Move `CrateConfig` from `Crate` to `ParseSess`.

39 files changed, 130 insertions, 298 deletions

diff --git a/src/libproc_macro/lib.rs b/src/libproc_macro/lib.rs
index 4b9b92fb3bb..1d2c64d6d93 100644
--- a/src/libproc_macro/lib.rs
+++ b/src/libproc_macro/lib.rs
@@ -136,10 +136,8 @@ impl FromStr for TokenStream {
     fn from_str(src: &str) -> Result<TokenStream, LexError> {
         __internal::with_parse_sess(|sess| {
             let src = src.to_string();
-            let cfg = Vec::new();
             let name = "<proc-macro source code>".to_string();
-            let mut parser = parse::new_parser_from_source_str(sess, cfg, name,
-                                                               src);
+            let mut parser = parse::new_parser_from_source_str(sess, name, src);
             let mut ret = TokenStream { inner: Vec::new() };
             loop {
                 match parser.parse_item() {
diff --git a/src/librustc/hir/lowering.rs b/src/librustc/hir/lowering.rs
index 11f635847a0..a489567fbb2 100644
--- a/src/librustc/hir/lowering.rs
+++ b/src/librustc/hir/lowering.rs
@@ -124,7 +124,6 @@ impl<'a> LoweringContext<'a> {
         hir::Crate {
             module: self.lower_mod(&c.module),
             attrs: self.lower_attrs(&c.attrs),
-            config: c.config.clone().into(),
             span: c.span,
             exported_macros: c.exported_macros.iter().map(|m| self.lower_macro_def(m)).collect(),
             items: items,
diff --git a/src/librustc/hir/mod.rs b/src/librustc/hir/mod.rs
index 1ac0a48713a..ed83e228a23 100644
--- a/src/librustc/hir/mod.rs
+++ b/src/librustc/hir/mod.rs
@@ -413,7 +413,6 @@ pub type CrateConfig = HirVec<P<MetaItem>>;
 pub struct Crate {
     pub module: Mod,
     pub attrs: HirVec<Attribute>,
-    pub config: CrateConfig,
     pub span: Span,
     pub exported_macros: HirVec<MacroDef>,
 
diff --git a/src/librustc/session/config.rs b/src/librustc/session/config.rs
index 0ad53529dd1..7b5413984a2 100644
--- a/src/librustc/session/config.rs
+++ b/src/librustc/session/config.rs
@@ -1237,10 +1237,9 @@ pub fn rustc_optgroups() -> Vec<RustcOptGroup> {
 pub fn parse_cfgspecs(cfgspecs: Vec<String> ) -> ast::CrateConfig {
     cfgspecs.into_iter().map(|s| {
         let sess = parse::ParseSess::new();
-        let mut parser = parse::new_parser_from_source_str(&sess,
-                                                           Vec::new(),
-                                                           "cfgspec".to_string(),
-                                                           s.to_string());
+        let mut parser =
+            parse::new_parser_from_source_str(&sess, "cfgspec".to_string(), s.to_string());
+
         let meta_item = panictry!(parser.parse_meta_item());
 
         if !parser.reader.is_eof() {
diff --git a/src/librustc_driver/driver.rs b/src/librustc_driver/driver.rs
index 9b27f7a29e9..a629a2a7fa9 100644
--- a/src/librustc_driver/driver.rs
+++ b/src/librustc_driver/driver.rs
@@ -68,7 +68,6 @@ pub struct Resolutions {
 
 pub fn compile_input(sess: &Session,
                      cstore: &CStore,
-                     cfg: ast::CrateConfig,
                      input: &Input,
                      outdir: &Option<PathBuf>,
                      output: &Option<PathBuf>,
@@ -92,7 +91,7 @@ pub fn compile_input(sess: &Session,
     // large chunks of memory alive and we want to free them as soon as
     // possible to keep the peak memory usage low
     let (outputs, trans) = {
-        let krate = match phase_1_parse_input(sess, cfg, input) {
+        let krate = match phase_1_parse_input(sess, input) {
             Ok(krate) => krate,
             Err(mut parse_error) => {
                 parse_error.emit();
@@ -491,23 +490,17 @@ impl<'a, 'b, 'ast, 'tcx> CompileState<'a, 'b, 'ast, 'tcx> {
     }
 }
 
