all: volatile globals

vlib/v/ast/ast.v

@@ -663,6 +663,7 @@ pub:
 	pos         token.Pos
 	typ_pos     token.Pos
 	is_markused bool // an explict `[markused]` tag; the global will NOT be removed by `-skip-unused`
+	is_volatile bool
 pub mut:
 	expr     Expr
 	typ      Type

vlib/v/gen/c/cgen.v

@@ -4417,7 +4417,8 @@ fn (mut g Gen) global_decl(node ast.GlobalDecl) {
 			g.definitions.writeln('$fn_type_name = ${g.table.sym(field.typ).name}; // global2')
 			continue
 		}
-		g.definitions.write_string('$visibility_kw$styp $attributes $field.name')
+		modifier := if field.is_volatile { ' volatile ' } else { '' }
+		g.definitions.write_string('$visibility_kw$modifier$styp $attributes $field.name')
 		if field.has_expr || cinit {
 			if g.pref.translated {
 				g.definitions.write_string(' = ${g.expr_string(field.expr)}')

vlib/v/parser/parser.v

@@ -3364,6 +3364,10 @@ fn (mut p Parser) global_decl() ast.GlobalDecl {
 	mut comments := []ast.Comment{}
 	for {
 		comments = p.eat_comments()
+		is_volatile := p.tok.kind == .key_volatile
+		if is_volatile {
+			p.next()
+		}
 		if is_block && p.tok.kind == .eof {
 			p.error('unexpected eof, expecting `)`')
 			return ast.GlobalDecl{}
@@ -3416,6 +3420,7 @@ fn (mut p Parser) global_decl() ast.GlobalDecl {
 			typ: typ
 			comments: comments
 			is_markused: is_markused
+			is_volatile: is_volatile
 		}
 		fields << field
 		p.table.global_scope.register(field)