auto merge of #17678 : fhahn/rust/issue-17628-infinite-recursion, r=alexcrichton

This is a patch for #17628, thanks to @kmcallister for your helpful hints!

Author: bors

src/librustc/driver/driver.rs

@@ -291,6 +291,7 @@ pub fn phase_2_configure_and_expand(sess: &Session,
                 crate_name: crate_name.to_string(),
                 deriving_hash_type_parameter: sess.features.borrow().default_type_params,
                 enable_quotes: sess.features.borrow().quote,
+                recursion_limit: sess.recursion_limit.get(),
             };
             let ret = syntax::ext::expand::expand_crate(&sess.parse_sess,
                                               cfg,

src/libsyntax/ext/base.rs

@@ -463,6 +463,7 @@ pub struct ExtCtxt<'a> {
     pub exported_macros: Vec<P<ast::Item>>,
 
     pub syntax_env: SyntaxEnv,
+    pub recursion_count: uint,
 }
 
 impl<'a> ExtCtxt<'a> {
@@ -478,6 +479,7 @@ impl<'a> ExtCtxt<'a> {
             trace_mac: false,
             exported_macros: Vec::new(),
             syntax_env: env,
+            recursion_count: 0,
         }
     }
 
@@ -552,6 +554,13 @@ impl<'a> ExtCtxt<'a> {
         return v;
     }
     pub fn bt_push(&mut self, ei: ExpnInfo) {
+        self.recursion_count += 1;
+        if self.recursion_count > self.ecfg.recursion_limit {
+            self.span_fatal(ei.call_site,
+                            format!("Recursion limit reached while expanding the macro `{}`",
+                                    ei.callee.name).as_slice());
+        }
+
         let mut call_site = ei.call_site;
         call_site.expn_id = self.backtrace;
         self.backtrace = self.codemap().record_expansion(ExpnInfo {
@@ -563,6 +572,7 @@ impl<'a> ExtCtxt<'a> {
         match self.backtrace {
             NO_EXPANSION => self.bug("tried to pop without a push"),
             expn_id => {
+                self.recursion_count -= 1;
                 self.backtrace = self.codemap().with_expn_info(expn_id, |expn_info| {
                     expn_info.map_or(NO_EXPANSION, |ei| ei.call_site.expn_id)
                 });

src/libsyntax/ext/expand.rs

@@ -1069,6 +1069,7 @@ pub struct ExpansionConfig {
     pub crate_name: String,
     pub deriving_hash_type_parameter: bool,
     pub enable_quotes: bool,
+    pub recursion_limit: uint,
 }
 
 impl ExpansionConfig {
@@ -1077,6 +1078,7 @@ impl ExpansionConfig {
             crate_name: crate_name,
             deriving_hash_type_parameter: false,
             enable_quotes: false,
+            recursion_limit: 64,
         }
     }
 }

src/test/compile-fail/infinite-macro-expansion.rs

@@ -0,0 +1,22 @@
+// Copyright 2014 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.
+
+#![feature(macro_rules)]
+
+macro_rules! recursive(
+      () => (
+                recursive!() //~ ERROR Recursion limit reached while expanding the macro `recursive`
+              )
+      )
+
+fn main() {
+    recursive!()
+}
+