-pub fn phase_1_parse_input<'a>(sess: &'a Session,
-                               cfg: ast::CrateConfig,
-                               input: &Input)
-                               -> PResult<'a, ast::Crate> {
+pub fn phase_1_parse_input<'a>(sess: &'a Session, input: &Input) -> PResult<'a, ast::Crate> {
     let continue_after_error = sess.opts.debugging_opts.continue_parse_after_error;
     sess.diagnostic().set_continue_after_error(continue_after_error);
 
     let krate = time(sess.time_passes(), "parsing", || {
         match *input {
             Input::File(ref file) => {
-                parse::parse_crate_from_file(file, cfg.clone(), &sess.parse_sess)
+                parse::parse_crate_from_file(file, &sess.parse_sess)
             }
             Input::Str { ref input, ref name } => {
-                parse::parse_crate_from_source_str(name.clone(),
-                                                   input.clone(),
-                                                   cfg.clone(),
-                                                   &sess.parse_sess)
+                parse::parse_crate_from_source_str(name.clone(), input.clone(), &sess.parse_sess)
             }
         }
     })?;
@@ -645,7 +638,7 @@ pub fn phase_2_configure_and_expand<'a, F>(sess: &Session,
     // its contents but the results of name resolution on those contents. Hopefully we'll push
     // this back at some point.
     let _ignore = sess.dep_graph.in_ignore();
-    let mut crate_loader = CrateLoader::new(sess, &cstore, crate_name, krate.config.clone());
+    let mut crate_loader = CrateLoader::new(sess, &cstore, crate_name);
     crate_loader.preprocess(&krate);
     let resolver_arenas = Resolver::arenas();
     let mut resolver =
@@ -686,7 +679,7 @@ pub fn phase_2_configure_and_expand<'a, F>(sess: &Session,
             should_test: sess.opts.test,
             ..syntax::ext::expand::ExpansionConfig::default(crate_name.to_string())
         };
-        let mut ecx = ExtCtxt::new(&sess.parse_sess, krate.config.clone(), cfg, &mut resolver);
+        let mut ecx = ExtCtxt::new(&sess.parse_sess, cfg, &mut resolver);
         let err_count = ecx.parse_sess.span_diagnostic.err_count();
 
         let krate = ecx.monotonic_expander().expand_crate(krate);
diff --git a/src/librustc_driver/lib.rs b/src/librustc_driver/lib.rs
index cb001688da2..f4cae912898 100644
--- a/src/librustc_driver/lib.rs
+++ b/src/librustc_driver/lib.rs
@@ -205,24 +205,20 @@ pub fn run_compiler<'a>(args: &[String],
 
     let loader = file_loader.unwrap_or(box RealFileLoader);
     let codemap = Rc::new(CodeMap::with_file_loader(loader));
-    let sess = session::build_session_with_codemap(sopts,
-                                                   &dep_graph,
-                                                   input_file_path,
-                                                   descriptions,
-                                                   cstore.clone(),
-                                                   codemap,
-                                                   emitter_dest);
+    let mut sess = session::build_session_with_codemap(
+        sopts, &dep_graph, input_file_path, descriptions, cstore.clone(), codemap, emitter_dest,
+    );
     rustc_lint::register_builtins(&mut sess.lint_store.borrow_mut(), Some(&sess));
+
     let mut cfg = config::build_configuration(&sess, cfg);
     target_features::add_configuration(&mut cfg, &sess);
+    sess.parse_sess.config = cfg;
 
-    do_or_return!(callbacks.late_callback(&matches, &sess, &cfg, &input, &odir, &ofile),
-                  Some(sess));
+    do_or_return!(callbacks.late_callback(&matches, &sess, &input, &odir, &ofile), Some(sess));
 
     let plugins = sess.opts.debugging_opts.extra_plugins.clone();
     let control = callbacks.build_controller(&sess, &matches);
-    (driver::compile_input(&sess, &cstore, cfg, &input, &odir, &ofile,
-                           Some(plugins), &control),
+    (driver::compile_input(&sess, &cstore, &input, &odir, &ofile, Some(plugins), &control),
      Some(sess))
 }
 
