checker: improve fn argument mismatch error

vlib/v/checker/fn.v

@@ -1,5 +1,6 @@
 module checker
 
+import strings
 import v.ast
 import v.util
 import v.token
@@ -2863,7 +2864,8 @@ struct HaveWantParams {
 }
 
 fn (mut c Checker) fn_call_error_have_want(p HaveWantParams) {
-	mut have_want := '\n\thave ('
+	mut sb := strings.new_builder(20)
+	sb.write_string('have (')
 	// Fetch arg types, they are always 0 at this point
 	// Duplicate logic, but we don't care, since this is an error, so no perf cost
 	mut arg_types := []ast.Type{len: p.args.len}
@@ -2876,30 +2878,32 @@ fn (mut c Checker) fn_call_error_have_want(p HaveWantParams) {
 		if arg_types[i] == 0 { // arg.typ == 0 {
 			// Arguments can have an unknown (invalid) type
 			// This should never happen.
-			have_want += '?'
+			sb.write_string('?')
 		} else {
-			have_want += c.table.type_to_str(arg_types[i]) // arg.typ)
+			sb.write_string(c.table.type_to_str(arg_types[i])) // arg.typ
 		}
 		if i < p.args.len - 1 {
-			have_want += ', '
+			sb.write_string(', ')
 		}
 	}
+	sb.write_string(')')
+	c.add_error_detail(sb.str())
 	// Actual parameters we expect
-	have_want += ')\n\twant ('
+	sb.write_string('         want (')
 	for i, param in p.params {
 		if i == 0 && p.nr_params == p.params.len - 1 {
 			// Skip receiver
 			continue
 		}
-		have_want += c.table.type_to_str(param.typ)
+		sb.write_string(c.table.type_to_str(param.typ))
 		if i < p.params.len - 1 {
-			have_want += ', '
+			sb.write_string(', ')
 		}
 	}
-	have_want += ')\n'
+	sb.write_string(')')
+	c.add_error_detail(sb.str())
 	args_plural := if p.nr_params == 1 { 'argument' } else { 'arguments' }
-	c.error('expected ${p.nr_params} ${args_plural}, but got ${p.nr_args}${have_want}',
-		p.pos)
+	c.error('expected ${p.nr_params} ${args_plural}, but got ${p.nr_args}', p.pos)
 }
 
 fn (mut c Checker) check_map_and_filter(is_map bool, elem_typ ast.Type, node ast.CallExpr) {

vlib/v/checker/tests/ambiguous_function_call.out

@@ -12,12 +12,11 @@ vlib/v/checker/tests/ambiguous_function_call.vv:7:2: error: ambiguous call to: `
     8 | }
     9 |
 vlib/v/checker/tests/ambiguous_function_call.vv:7:7: error: expected 0 arguments, but got 1
-	have (int)
-	want ()
-
     5 | fn foo2() {
     6 |     foo2 := 1
     7 |     foo2(foo2)
       |          ~~~~
     8 | }
     9 |
+Details: have (int)
+         want ()

vlib/v/checker/tests/c_fn_surplus_args.out

@@ -1,43 +1,39 @@
 vlib/v/checker/tests/c_fn_surplus_args.vv:6:7: error: expected 0 arguments, but got 1
-	have (int literal)
-	want ()
-
     4 | 
     5 | fn main() {
     6 |     C.no(1) // allowed
       |          ^
     7 |     C.y1()
     8 |     C.y1(1) // ok
+Details: have (int literal)
+         want ()
 vlib/v/checker/tests/c_fn_surplus_args.vv:7:4: error: expected 1 argument, but got 0
-	have ()
-	want (int)
-
     5 | fn main() {
     6 |     C.no(1) // allowed
     7 |     C.y1()
       |       ~~~~
     8 |     C.y1(1) // ok
     9 |     C.y1(1, 2)
+Details: have ()
+         want (int)
 vlib/v/checker/tests/c_fn_surplus_args.vv:9:10: error: expected 1 argument, but got 2
-	have (int literal, int literal)
-	want (int)
-
     7 |     C.y1()
     8 |     C.y1(1) // ok
     9 |     C.y1(1, 2)
       |             ^
    10 |     C.ret() // ok
    11 |     C.ret(1)
+Details: have (int literal, int literal)
+         want (int)
 vlib/v/checker/tests/c_fn_surplus_args.vv:11:8: error: expected 0 arguments, but got 1
-	have (int literal)
-	want ()
-
     9 |     C.y1(1, 2)
    10 |     C.ret() // ok
    11 |     C.ret(1)
       |           ^
    12 |     // avoid cgen whilst warning, later above should error
    13 |     main()
+Details: have (int literal)
+         want ()
 vlib/v/checker/tests/c_fn_surplus_args.vv:13:2: error: the `main` function cannot be called in the program
    11 |     C.ret(1)
    12 |     // avoid cgen whilst warning, later above should error
@@ -46,12 +42,11 @@ vlib/v/checker/tests/c_fn_surplus_args.vv:13:2: error: the `main` function canno
    14 |     C.af() // ok
    15 |     C.af(3)
 vlib/v/checker/tests/c_fn_surplus_args.vv:15:7: error: expected 0 arguments, but got 1
-	have (int literal)
-	want ()
-
    13 |     main()
    14 |     C.af() // ok
    15 |     C.af(3)
       |          ^
    16 | }
    17 |
+Details: have (int literal)
+         want ()

