checker: add check for strict .str() method signature

vlib/v/ast/str.v

@@ -24,7 +24,7 @@ pub fn (node &FnDecl) modname() string {
 
 // These methods are used only by vfmt, vdoc, and for debugging.
 
-pub fn (node &FnDecl) str(t &table.Table) string {
+pub fn (node &FnDecl) stringify(t &table.Table) string {
 	mut f := strings.new_builder(30)
 	if node.is_pub {
 		f.write('pub ')

vlib/v/checker/checker.v

@@ -2950,6 +2950,16 @@ fn (mut c Checker) fn_decl(node ast.FnDecl) {
 			}
 		}
 	}
+
+	if node.language == .v && node.is_method && node.name == 'str' {
+		if node.return_type != table.string_type {
+			c.error('.str() methods should return `string`', node.pos)
+		}
+		if node.args.len != 1 {
+			c.error('.str() methods should have 0 arguments', node.pos)
+		}
+	}
+
 	c.expected_type = table.void_type
 	c.cur_fn = &node
 	c.stmts(node.stmts)

vlib/v/checker/tests/str_method_0_arguments.out

@@ -0,0 +1,7 @@
+vlib/v/checker/tests/str_method_0_arguments.v:5:1: error: .str() methods should have 0 arguments 
+    3 | }
+    4 | 
+    5 | fn (z Zzz) str(x int) string {
+      | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+    6 |     return 'z: $z.x'
+    7 | }

vlib/v/checker/tests/str_method_0_arguments.vv

@@ -0,0 +1,11 @@
+struct Zzz {
+	x int
+}
+
+fn (z Zzz) str(x int) string {
+    return 'z: $z.x'
+}
+
+fn main() {
+	println(Zzz{123})
+}

vlib/v/checker/tests/str_method_return_string.out

@@ -0,0 +1,7 @@
+vlib/v/checker/tests/str_method_return_string.v:5:1: error: .str() methods should return `string` 
+    3 | }
+    4 | 
+    5 | fn (z Zzz) str(x int) int {
+      | ~~~~~~~~~~~~~~~~~~~~~~~~~
+    6 |     return z.x
+    7 | }

vlib/v/checker/tests/str_method_return_string.vv

@@ -0,0 +1,11 @@
+struct Zzz {
+	x int
+}
+
+fn (z Zzz) str(x int) int {
+	return z.x
+}
+
+fn main() {
+	println(Zzz{123})
+}

vlib/v/doc/doc.v

@@ -119,7 +119,7 @@ pub fn (mut d Doc) get_signature(stmt ast.Stmt, file &ast.File) string {
 			return 'module $stmt.name'
 		}
 		ast.FnDecl {
-			return stmt.str(d.table).replace(d.fmt.cur_mod + '.', '')
+			return stmt.stringify(d.table).replace(d.fmt.cur_mod + '.', '')
 		}
 		else {
 			d.fmt.out = strings.new_builder(1000)

vlib/v/fmt/fmt.v

@@ -421,7 +421,7 @@ pub fn (mut f Fmt) stmt(node ast.Stmt) {
 			f.writeln('interface $it.name {')
 			for method in it.methods {
 				f.write('\t')
-				f.writeln(method.str(f.table).after('fn '))
+				f.writeln(method.stringify(f.table).after('fn '))
 			}
 			f.writeln('}\n')
 		}
@@ -1134,7 +1134,7 @@ pub fn (mut f Fmt) comments(some_comments []ast.Comment, remove_last_new_line bo
 pub fn (mut f Fmt) fn_decl(node ast.FnDecl) {
 	// println('$it.name find_comment($it.pos.line_nr)')
 	// f.find_comment(it.pos.line_nr)
-	s := node.str(f.table)
+	s := node.stringify(f.table)
 	f.write(s.replace(f.cur_mod + '.', '')) // `Expr` instead of `ast.Expr` in mod ast
 	if node.language == .v {
 		f.writeln(' {')