@@ -310,7 +306,6 @@ pub trait CompilerCalls<'a> {
     fn late_callback(&mut self,
                      _: &getopts::Matches,
                      _: &Session,
-                     _: &ast::CrateConfig,
                      _: &Input,
                      _: &Option<PathBuf>,
                      _: &Option<PathBuf>)
@@ -439,7 +434,7 @@ impl<'a> CompilerCalls<'a> for RustcDefaultCalls {
                 }
                 let dep_graph = DepGraph::new(sopts.build_dep_graph());
                 let cstore = Rc::new(CStore::new(&dep_graph));
-                let sess = build_session(sopts.clone(),
+                let mut sess = build_session(sopts.clone(),
                     &dep_graph,
                     None,
                     descriptions.clone(),
@@ -447,11 +442,10 @@ impl<'a> CompilerCalls<'a> for RustcDefaultCalls {
                 rustc_lint::register_builtins(&mut sess.lint_store.borrow_mut(), Some(&sess));
                 let mut cfg = config::build_configuration(&sess, cfg.clone());
                 target_features::add_configuration(&mut cfg, &sess);
-                let should_stop = RustcDefaultCalls::print_crate_info(&sess,
-                                                                      &cfg,
-                                                                      None,
-                                                                      odir,
-                                                                      ofile);
+                sess.parse_sess.config = cfg;
+                let should_stop =
+                    RustcDefaultCalls::print_crate_info(&sess, None, odir, ofile);
+
                 if should_stop == Compilation::Stop {
                     return None;
                 }
@@ -467,12 +461,11 @@ impl<'a> CompilerCalls<'a> for RustcDefaultCalls {
     fn late_callback(&mut self,
                      matches: &getopts::Matches,
                      sess: &Session,
-                     cfg: &ast::CrateConfig,
                      input: &Input,
                      odir: &Option<PathBuf>,
                      ofile: &Option<PathBuf>)
                      -> Compilation {
-        RustcDefaultCalls::print_crate_info(sess, cfg, Some(input), odir, ofile)
+        RustcDefaultCalls::print_crate_info(sess, Some(input), odir, ofile)
             .and_then(|| RustcDefaultCalls::list_metadata(sess, matches, input))
     }
 
@@ -593,7 +586,6 @@ impl RustcDefaultCalls {
 
 
     fn print_crate_info(sess: &Session,
-                        cfg: &ast::CrateConfig,
                         input: Option<&Input>,
                         odir: &Option<PathBuf>,
                         ofile: &Option<PathBuf>)
@@ -649,8 +641,8 @@ impl RustcDefaultCalls {
                     let allow_unstable_cfg = UnstableFeatures::from_environment()
                         .is_nightly_build();
 
-                    for cfg in cfg {
-                        if !allow_unstable_cfg && GatedCfg::gate(&*cfg).is_some() {
+                    for cfg in &sess.parse_sess.config {
+                        if !allow_unstable_cfg && GatedCfg::gate(cfg).is_some() {
                             continue;
                         }
 