vlib/v/checker/tests/error_fn_with_0_args.out

@@ -1,8 +1,7 @@
 vlib/v/checker/tests/error_fn_with_0_args.vv:2:9: error: expected 1 argument, but got 0
-	have ()
-	want (string)
-
     1 | fn abc() ! {
     2 |     return error()
       |            ~~~~~~~
     3 | }
+Details: have ()
+         want (string)

vlib/v/checker/tests/fn_array_decompose_arg_mismatch_err_c.out

@@ -11,11 +11,10 @@ vlib/v/checker/tests/fn_array_decompose_arg_mismatch_err_c.vv:2:9: error: decomp
     3 | }
     4 |
 vlib/v/checker/tests/fn_array_decompose_arg_mismatch_err_c.vv:2:6: error: expected 0 arguments, but got 1
-	have (void)
-	want ()
-
     1 | fn main() {
     2 |     foo(...args)
       |         ~~~~~~~
     3 | }
     4 |
+Details: have (void)
+         want ()

vlib/v/checker/tests/fn_call_with_extra_parenthesis.out

@@ -1,12 +1,11 @@
 vlib/v/checker/tests/fn_call_with_extra_parenthesis.vv:5:2: error: expected 1 argument, but got 0
-	have ()
-	want (int)
-
     3 | 
     4 | fn main() {
     5 |     doit()(1)
       |     ~~~~~~
     6 | }
+Details: have ()
+         want (int)
 vlib/v/checker/tests/fn_call_with_extra_parenthesis.vv:5:9: error: unknown function: 
     3 | 
     4 | fn main() {

vlib/v/checker/tests/function_count_of_args_mismatch_err.out

@@ -1,39 +1,35 @@
 vlib/v/checker/tests/function_count_of_args_mismatch_err.vv:8:13: error: expected 1 argument, but got 3
-	have (bool, bool, int literal)
-	want (bool)
-
     6 | 
     7 | fn main() {
     8 |     test(true, false, 1)
       |                ~~~~~~~~
     9 |     test()
    10 |     test2(true, false, 1)
+Details: have (bool, bool, int literal)
+         want (bool)
 vlib/v/checker/tests/function_count_of_args_mismatch_err.vv:9:2: error: expected 1 argument, but got 0
-	have ()
-	want (bool)
-
     7 | fn main() {
     8 |     test(true, false, 1)
     9 |     test()
       |     ~~~~~~
    10 |     test2(true, false, 1)
    11 |     test2(true)
+Details: have ()
+         want (bool)
 vlib/v/checker/tests/function_count_of_args_mismatch_err.vv:10:21: error: expected 2 arguments, but got 3
-	have (bool, bool, int literal)
-	want (bool, T)
-
     8 |     test(true, false, 1)
     9 |     test()
    10 |     test2(true, false, 1)
       |                        ^
    11 |     test2(true)
    12 | }
+Details: have (bool, bool, int literal)
+         want (bool, T)
 vlib/v/checker/tests/function_count_of_args_mismatch_err.vv:11:2: error: expected 2 arguments, but got 1
-	have (bool)
-	want (bool, T)
-
     9 |     test()
    10 |     test2(true, false, 1)
    11 |     test2(true)
       |     ~~~~~~~~~~~
    12 | }
+Details: have (bool)
+         want (bool, T)

vlib/v/checker/tests/generics_fn_arguments_count_err.out

@@ -13,15 +13,14 @@ vlib/v/checker/tests/generics_fn_arguments_count_err.vv:15:18: error: expected 2
    16 |     println(ret2)
    17 |
 vlib/v/checker/tests/generics_fn_arguments_count_err.vv:15:45: error: expected 2 arguments, but got 3
-	have (int literal, int literal, string)
-	want (A, B)
-
    13 |     println(ret1)
    14 | 
    15 |     ret2 := get_name[int, int, string](11, 22, 'hello')
       |                                                ~~~~~~~
    16 |     println(ret2)
    17 |
+Details: have (int literal, int literal, string)
+         want (A, B)
 vlib/v/checker/tests/generics_fn_arguments_count_err.vv:19:22: error: expected 2 generic parameters, got 1
    17 | 
    18 |     foo := Foo{}
@@ -37,15 +36,14 @@ vlib/v/checker/tests/generics_fn_arguments_count_err.vv:22:22: error: expected 2
    23 |     println(ret4)
    24 | }
 vlib/v/checker/tests/generics_fn_arguments_count_err.vv:22:49: error: expected 2 arguments, but got 3
-	have (int literal, int literal, string)
-	want (A, B)
-
    20 |     println(ret3)
    21 | 
    22 |     ret4 := foo.get_name[int, int, string](11, 22, 'hello')
       |                                                    ~~~~~~~
    23 |     println(ret4)
    24 | }
+Details: have (int literal, int literal, string)
+         want (A, B)
 vlib/v/checker/tests/generics_fn_arguments_count_err.vv:2:12: error: no known default format for type `A`
     1 | fn get_name[A, B](a A, b B) string {
     2 |     return '${a}, ${b}'

