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// Copyright 2012-2013 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
/*!
Lint mode to detect cases where we call non-Rust fns, which do not
have a stack growth check, from locations not annotated to request
large stacks.
*/
use middle::lint;
use middle::ty;
use syntax::ast;
use syntax::ast_map;
use syntax::attr;
use syntax::codemap::Span;
use syntax::visit;
use syntax::visit::Visitor;
use util::ppaux::Repr;
#[deriving(Clone)]
struct Context {
safe_stack: bool
}
struct StackCheckVisitor {
tcx: ty::ctxt,
}
impl Visitor<Context> for StackCheckVisitor {
fn visit_item(&mut self, i:@ast::item, e:Context) {
stack_check_item(self, i, e);
}
fn visit_fn(&mut self, fk:&visit::fn_kind, fd:&ast::fn_decl,
b:&ast::Block, s:Span, n:ast::NodeId, e:Context) {
stack_check_fn(self, fk, fd, b, s, n, e);
}
fn visit_expr(&mut self, ex:@ast::Expr, e:Context) {
stack_check_expr(self, ex, e);
}
}
pub fn stack_check_crate(tcx: ty::ctxt,
crate: &ast::Crate) {
let new_cx = Context { safe_stack: false };
let mut visitor = StackCheckVisitor { tcx: tcx };
visit::walk_crate(&mut visitor, crate, new_cx);
}
fn stack_check_item(v: &mut StackCheckVisitor,
item: @ast::item,
in_cx: Context) {
match item.node {
ast::item_fn(_, ast::extern_fn, _, _, _) => {
// an extern fn is already being called from C code...
let new_cx = Context {safe_stack: true};
visit::walk_item(v, item, new_cx);
}
ast::item_fn(*) => {
let safe_stack = fixed_stack_segment(item.attrs);
let new_cx = Context {safe_stack: safe_stack};
visit::walk_item(v, item, new_cx);
}
ast::item_impl(_, _, _, ref methods) => {
// visit_method() would make this nicer
for &method in methods.iter() {
let safe_stack = fixed_stack_segment(method.attrs);
let new_cx = Context {safe_stack: safe_stack};
visit::walk_method_helper(v, method, new_cx);
}
}
ast::item_trait(_, _, ref methods) => {
for method in methods.iter() {
match *method {
ast::provided(@ref method) => {
let safe_stack = fixed_stack_segment(method.attrs);
let new_cx = Context {safe_stack: safe_stack};
visit::walk_method_helper(v, method, new_cx);
}
ast::required(*) => ()
}
}
}
_ => {
visit::walk_item(v, item, in_cx);
}
}
fn fixed_stack_segment(attrs: &[ast::Attribute]) -> bool {
attr::contains_name(attrs, "fixed_stack_segment")
}
}
fn stack_check_fn<'a>(v: &mut StackCheckVisitor,
fk: &visit::fn_kind,
decl: &ast::fn_decl,
body: &ast::Block,
sp: Span,
id: ast::NodeId,
in_cx: Context) {
let safe_stack = match *fk {
visit::fk_method(*) | visit::fk_item_fn(*) => {
in_cx.safe_stack // see stack_check_item above
}
visit::fk_anon(*) | visit::fk_fn_block => {
match ty::get(ty::node_id_to_type(v.tcx, id)).sty {
ty::ty_bare_fn(*) |
ty::ty_closure(ty::ClosureTy {sigil: ast::OwnedSigil, _}) => {
false
}
_ => {
in_cx.safe_stack
}
}
}
};
let new_cx = Context {safe_stack: safe_stack};
debug!("stack_check_fn(safe_stack=%b, id=%?)", safe_stack, id);
visit::walk_fn(v, fk, decl, body, sp, id, new_cx);
}
fn stack_check_expr<'a>(v: &mut StackCheckVisitor,
expr: @ast::Expr,
cx: Context) {
debug!("stack_check_expr(safe_stack=%b, expr=%s)",
cx.safe_stack, expr.repr(v.tcx));
if !cx.safe_stack {
match expr.node {
ast::ExprCall(callee, _, _) => {
let callee_ty = ty::expr_ty(v.tcx, callee);
debug!("callee_ty=%s", callee_ty.repr(v.tcx));
match ty::get(callee_ty).sty {
ty::ty_bare_fn(ref fty) => {
if !fty.abis.is_rust() && !fty.abis.is_intrinsic() {
call_to_extern_fn(v, callee);
}
}
_ => {}
}
}
_ => {}
}
}
visit::walk_expr(v, expr, cx);
}
fn call_to_extern_fn(v: &mut StackCheckVisitor, callee: @ast::Expr) {
// Permit direct calls to extern fns that are annotated with
// #[rust_stack]. This is naturally a horrible pain to achieve.
match callee.node {
ast::ExprPath(*) => {
match v.tcx.def_map.find(&callee.id) {
Some(&ast::DefFn(id, _)) if id.crate == ast::LOCAL_CRATE => {
match v.tcx.items.find(&id.node) {
Some(&ast_map::node_foreign_item(item, _, _, _)) => {
if attr::contains_name(item.attrs, "rust_stack") {
return;
}
}
_ => {}
}
}
_ => {}
}
}
_ => {}
}
v.tcx.sess.add_lint(lint::cstack,
callee.id,
callee.span,
fmt!("invoking non-Rust fn in fn without \
#[fixed_stack_segment]"));
}
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