@@ -1036,13 +1028,10 @@ pub fn handle_options(args: &[String]) -> Option<getopts::Matches> {
 fn parse_crate_attrs<'a>(sess: &'a Session, input: &Input) -> PResult<'a, Vec<ast::Attribute>> {
     match *input {
         Input::File(ref ifile) => {
-            parse::parse_crate_attrs_from_file(ifile, Vec::new(), &sess.parse_sess)
+            parse::parse_crate_attrs_from_file(ifile, &sess.parse_sess)
         }
         Input::Str { ref name, ref input } => {
-            parse::parse_crate_attrs_from_source_str(name.clone(),
-                                                     input.clone(),
-                                                     Vec::new(),
-                                                     &sess.parse_sess)
+            parse::parse_crate_attrs_from_source_str(name.clone(), input.clone(), &sess.parse_sess)
         }
     }
 }
diff --git a/src/librustc_driver/test.rs b/src/librustc_driver/test.rs
index c400610a688..50903c89a58 100644
--- a/src/librustc_driver/test.rs
+++ b/src/librustc_driver/test.rs
@@ -106,12 +106,11 @@ fn test_env<F>(source_string: &str,
     let sess = session::build_session_(options, &dep_graph, None, diagnostic_handler,
                                        Rc::new(CodeMap::new()), cstore.clone());
     rustc_lint::register_builtins(&mut sess.lint_store.borrow_mut(), Some(&sess));
-    let krate_config = Vec::new();
     let input = config::Input::Str {
         name: driver::anon_src(),
         input: source_string.to_string(),
     };
-    let krate = driver::phase_1_parse_input(&sess, krate_config, &input).unwrap();
+    let krate = driver::phase_1_parse_input(&sess, &input).unwrap();
     let driver::ExpansionResult { defs, resolutions, mut hir_forest, .. } = {
         driver::phase_2_configure_and_expand(
             &sess, &cstore, krate, None, "test", None, MakeGlobMap::No, |_| Ok(()),
diff --git a/src/librustc_incremental/persist/dirty_clean.rs b/src/librustc_incremental/persist/dirty_clean.rs
index 0418148ffc7..94478f6603a 100644
--- a/src/librustc_incremental/persist/dirty_clean.rs
+++ b/src/librustc_incremental/persist/dirty_clean.rs
@@ -264,7 +264,7 @@ impl<'a, 'tcx, 'm> DirtyCleanMetadataVisitor<'a, 'tcx, 'm> {
 /// flag called `foo`.
 fn check_config(tcx: TyCtxt, attr: &ast::Attribute) -> bool {
     debug!("check_config(attr={:?})", attr);
-    let config = &tcx.map.krate().config;
+    let config = &tcx.sess.parse_sess.config;
     debug!("check_config: config={:?}", config);
     for item in attr.meta_item_list().unwrap_or(&[]) {
         if item.check_name(CFG) {
diff --git a/src/librustc_metadata/creader.rs b/src/librustc_metadata/creader.rs
index d160d29af7d..f4558a2871d 100644
--- a/src/librustc_metadata/creader.rs
+++ b/src/librustc_metadata/creader.rs
@@ -52,7 +52,6 @@ pub struct CrateLoader<'a> {
     next_crate_num: CrateNum,
     foreign_item_map: FnvHashMap<String, Vec<ast::NodeId>>,
     local_crate_name: String,
-    local_crate_config: ast::CrateConfig,
 }
 
 fn dump_crates(cstore: &CStore) {
@@ -144,18 +143,13 @@ enum LoadResult {
 }
 
 impl<'a> CrateLoader<'a> {
-    pub fn new(sess: &'a Session,
-               cstore: &'a CStore,
-               local_crate_name: &str,
-               local_crate_config: ast::CrateConfig)
-               -> Self {
+    pub fn new(sess: &'a Session, cstore: &'a CStore, local_crate_name: &str) -> Self {
         CrateLoader {
             sess: sess,
             cstore: cstore,
             next_crate_num: cstore.next_crate_num(),
             foreign_item_map: FnvHashMap(),
             local_crate_name: local_crate_name.to_owned(),
-            local_crate_config: local_crate_config,
         }
     }
 
@@ -541,7 +535,6 @@ impl<'a> CrateLoader<'a> {
             // NB: Don't use parse::parse_tts_from_source_str because it parses with
             // quote_depth > 0.
             let mut p = parse::new_parser_from_source_str(&self.sess.parse_sess,
-                                                          self.local_crate_config.clone(),
                                                           source_name.clone(),
                                                           def.body);
             let lo = p.span.lo;
diff --git a/src/librustc_plugin/load.rs b/src/librustc_plugin/load.rs
index 669df3ad950..4438241999a 100644
--- a/src/librustc_plugin/load.rs
+++ b/src/librustc_plugin/load.rs
@@ -47,7 +47,7 @@ pub fn load_plugins(sess: &Session,
                     krate: &ast::Crate,
                     crate_name: &str,
                     addl_plugins: Option<Vec<String>>) -> Vec<PluginRegistrar> {
-    let mut loader = PluginLoader::new(sess, cstore, crate_name, krate.config.clone());
+    let mut loader = PluginLoader::new(sess, cstore, crate_name);
 