vlib/v/checker/tests/generics_struct_field_fn_args_err.out

@@ -1,43 +1,39 @@
 vlib/v/checker/tests/generics_struct_field_fn_args_err.vv:21:20: error: expected 0 arguments, but got 1
-	have (int literal)
-	want ()
-
    19 |     }
    20 |     println(fun0.call())
    21 |     println(fun0.call(1234))
       |                       ~~~~
    22 |     println(fun0.call(1234, 5678))
    23 |
+Details: have (int literal)
+         want ()
 vlib/v/checker/tests/generics_struct_field_fn_args_err.vv:22:20: error: expected 0 arguments, but got 2
-	have (int literal, int literal)
-	want ()
-
    20 |     println(fun0.call())
    21 |     println(fun0.call(1234))
    22 |     println(fun0.call(1234, 5678))
       |                       ~~~~~~~~~~
    23 | 
    24 |     fun1 := Fun[fn (int) int]{
+Details: have (int literal, int literal)
+         want ()
 vlib/v/checker/tests/generics_struct_field_fn_args_err.vv:29:15: error: expected 1 argument, but got 0
-	have ()
-	want (int)
-
    27 | 
    28 |     println(fun1.call(42))
    29 |     println(fun1.call())
       |                  ~~~~~~
    30 |     println(fun1.call(42, 43))
    31 |
+Details: have ()
+         want (int)
 vlib/v/checker/tests/generics_struct_field_fn_args_err.vv:30:24: error: expected 1 argument, but got 2
-	have (int literal, int literal)
-	want (int)
-
    28 |     println(fun1.call(42))
    29 |     println(fun1.call())
    30 |     println(fun1.call(42, 43))
       |                           ~~
    31 | 
    32 |     println(fun1.call(true))
+Details: have (int literal, int literal)
+         want (int)
 vlib/v/checker/tests/generics_struct_field_fn_args_err.vv:32:20: error: cannot use `bool` as `int` in argument 1 to `Fun[fn (int) int].call`
    30 |     println(fun1.call(42, 43))
    31 | 

vlib/v/checker/tests/multi_return_err.out

@@ -6,35 +6,32 @@ vlib/v/checker/tests/multi_return_err.vv:18:10: error: cannot use `f64` as `int`
    19 |     my_func3(my_func2(), 'foo')
    20 |     my_func4('foo', my_func2())
 vlib/v/checker/tests/multi_return_err.vv:19:2: error: expected 3 arguments, but got 2
-	have ((int, f64), string)
-	want (int, int, string)
-
    17 | fn main() {
    18 |     my_func(my_func2())
    19 |     my_func3(my_func2(), 'foo')
       |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~
    20 |     my_func4('foo', my_func2())
    21 |     my_func(my_func5())
+Details: have ((int, f64), string)
+         want (int, int, string)
 vlib/v/checker/tests/multi_return_err.vv:20:2: error: expected 3 arguments, but got 2
-	have (string, (int, f64))
-	want (string, int, int)
-
    18 |     my_func(my_func2())
    19 |     my_func3(my_func2(), 'foo')
    20 |     my_func4('foo', my_func2())
       |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~
    21 |     my_func(my_func5())
    22 |     my_func(my_func6())
+Details: have (string, (int, f64))
+         want (string, int, int)
 vlib/v/checker/tests/multi_return_err.vv:21:2: error: expected 2 arguments, but got 1
-	have (void)
-	want (int, int)
-
    19 |     my_func3(my_func2(), 'foo')
    20 |     my_func4('foo', my_func2())
    21 |     my_func(my_func5())
       |     ~~~~~~~~~~~~~~~~~~~
    22 |     my_func(my_func6())
    23 | }
+Details: have (void)
+         want (int, int)
 vlib/v/checker/tests/multi_return_err.vv:22:10: error: expected 2 arguments, but got 3 from multi-return (int, int, int)
    20 |     my_func4('foo', my_func2())
    21 |     my_func(my_func5())

vlib/v/checker/tests/no_interface_instantiation_b.out

@@ -1,9 +1,8 @@
 vlib/v/checker/tests/no_interface_instantiation_b.vv:6:2: error: expected 1 argument, but got 0
-	have ()
-	want (Speaker)
-
     4 | 
     5 | fn main() {
     6 |     my_fn()
       |     ~~~~~~~
     7 | }
+Details: have ()
+         want (main.Speaker)

vlib/v/checker/tests/no_main_println_err.out

@@ -1,6 +1,5 @@
 vlib/v/checker/tests/no_main_println_err.vv:1:1: error: expected 1 argument, but got 0
-	have ()
-	want (string)
-
     1 | println()
       | ~~~~~~~~~
+Details: have ()
+         want (string)