parser: make script mode errors more informative, when a top level declaration is encountered, after script mode had already started

vlib/v/parser/expr.v

@@ -9,6 +9,9 @@ import v.token
 
 pub fn (mut p Parser) expr(precedence int) ast.Expr {
 	return p.check_expr(precedence) or {
+		if token.is_decl(p.tok.kind) && p.disallow_declarations_in_script_mode() {
+			return ast.empty_expr()
+		}
 		p.error_with_pos('invalid expression: unexpected $p.tok', p.tok.pos())
 	}
 }

vlib/v/parser/fn.v

@@ -673,10 +673,10 @@ fn (mut p Parser) fn_receiver(mut params []ast.Param, mut rec ReceiverParsingInf
 fn (mut p Parser) anon_fn() ast.AnonFn {
 	pos := p.tok.pos()
 	p.check(.key_fn)
-	if p.pref.is_script && p.tok.kind == .name {
+	if p.tok.kind == .name {
-		p.error_with_pos('function declarations in script mode should be before all script statements',
+		if p.disallow_declarations_in_script_mode() {
-			p.tok.pos())
+			return ast.AnonFn{}
-		return ast.AnonFn{}
+		}
 	}
 	old_inside_defer := p.inside_defer
 	p.inside_defer = false

vlib/v/parser/parser.v

@@ -93,6 +93,8 @@ mut:
 	codegen_text              string
 	struct_init_generic_types []ast.Type
 	if_cond_comments          []ast.Comment
+	script_mode               bool
+	script_mode_start_token   token.Token
 }
 
 __global codegen_files = []&ast.File{}
@@ -685,12 +687,17 @@ pub fn (mut p Parser) top_stmt() ast.Stmt {
 			else {
 				p.inside_fn = true
 				if p.pref.is_script && !p.pref.is_test {
+					p.script_mode = true
+					p.script_mode_start_token = p.tok
+
 					p.open_scope()
 					mut stmts := []ast.Stmt{}
 					for p.tok.kind != .eof {
 						stmts << p.stmt(false)
 					}
 					p.close_scope()
+
+					p.script_mode = false
 					return ast.FnDecl{
 						name: 'main.main'
 						short_name: 'main'
@@ -3276,6 +3283,9 @@ fn (mut p Parser) const_decl() ast.ConstDecl {
 		p.next()
 	}
 	const_pos := p.tok.pos()
+	if p.disallow_declarations_in_script_mode() {
+		return ast.ConstDecl{}
+	}
 	p.check(.key_const)
 	is_block := p.tok.kind == .lpar
 	if is_block {
@@ -3390,6 +3400,9 @@ fn (mut p Parser) global_decl() ast.GlobalDecl {
 	}
 	start_pos := p.tok.pos()
 	p.check(.key_global)
+	if p.disallow_declarations_in_script_mode() {
+		return ast.GlobalDecl{}
+	}
 	is_block := p.tok.kind == .lpar
 	if is_block {
 		p.next() // (
@@ -3485,6 +3498,9 @@ fn (mut p Parser) enum_decl() ast.EnumDecl {
 	}
 	p.check(.key_enum)
 	end_pos := p.tok.pos()
+	if p.disallow_declarations_in_script_mode() {
+		return ast.EnumDecl{}
+	}
 	enum_name := p.check_name()
 	if enum_name.len == 1 {
 		p.error_with_pos('single letter capital names are reserved for generic template types.',
@@ -3597,6 +3613,9 @@ fn (mut p Parser) type_decl() ast.TypeDecl {
 	end_pos := p.tok.pos()
 	decl_pos := start_pos.extend(end_pos)
 	name_pos := p.tok.pos()
+	if p.disallow_declarations_in_script_mode() {
+		return ast.SumTypeDecl{}
+	}
 	name := p.check_name()
 	if name.len == 1 && name[0].is_capital() {
 		p.error_with_pos('single letter capital names are reserved for generic template types.',
@@ -3889,6 +3908,15 @@ fn (mut p Parser) unsafe_stmt() ast.Stmt {
 	}
 }
 