     // do not report any error now. since crate attributes are
     // not touched by expansion, every use of plugin without
@@ -89,14 +89,10 @@ pub fn load_plugins(sess: &Session,
 }
 
 impl<'a> PluginLoader<'a> {
-    fn new(sess: &'a Session,
-           cstore: &'a CStore,
-           crate_name: &str,
-           crate_config: ast::CrateConfig)
-            -> PluginLoader<'a> {
+    fn new(sess: &'a Session, cstore: &'a CStore, crate_name: &str) -> Self {
         PluginLoader {
             sess: sess,
-            reader: CrateLoader::new(sess, cstore, crate_name, crate_config),
+            reader: CrateLoader::new(sess, cstore, crate_name),
             plugins: vec![],
         }
     }
diff --git a/src/librustc_trans/assert_module_sources.rs b/src/librustc_trans/assert_module_sources.rs
index 7fe6d2bbfe2..264ed4cd12f 100644
--- a/src/librustc_trans/assert_module_sources.rs
+++ b/src/librustc_trans/assert_module_sources.rs
@@ -134,7 +134,7 @@ impl<'a, 'tcx> AssertModuleSource<'a, 'tcx> {
     /// Scan for a `cfg="foo"` attribute and check whether we have a
     /// cfg flag called `foo`.
     fn check_config(&self, attr: &ast::Attribute) -> bool {
-        let config = &self.tcx.map.krate().config;
+        let config = &self.tcx.sess.parse_sess.config;
         let value = self.field(attr, CFG);
         debug!("check_config(config={:?}, value={:?})", config, value);
         if config.iter().any(|c| c.check_name(&value[..])) {
diff --git a/src/librustdoc/core.rs b/src/librustdoc/core.rs
index 208819a4a0b..d18e4c8d29c 100644
--- a/src/librustdoc/core.rs
+++ b/src/librustdoc/core.rs
@@ -163,14 +163,16 @@ pub fn run_core(search_paths: SearchPaths,
     let dep_graph = DepGraph::new(false);
     let _ignore = dep_graph.in_ignore();
     let cstore = Rc::new(CStore::new(&dep_graph));
-    let sess = session::build_session_(sessopts, &dep_graph, cpath, diagnostic_handler,
-                                       codemap, cstore.clone());
+    let mut sess = session::build_session_(
+        sessopts, &dep_graph, cpath, diagnostic_handler, codemap, cstore.clone()
+    );
     rustc_lint::register_builtins(&mut sess.lint_store.borrow_mut(), Some(&sess));
 
     let mut cfg = config::build_configuration(&sess, config::parse_cfgspecs(cfgs));
     target_features::add_configuration(&mut cfg, &sess);
+    sess.parse_sess.config = cfg;
 
-    let krate = panictry!(driver::phase_1_parse_input(&sess, cfg, &input));
+    let krate = panictry!(driver::phase_1_parse_input(&sess, &input));
 
     let name = link::find_crate_name(Some(&sess), &krate.attrs, &input);
 
diff --git a/src/librustdoc/test.rs b/src/librustdoc/test.rs
index d1d2b14806f..45c3d413500 100644
--- a/src/librustdoc/test.rs
+++ b/src/librustdoc/test.rs
@@ -73,24 +73,20 @@ pub fn run(input: &str,
     };
 
     let codemap = Rc::new(CodeMap::new());
-    let diagnostic_handler = errors::Handler::with_tty_emitter(ColorConfig::Auto,
-                                                               true,
-                                                               false,
-                                                               Some(codemap.clone()));
+    let handler =
+        errors::Handler::with_tty_emitter(ColorConfig::Auto, true, false, Some(codemap.clone()));
 
