parser,checker: support `[generated] module xyz` (turns off notices). Use it for `infix.v`.

vlib/v/ast/ast.v

@@ -668,6 +668,7 @@ pub:
 	mod          Module // the module of the source file (from `module xyz` at the top)
 	global_scope &Scope
 	is_test      bool // true for _test.v files
+	is_generated bool // true for `[generated] module xyz` files; turn off notices
 pub mut:
 	path             string // absolute path of the source file - '/projects/v/file.v'
 	path_base        string // file name - 'file.v' (useful for tracing)

vlib/v/checker/check_types.v

@@ -5,7 +5,6 @@ module checker
 
 import v.ast
 import v.token
-import os
 
 // TODO: promote(), check_types(), symmetric_check() and check() overlap - should be rearranged
 pub fn (mut c Checker) check_types(got ast.Type, expected ast.Type) bool {
@@ -260,10 +259,6 @@ pub fn (mut c Checker) check_matching_function_symbols(got_type_sym &ast.TypeSym
 	return true
 }
 
-// TODO: remove this exception, by using a more general mechanism for opting out
-// generated code, from warnings/notices, that are targeted at humans:
-const infix_v_exception = os.join_path('vlib', 'v', 'eval', 'infix.v')
-
 fn (mut c Checker) check_shift(mut node ast.InfixExpr, left_type ast.Type, right_type ast.Type) ast.Type {
 	if !left_type.is_int() {
 		left_sym := c.table.get_type_symbol(left_type)
@@ -323,7 +318,7 @@ fn (mut c Checker) check_shift(mut node ast.InfixExpr, left_type ast.Type, right
 			left_sym_final := c.table.get_final_type_symbol(left_type)
 			left_type_final := ast.Type(left_sym_final.idx)
 			if node.op == .left_shift && left_type_final.is_signed() && !(c.inside_unsafe
-				&& c.file.path.ends_with(checker.infix_v_exception)) {
+				&& c.is_generated) {
 				c.note('shifting a value from a signed type `$left_sym_final.name` can change the sign',
 					node.left.position())
 			}

vlib/v/checker/checker.v

@@ -73,6 +73,7 @@ pub mut:
 	scope_returns  bool
 	mod            string // current module name
 	is_builtin_mod bool   // true inside the 'builtin', 'os' or 'strconv' modules; TODO: remove the need for special casing this
+	is_generated   bool   // true for `[generated] module xyz` .v files
 	inside_unsafe  bool   // true inside `unsafe {}` blocks
 	inside_const   bool   // true inside `const ( ... )` blocks
 	inside_anon_fn bool   // true inside `fn() { ... }()`
@@ -248,6 +249,7 @@ pub fn (mut c Checker) change_current_file(file &ast.File) {
 	c.file = unsafe { file }
 	c.vmod_file_content = ''
 	c.mod = file.mod.name
+	c.is_generated = file.is_generated
 }
 
 pub fn (mut c Checker) check_files(ast_files []&ast.File) {
@@ -4707,6 +4709,9 @@ pub fn (mut c Checker) note(message string, pos token.Position) {
 		c.should_abort = true
 		return
 	}
+	if c.is_generated {
+		return
+	}
 	mut details := ''
 	if c.error_details.len > 0 {
 		details = c.error_details.join('\n')

vlib/v/eval/gen/infix_gen.v

@@ -5,7 +5,8 @@ import strings
 import os
 
 const (
-	header = 'module eval
+	header = '[generated]
+module eval
 import v.token
 import v.ast
 fn(e Eval)infix_expr(left Object,right Object,op token.Kind,expecting ast.Type)Object{match op{'

vlib/v/eval/infix.v

@@ -1,3 +1,4 @@
+[generated]
 module eval
 
 import v.token

vlib/v/parser/parser.v

@@ -51,6 +51,7 @@ mut:
 	mod                 string     // current module name
 	is_manualfree       bool       // true when `[manualfree] module abc`, makes *all* fns in the current .v file, opt out of autofree
 	has_globals         bool       // `[has_globals] module abc` - allow globals declarations, even without -enable-globals, in that single .v file __only__
+	is_generated        bool       // `[generated] module abc` - turn off compiler notices for that single .v file __only__.
 	attrs               []ast.Attr // attributes before next decl stmt
 	expr_mod            string     // for constructing full type names in parse_type()
 	scope               &ast.Scope
@@ -310,6 +311,7 @@ pub fn (mut p Parser) parse() &ast.File {
 		path: p.file_name
 		path_base: p.file_base
 		is_test: p.inside_test_file
+		is_generated: p.is_generated
 		nr_lines: p.scanner.line_nr
 		nr_bytes: p.scanner.text.len
 		mod: module_decl
@@ -1760,6 +1762,9 @@ pub fn (mut p Parser) note_with_pos(s string, pos token.Position) {
 	if p.pref.skip_warnings {
 		return
 	}
+	if p.is_generated {
+		return
+	}
 	if p.pref.output_mode == .stdout && !p.pref.check_only {
 		ferror := util.formatted_error('notice:', s, p.file_name, pos)
 		eprintln(ferror)
@@ -2844,6 +2849,9 @@ fn (mut p Parser) module_decl() ast.Module {
 				'manualfree' {
 					p.is_manualfree = true
 				}
+				'generated' {
+					p.is_generated = true
+				}
 				'has_globals' {
 					if p.inside_vlib_file {
 						p.has_globals = true