cgen: fix reassignment of optionals

vlib/net/http/http.v

@@ -20,7 +20,7 @@ pub mut:
 	url        string
 	user_agent string
 	verbose    bool
-mut:
+//mut:
 	user_ptr   voidptr
 	ws_func    voidptr
 }

vlib/v/gen/cgen.v

@@ -1371,7 +1371,7 @@ fn (mut g Gen) assign_expr(node ast.AssignExpr) {
 	tmp_opt := if gen_or { g.new_tmp_var() } else { '' }
 	if gen_or {
 		rstyp := g.typ(return_type)
-		g.write('$rstyp $tmp_opt =')
+		g.write('/*q*/ $rstyp $tmp_opt = ')
 	}
 	g.is_assign_rhs = true
 	if ast.expr_is_blank_ident(node.left) {
@@ -1406,12 +1406,16 @@ fn (mut g Gen) assign_expr(node ast.AssignExpr) {
 			}
 		} else {
 			g.assign_op = node.op
-			g.expr(node.left)
-			// arr[i] = val => `array_set(arr, i, val)`, not `array_get(arr, i) = val`
-			if !g.is_array_set && !str_add {
-				g.write(' $node.op.str() ')
-			} else if str_add {
-				g.write(', ')
+			if !gen_or {
+				// Don't need to generate `var = ` in `or {}` expressions, since we are doing
+				// `Option_X tmp = ...; var = *(X*)tmp.data;`
+				g.expr(node.left)
+				// arr[i] = val => `array_set(arr, i, val)`, not `array_get(arr, i) = val`
+				if !g.is_array_set && !str_add {
+					g.write(' $node.op.str() ')
+				} else if str_add {
+					g.write(', ')
+				}
 			}
 			g.is_assign_lhs = false
 			// right_sym := g.table.get_type_symbol(node.right_type)
@@ -1436,7 +1440,22 @@ fn (mut g Gen) assign_expr(node ast.AssignExpr) {
 		g.right_is_opt = false
 	}
 	if gen_or {
+		// g.write('/*777 $tmp_opt*/')
 		g.or_block(tmp_opt, or_stmts, return_type)
+		unwrapped_type_str := g.typ(return_type.set_flag(.unset))
+		ident := node.left as ast.Ident
+		if ident.info is ast.IdentVar {
+			ident_var := ident.info as ast.IdentVar
+			if ident_var.is_optional {
+				// var is already an optional, just copy the value
+				// `var = tmp;`
+				g.write('\n$ident.name = $tmp_opt')
+			} else {
+				// var = *(X*)tmp.data;`
+				g.write('\n$ident.name = *($unwrapped_type_str*)${tmp_opt}.data')
+			}
+		}
+		// g.expr(node.left)
 	}
 	g.is_assign_rhs = false
 }

vlib/v/tests/option_test.v

@@ -9,7 +9,7 @@ fn test_err_with_code() {
 		return
 	}
 	assert false
-	println(v)	// suppress not used error
+	println(v) // suppress not used error
 }
 
 fn opt_err() ?string {
@@ -22,7 +22,7 @@ fn test_err() {
 		return
 	}
 	assert false
-	println(v)	// suppress not used error
+	println(v) // suppress not used error
 }
 
 fn err_call(ok bool) ?int {
@@ -84,6 +84,25 @@ fn test_q() {
 	// assert foo_ok()? == true
 }
 
+fn test_reassignment() {
+	mut x2 := foo_ok() or {
+		assert false
+		return
+	}
+	assert x2 == 777
+	x2 = 100
+	assert x2 == 100
+	x2 += 1
+	assert x2 == 101
+	///
+	mut x3 := 0
+	x3 = foo_ok() or {
+		assert false
+		return
+	}
+	assert x3 == 777
+}
+
 struct Person {
 mut:
 	name  string
@@ -111,7 +130,7 @@ fn test_field_or() {
 		'default'
 	}
 	assert mytitle == 'default'
-*/
+	*/
 }
 
 struct Thing {
@@ -126,7 +145,7 @@ fn test_opt_field() {
 	t.opt = 5
 	val := t.opt or { return }
 	assert val == 5
-*/
+	*/
 }
 
 fn opt_ptr(a &int) ?&int {
@@ -137,6 +156,13 @@ fn opt_ptr(a &int) ?&int {
 }
 
 fn test_opt_ptr() {
+	if true {
+
+	}
+	//
+	else{
+
+	}
 	a := 3
 	mut r := opt_ptr(&a) or {
 		&int(0)