compiler: add support for panic_debug with -cg

vlib/v/ast/ast.v

@@ -213,6 +213,7 @@ pub:
 	is_builtin    bool // this function is defined in builtin/strconv
 	ctdefine      string // has [if myflag] tag
 	pos           token.Position
+	file          string
 pub mut:
 	return_type   table.Type
 }

vlib/v/gen/fn.v

@@ -479,6 +479,14 @@ fn (mut g Gen) fn_call(node ast.CallExpr) {
 			}
 			g.write('))')
 		}
+	} else if g.pref.is_debug && node.name == 'panic' {
+		paline := node.pos.line_nr + 1
+		pafile := g.fn_decl.file
+		pafn := g.fn_decl.name.after('.')
+		pamod := g.fn_decl.name.all_before_last('.')
+		g.write('panic_debug($paline, tos3("$pafile"), tos3("$pamod"), tos3("$pafn"),  ')
+		g.call_args(node.args, node.expected_arg_types)
+		g.write(')')
 	} else {
 		g.write('${name}(')
 		g.call_args(node.args, node.expected_arg_types)

vlib/v/parser/fn.v

@@ -255,6 +255,7 @@ fn (mut p Parser) fn_decl() ast.FnDecl {
 		is_js: is_js
 		no_body: no_body
 		pos: start_pos.extend(end_pos)
+		file: p.file_name
 		is_builtin: p.builtin_mod || p.mod in util.builtin_module_parts
 		ctdefine: ctdefine
 	}
@@ -305,6 +306,7 @@ fn (mut p Parser) anon_fn() ast.AnonFn {
 			is_anon: true
 			no_body: no_body
 			pos: pos
+			file: p.file_name
 		}
 		typ: typ
 	}

vlib/v/parser/parser.v

@@ -106,6 +106,7 @@ pub fn parse_file(path string, b_table &table.Table, comments_mode scanner.Comme
 			if p.pref.is_script && !p.pref.is_test && p.mod == 'main' && !have_fn_main(stmts) {
 				stmts << ast.FnDecl {
 					name: 'main'
+					file: p.file_name
 					return_type: table.void_type
 				}
 			}

vlib/v/parser/struct.v

@@ -286,6 +286,7 @@ fn (mut p Parser) interface_decl() ast.InterfaceDecl {
 		mut method := ast.FnDecl{
 			name: name
 			args: args
+			file: p.file_name
 			return_type: table.void_type
 		}
 		if p.tok.kind.is_start_of_type() && p.tok.line_nr == line_nr {