     let dep_graph = DepGraph::new(false);
     let _ignore = dep_graph.in_ignore();
     let cstore = Rc::new(CStore::new(&dep_graph));
-    let sess = session::build_session_(sessopts,
-                                       &dep_graph,
-                                       Some(input_path.clone()),
-                                       diagnostic_handler,
-                                       codemap,
-                                       cstore.clone());
+    let mut sess = session::build_session_(
+        sessopts, &dep_graph, Some(input_path.clone()), handler, codemap, cstore.clone(),
+    );
     rustc_lint::register_builtins(&mut sess.lint_store.borrow_mut(), Some(&sess));
+    sess.parse_sess.config =
+        config::build_configuration(&sess, config::parse_cfgspecs(cfgs.clone()));
 
-    let cfg = config::build_configuration(&sess, config::parse_cfgspecs(cfgs.clone()));
-    let krate = panictry!(driver::phase_1_parse_input(&sess, cfg, &input));
+    let krate = panictry!(driver::phase_1_parse_input(&sess, &input));
     let driver::ExpansionResult { defs, mut hir_forest, .. } = {
         phase_2_configure_and_expand(
             &sess, &cstore, krate, None, "rustdoc-test", None, MakeGlobMap::No, |_| Ok(())
@@ -236,18 +232,16 @@ fn runtest(test: &str, cratename: &str, cfgs: Vec<String>, libs: SearchPaths,
 
     let dep_graph = DepGraph::new(false);
     let cstore = Rc::new(CStore::new(&dep_graph));
-    let sess = session::build_session_(sessopts,
-                                       &dep_graph,
-                                       None,
-                                       diagnostic_handler,
-                                       codemap,
-                                       cstore.clone());
+    let mut sess = session::build_session_(
+        sessopts, &dep_graph, None, diagnostic_handler, codemap, cstore.clone(),
+    );
     rustc_lint::register_builtins(&mut sess.lint_store.borrow_mut(), Some(&sess));
 
     let outdir = Mutex::new(TempDir::new("rustdoctest").ok().expect("rustdoc needs a tempdir"));
     let libdir = sess.target_filesearch(PathKind::All).get_lib_path();
     let mut control = driver::CompileController::basic();
-    let cfg = config::build_configuration(&sess, config::parse_cfgspecs(cfgs.clone()));
+    sess.parse_sess.config =
+        config::build_configuration(&sess, config::parse_cfgspecs(cfgs.clone()));
     let out = Some(outdir.lock().unwrap().path().to_path_buf());
 
     if no_run {
@@ -255,9 +249,7 @@ fn runtest(test: &str, cratename: &str, cfgs: Vec<String>, libs: SearchPaths,
     }
 
     let res = panic::catch_unwind(AssertUnwindSafe(|| {
-        driver::compile_input(&sess, &cstore, cfg.clone(),
-                              &input, &out,
-                              &None, None, &control)
+        driver::compile_input(&sess, &cstore, &input, &out, &None, None, &control)
     }));
 
     match res {
diff --git a/src/libsyntax/ast.rs b/src/libsyntax/ast.rs
index 37e306de325..8864694c932 100644
--- a/src/libsyntax/ast.rs
+++ b/src/libsyntax/ast.rs
@@ -477,7 +477,6 @@ pub type CrateConfig = Vec<P<MetaItem>>;
 pub struct Crate {
     pub module: Mod,
     pub attrs: Vec<Attribute>,
-    pub config: CrateConfig,
     pub span: Span,
     pub exported_macros: Vec<MacroDef>,
 }
diff --git a/src/libsyntax/attr.rs b/src/libsyntax/attr.rs
index dc02c26039c..0335f210347 100644
--- a/src/libsyntax/attr.rs
+++ b/src/libsyntax/attr.rs
@@ -501,10 +501,7 @@ pub fn requests_inline(attrs: &[Attribute]) -> bool {
 }
 
