer {
+		if node.is_sum_type {
+			g.match_sumtype_exprs.pop()
+			g.match_sumtype_syms.pop()
+		}
+	}
 	mut tmp := ''
 	if type_sym.kind != .void {
 		tmp = g.new_tmp_var()
@@ -2417,6 +2432,36 @@ fn (mut g Gen) ident(node ast.Ident) {
 	g.write(g.get_ternary_name(name))
 }
 
+[unlikely]
+fn (mut g Gen) should_write_asterisk_due_to_match_sumtype(expr ast.Expr) bool {
+	if expr is ast.Ident {
+		typ := if expr.info is ast.IdentVar { (expr.info as ast.IdentVar).typ } else { (expr.info as ast.IdentFn).typ }
+		return if typ.is_ptr() && g.match_sumtype_has_no_struct_and_contains(expr) {
+			true
+		} else {
+			false
+		}
+	} else {
+		return false
+	}
+}
+
+[unlikely]
+fn (mut g Gen) match_sumtype_has_no_struct_and_contains(node ast.Ident) bool {
+	for i, expr in g.match_sumtype_exprs {
+		if expr is ast.Ident && node.name == (expr as ast.Ident).name {
+			sumtype := g.match_sumtype_syms[i].info as table.SumType
+			for typ in sumtype.variants {
+				if g.table.get_type_symbol(typ).kind == .struct_ {
+					return false
+				}
+			}
+			return true
+		}
+	}
+	return false
+}
+
 fn (mut g Gen) concat_expr(node ast.ConcatExpr) {
 	styp := g.typ(node.return_type)
 	sym := g.table.get_type_symbol(node.return_type)

vlib/v/gen/fn.v

@@ -391,7 +391,7 @@ fn (mut g Gen) method_call(node ast.CallExpr) {
 	// g.write('/*${g.typ(node.receiver_type)}*/')
 	// g.write('/*expr_type=${g.typ(node.left_type)} rec type=${g.typ(node.receiver_type)}*/')
 	// }
-	if !node.receiver_type.is_ptr() && node.left_type.is_ptr() && node.name == 'str' {
+	if !node.receiver_type.is_ptr() && node.left_type.is_ptr() && node.name == 'str' && !g.should_write_asterisk_due_to_match_sumtype(node.left) {
 		g.write('ptr_str(')
 	} else {
 		g.write('${name}(')

vlib/v/tests/sum_type_test.v

@@ -177,4 +177,95 @@ fn test_int_cast_to_sumtype() {
 			assert false
 		}
 	}
-}
+}
+
+// TODO: change definition once types other than any_int and any_float (int, f64, etc) are supported in sumtype
+type Number = any_int | any_float
+
+fn is_gt_simple(val string, dst Number) bool {
+	match dst {
+		any_int {
+			return val.int() > dst
+		}
+		any_float {
+			return dst < val.f64()
+		}
+	}
+}
+
+fn is_gt_nested(val string, dst Number) bool {
+	dst2 := dst
+	match dst {
+		any_int {
+			match dst2 {
+				any_int {
+					return val.int() > dst
+				}
+				// this branch should never been hit
+				else { 
+					return val.int() < dst 
+				}
+			}
+		}
+		any_float {
+			match dst2 {
+				any_float {
+					return dst < val.f64()
+				}
+				// this branch should never been hit
+				else { 
+					return dst > val.f64() 
+				}
+			}
+		}
+	}
+}
+
+fn concat(val string, dst Number) string {
+	match dst {
+		any_int {
+			mut res := val + '(int)'
+			res += dst.str()
+			return res
+		}
+		any_float {
+			mut res := val + '(float)'
+			res += dst.str()
+			return res
+		}
+	}
+}
+
+fn get_sum(val string, dst Number) f64 {
+	match dst {
+		any_int {
+			mut res := val.int()
+			res += dst
+			return res
+		}
+		any_float {
+			mut res := val.f64()
+			res += dst
+			return res
+		}
+	}
+}
+
+fn test_sum_type_match() {
+	assert is_gt_simple('3', 2)
+	assert !is_gt_simple('3', 5)
+	assert is_gt_simple('3', 1.2)
+	assert !is_gt_simple('3', 3.5)	
+	assert is_gt_nested('3', 2)
+	assert !is_gt_nested('3', 5)
+	assert is_gt_nested('3', 1.2)
+	assert !is_gt_nested('3', 3.5)
+	assert concat('3', 2) == '3(int)2'
+	assert concat('3', 5) == '3(int)5'
+	assert concat('3', 1.2) == '3(float)1.2'
+	assert concat('3', 3.5) == '3(float)3.5'
+	assert get_sum('3', 2) == 5.0
+	assert get_sum('3', 5) == 8.0
+	assert get_sum('3', 1.2) == 4.2
+	assert get_sum('3', 3.5) == 6.5
+}