Auto merge of #105919 - uweigand:s390x-stack-overflow, r=Nilstrieb

Fix stack overflow in recursive AST walk in early lint

The src/test/ui/issues/issue-74564-if-expr-stack-overflow.rs test case added to verify https://github.com/rust-lang/rust/issues/74564 still crashes with a stack overflow on s390x-ibm-linux.

Symptom is a very deep recursion in compiler/rustc_lint/src/early.rs:
    fn visit_expr(&mut self, e: &'a ast::Expr) {
        self.with_lint_attrs(e.id, &e.attrs, |cx| {
            lint_callback!(cx, check_expr, e);
            ast_visit::walk_expr(cx, e);
        })
    }
(where walk_expr recursively calls back into visit_expr).  The crash happens at a nesting depth of over 17000 stack frames when using the default 8 MB stack size on s390x.

This patch fixes the problem by adding a ensure_sufficient_stack call to the with_lint_attrs routine (which also should take care of all the other mutually recursive visitors here).

Fixes part of https://github.com/rust-lang/rust/issues/105383.
This commit is contained in:
bors 2023-01-11 08:50:38 +00:00
commit 8ecaad85f6

View file

@ -19,6 +19,7 @@
use rustc_ast::ptr::P;
use rustc_ast::visit::{self as ast_visit, Visitor};
use rustc_ast::{self as ast, walk_list, HasAttrs};
use rustc_data_structures::stack::ensure_sufficient_stack;
use rustc_middle::ty::RegisteredTools;
use rustc_session::lint::{BufferedEarlyLint, LintBuffer, LintPass};
use rustc_session::Session;
@ -71,7 +72,7 @@ fn with_lint_attrs<F>(&mut self, id: ast::NodeId, attrs: &'a [ast::Attribute], f
self.inlined_check_id(id);
debug!("early context: enter_attrs({:?})", attrs);
lint_callback!(self, enter_lint_attrs, attrs);
f(self);
ensure_sufficient_stack(|| f(self));
debug!("early context: exit_attrs({:?})", attrs);
lint_callback!(self, exit_lint_attrs, attrs);
self.context.builder.pop(push);