vlib/v/gen/cgen.v

@@ -3232,9 +3232,9 @@ fn (mut g Gen) gen_expr_to_string(expr ast.Expr, etype table.Type) ?bool {
 		g.expr(expr)
 		if sym.kind == .struct_ && !sym_has_str_method {
 			if is_p {
-				g.write('),0))')
+				g.write(')))')
 			} else {
-				g.write(',0)')
+				g.write(')')
 			}
 		} else {
 			if is_p {
@@ -4062,8 +4062,12 @@ fn (mut g Gen) gen_str_for_struct(info table.Struct, styp, str_fn_name string) {
 			fnames2strfunc[field_styp] = field_fn_name
 		}
 	}
-	g.type_definitions.writeln('string ${str_fn_name}($styp x, int indent_count); // auto')
+	// _str() functions should have a single argument, the indenting ones take 2:
-	g.auto_str_funcs.writeln('string ${str_fn_name}($styp x, int indent_count) {')
+	g.type_definitions.writeln('string ${str_fn_name}($styp x); // auto')
+	g.auto_str_funcs.writeln('string ${str_fn_name}($styp x) { return indent_${str_fn_name}(x,0);}')
+	//
+	g.type_definitions.writeln('string indent_${str_fn_name}($styp x, int indent_count); // auto')
+	g.auto_str_funcs.writeln('string indent_${str_fn_name}($styp x, int indent_count) {')
 	mut clean_struct_v_type_name := styp.replace('__', '.')
 	if styp.ends_with('*') {
 		deref_typ := styp.replace('*', '')
@@ -4090,7 +4094,6 @@ fn (mut g Gen) gen_str_for_struct(info table.Struct, styp, str_fn_name string) {
 		for i, field in info.fields {
 			sym := g.table.get_type_symbol(field.typ)
 			has_custom_str := sym.has_method('str')
-			second_str_param := if has_custom_str { '' } else { ', indent_count + 1' }
 			mut field_styp := g.typ(field.typ)
 			if field_styp.ends_with('*') {
 				field_styp = field_styp.replace('*', '')
@@ -4101,7 +4104,11 @@ fn (mut g Gen) gen_str_for_struct(info table.Struct, styp, str_fn_name string) {
 				g.auto_str_funcs.write('${field_styp_fn_name}( it->${c_name(field.name)} ) ')
 			} else if sym.kind == .struct_ {
 				g.auto_str_funcs.write('indents, ')
-				g.auto_str_funcs.write('${field_styp_fn_name}( it->${c_name(field.name)}$second_str_param ) ')
+				if has_custom_str {
+					g.auto_str_funcs.write('${field_styp_fn_name}( it->${c_name(field.name)} ) ')
+				}else{
+					g.auto_str_funcs.write('indent_${field_styp_fn_name}( it->${c_name(field.name)}, indent_count + 1 ) ')
+				}
 			} else if sym.kind in [.array, .array_fixed, .map] {
 				g.auto_str_funcs.write('indents, ')
 				g.auto_str_funcs.write('${field_styp_fn_name}( it->${c_name(field.name)}) ')
@@ -4145,9 +4152,9 @@ fn (mut g Gen) gen_str_for_array(info table.Array, styp, str_fn_name string) {
 	g.auto_str_funcs.writeln('\t\t$field_styp it = (*($field_styp*)array_get(a, i));')
 	if sym.kind == .struct_ && !sym_has_str_method {
 		if is_elem_ptr {
-			g.auto_str_funcs.writeln('\t\tstring x = ${elem_str_fn_name}(*it,0);')
+			g.auto_str_funcs.writeln('\t\tstring x = ${elem_str_fn_name}(*it);')
 		} else {
-			g.auto_str_funcs.writeln('\t\tstring x = ${elem_str_fn_name}(it,0);')
+			g.auto_str_funcs.writeln('\t\tstring x = ${elem_str_fn_name}(it);')
 		}
 	} else if sym.kind in [.f32, .f64] {