+fn (mut p Parser) disallow_declarations_in_script_mode() bool {
+	if p.script_mode {
+		p.note_with_pos('script mode started here', p.script_mode_start_token.pos())
+		p.error_with_pos('all definitions must occur before code in script mode', p.tok.pos())
+		return true
+	}
+	return false
+}
+
 fn (mut p Parser) trace(fbase string, message string) {
 	if p.file_base == fbase {
 		println('> p.trace | ${fbase:-10s} | $message')

vlib/v/parser/struct.v

@@ -36,6 +36,9 @@ fn (mut p Parser) struct_decl() ast.StructDecl {
 	}
 	name_pos := p.tok.pos()
 	p.check_for_impure_v(language, name_pos)
+	if p.disallow_declarations_in_script_mode() {
+		return ast.StructDecl{}
+	}
 	mut name := p.check_name()
 	// defer {
 	// if name.contains('App') {
@@ -471,6 +474,9 @@ fn (mut p Parser) interface_decl() ast.InterfaceDecl {
 	}
 	name_pos := p.tok.pos()
 	p.check_for_impure_v(language, name_pos)
+	if p.disallow_declarations_in_script_mode() {
+		return ast.InterfaceDecl{}
+	}
 	modless_name := p.check_name()
 	if modless_name == 'IError' && p.mod != 'builtin' {
 		p.error_with_pos('cannot register interface `IError`, it is builtin interface type',

vlib/v/parser/tests/invalid_enum_decl_script_err.out

@@ -0,0 +1,12 @@
+vlib/v/parser/tests/invalid_enum_decl_script_err.vv:1:1: notice: script mode started here
+    1 | mynum := 10
+      | ~~~~~
+    2 | 
+    3 | enum MyEnum {
+vlib/v/parser/tests/invalid_enum_decl_script_err.vv:3:1: error: all definitions must occur before code in script mode
+    1 | mynum := 10
+    2 | 
+    3 | enum MyEnum {
+      | ~~~~
+    4 |     aa
+    5 |     bb

vlib/v/parser/tests/invalid_enum_decl_script_err.vv

@@ -0,0 +1,7 @@
+mynum := 10
+
+enum MyEnum {
+	aa
+	bb
+	cc
+}

vlib/v/parser/tests/invalid_fn_decl_script_err.out

@@ -1,7 +1,12 @@
-vlib/v/parser/tests/invalid_fn_decl_script_err.vv:3:4: error: function declarations in script mode should be before all script statements
+vlib/v/parser/tests/invalid_fn_decl_script_err.vv:1:1: notice: script mode started here
+    1 | mynum := 10
+      | ~~~~~
+    2 | 
+    3 | fn my_function() {
+vlib/v/parser/tests/invalid_fn_decl_script_err.vv:3:4: error: all definitions must occur before code in script mode
     1 | mynum := 10
     2 | 
-    3 | fn main() {
+    3 | fn my_function() {
-      |    ~~~~
+      |    ~~~~~~~~~~~
     4 |     println(mynum)
     5 | }

vlib/v/parser/tests/invalid_fn_decl_script_err.vv

@@ -1,5 +1,5 @@
 mynum := 10
 
-fn main() {
+fn my_function() {
 	println(mynum)
 }

vlib/v/parser/tests/invalid_interface_decl_script_err.out

@@ -0,0 +1,11 @@
+vlib/v/parser/tests/invalid_interface_decl_script_err.vv:1:1: notice: script mode started here
+    1 | mynum := 10
+      | ~~~~~
+    2 | 
+    3 | interface IUniversal {
+vlib/v/parser/tests/invalid_interface_decl_script_err.vv:3:1: error: all definitions must occur before code in script mode
+    1 | mynum := 10
+    2 | 
+    3 | interface IUniversal {
+      | ~~~~~~~~~
+    4 | }

vlib/v/parser/tests/invalid_interface_decl_script_err.vv

@@ -0,0 +1,4 @@
+mynum := 10
+
+interface IUniversal {
+}

vlib/v/parser/tests/invalid_struct_decl_script_err.out

@@ -0,0 +1,12 @@
+vlib/v/parser/tests/invalid_struct_decl_script_err.vv:1:1: notice: script mode started here
+    1 | mynum := 10
+      | ~~~~~
+    2 | 
+    3 | struct Abc {
+vlib/v/parser/tests/invalid_struct_decl_script_err.vv:3:1: error: all definitions must occur before code in script mode
+    1 | mynum := 10
+    2 | 
+    3 | struct Abc {
+      | ~~~~~~
+    4 |     x int
+    5 | }

vlib/v/parser/tests/invalid_struct_decl_script_err.vv

@@ -0,0 +1,5 @@
+mynum := 10
+
+struct Abc {
+	x int
+}