 		g.auto_str_funcs.writeln('\t\tstring x = _STR("%g", 1, it);')
@@ -4201,7 +4208,7 @@ fn (mut g Gen) gen_str_for_array_fixed(info table.ArrayFixed, styp, str_fn_name
 	g.auto_str_funcs.writeln('\tstrings__Builder_write(&sb, tos_lit("["));')
 	g.auto_str_funcs.writeln('\tfor (int i = 0; i < $info.size; ++i) {')
 	if sym.kind == .struct_ && !sym_has_str_method {
-		g.auto_str_funcs.writeln('\t\tstrings__Builder_write(&sb, ${elem_str_fn_name}(a[i],0));')
+		g.auto_str_funcs.writeln('\t\tstrings__Builder_write(&sb, ${elem_str_fn_name}(a[i]));')
 	} else if sym.kind in [.f32, .f64] {
 		g.auto_str_funcs.writeln('\t\tstrings__Builder_write(&sb, _STR("%g", 1, a[i]));')
 	} else if sym.kind == .string {
@@ -4252,7 +4259,7 @@ fn (mut g Gen) gen_str_for_map(info table.Map, styp, str_fn_name string) {
 	if val_sym.kind == .string {
 		g.auto_str_funcs.writeln('\t\tstrings__Builder_write(&sb, _STR("\'%.*s\\000\'", 2, it));')
 	} else if val_sym.kind == .struct_ && !val_sym.has_method('str') {
-		g.auto_str_funcs.writeln('\t\tstrings__Builder_write(&sb, ${elem_str_fn_name}(it,0));')
+		g.auto_str_funcs.writeln('\t\tstrings__Builder_write(&sb, ${elem_str_fn_name}(it));')
 	} else if val_sym.kind in [.f32, .f64] {
 		g.auto_str_funcs.writeln('\t\tstrings__Builder_write(&sb, _STR("%g", 1, it));')
 	} else {
@@ -4273,12 +4280,7 @@ fn (mut g Gen) gen_str_for_varg(styp, str_fn_name string, has_str_method bool) {
 	g.auto_str_funcs.writeln('\tstrings__Builder sb = strings__new_builder(it.len);')
 	g.auto_str_funcs.writeln('\tstrings__Builder_write(&sb, tos_lit("["));')
 	g.auto_str_funcs.writeln('\tfor(int i=0; i<it.len; ++i) {')
-	if has_str_method {
+	g.auto_str_funcs.writeln('\t\tstrings__Builder_write(&sb, ${str_fn_name}(it.args[i]));')
-		g.auto_str_funcs.writeln('\t\tstrings__Builder_write(&sb, ${str_fn_name}(it.args[i]));')
-	} else {
-		// autogenerated str methods take the indent level as a second argument:
-		g.auto_str_funcs.writeln('\t\tstrings__Builder_write(&sb, ${str_fn_name}(it.args[i], 0));')
-	}
 	g.auto_str_funcs.writeln('\t\tif (i < it.len-1) {')
 	g.auto_str_funcs.writeln('\t\t\tstrings__Builder_write(&sb, tos_lit(", "));')
 	g.auto_str_funcs.writeln('\t\t}')
@@ -4313,7 +4315,7 @@ fn (mut g Gen) gen_str_for_multi_return(info table.MultiReturn, styp, str_fn_nam
 			arg_str_fn_name = styp_to_str_fn_name(field_styp)
 		}
 		if sym.kind == .struct_ && !sym_has_str_method {
-			g.auto_str_funcs.writeln('\tstrings__Builder_write(&sb, ${str_fn_name}(a.arg$i,0));')
+			g.auto_str_funcs.writeln('\tstrings__Builder_write(&sb, ${str_fn_name}(a.arg$i));')
 		} else if sym.kind in [.f32, .f64] {
 			g.auto_str_funcs.writeln('\tstrings__Builder_write(&sb, _STR("%g", 1, a.arg$i));')
 		} else if sym.kind == .string {

vlib/v/gen/fn.v

@@ -515,10 +515,6 @@ fn (mut g Gen) fn_call(node ast.CallExpr) {
 					g.write('*')
 				}
 				g.expr(expr)
-				if !typ.has_flag(.variadic) && sym.kind == .struct_ &&
-					styp != 'ptr' && !sym.has_method('str') {
-					g.write(', 0') // trailing 0 is initial struct indent count
-				}
 			}
 			g.write('))')
 		}