 /// Tests if a cfg-pattern matches the cfg set
-pub fn cfg_matches(cfgs: &[P<MetaItem>], cfg: &ast::MetaItem,
-                   sess: &ParseSess,
-                   features: Option<&Features>)
-                   -> bool {
+pub fn cfg_matches(cfg: &ast::MetaItem, sess: &ParseSess, features: Option<&Features>) -> bool {
     match cfg.node {
         ast::MetaItemKind::List(ref pred, ref mis) => {
             for mi in mis.iter() {
@@ -518,10 +515,10 @@ pub fn cfg_matches(cfgs: &[P<MetaItem>], cfg: &ast::MetaItem,
             // that they won't fail with the loop above.
             match &pred[..] {
                 "any" => mis.iter().any(|mi| {
-                    cfg_matches(cfgs, mi.meta_item().unwrap(), sess, features)
+                    cfg_matches(mi.meta_item().unwrap(), sess, features)
                 }),
                 "all" => mis.iter().all(|mi| {
-                    cfg_matches(cfgs, mi.meta_item().unwrap(), sess, features)
+                    cfg_matches(mi.meta_item().unwrap(), sess, features)
                 }),
                 "not" => {
                     if mis.len() != 1 {
@@ -529,7 +526,7 @@ pub fn cfg_matches(cfgs: &[P<MetaItem>], cfg: &ast::MetaItem,
                         return false;
                     }
 
-                    !cfg_matches(cfgs, mis[0].meta_item().unwrap(), sess, features)
+                    !cfg_matches(mis[0].meta_item().unwrap(), sess, features)
                 },
                 p => {
                     span_err!(sess.span_diagnostic, cfg.span, E0537, "invalid predicate `{}`", p);
@@ -541,7 +538,7 @@ pub fn cfg_matches(cfgs: &[P<MetaItem>], cfg: &ast::MetaItem,
             if let (Some(feats), Some(gated_cfg)) = (features, GatedCfg::gate(cfg)) {
                 gated_cfg.check_and_emit(sess, feats);
             }
-            contains(cfgs, cfg)
+            contains(&sess.config, cfg)
         }
     }
 }
diff --git a/src/libsyntax/config.rs b/src/libsyntax/config.rs
index 01f81e5e2de..946257a16d5 100644
--- a/src/libsyntax/config.rs
+++ b/src/libsyntax/config.rs
@@ -20,7 +20,6 @@ use util::small_vector::SmallVector;
 
 /// A folder that strips out items that do not belong in the current configuration.
 pub struct StripUnconfigured<'a> {
-    pub config: &'a ast::CrateConfig,
     pub should_test: bool,
     pub sess: &'a ParseSess,
     pub features: Option<&'a Features>,
@@ -32,7 +31,6 @@ pub fn features(mut krate: ast::Crate, sess: &ParseSess, should_test: bool)
     let features;
     {
         let mut strip_unconfigured = StripUnconfigured {
-            config: &krate.config.clone(),
             should_test: should_test,
             sess: sess,
             features: None,
@@ -107,7 +105,7 @@ impl<'a> StripUnconfigured<'a> {
         use attr::cfg_matches;
         match (cfg.meta_item(), mi.meta_item()) {
             (Some(cfg), Some(mi)) =>
-                if cfg_matches(self.config, &cfg, self.sess, self.features) {
+                if cfg_matches(&cfg, self.sess, self.features) {
                     self.process_cfg_attr(respan(mi.span, ast::Attribute_ {
                         id: attr::mk_attr_id(),
                         style: attr.node.style,
@@ -148,7 +146,7 @@ impl<'a> StripUnconfigured<'a> {
                 return true;
             }
 
-            attr::cfg_matches(self.config, mis[0].meta_item().unwrap(), self.sess, self.features)
+            attr::cfg_matches(mis[0].meta_item().unwrap(), self.sess, self.features)
         })
     }
 
diff --git a/src/libsyntax/ext/base.rs b/src/libsyntax/ext/base.rs
index c404c6d1162..cc097ab0efa 100644
--- a/src/libsyntax/ext/base.rs
+++ b/src/libsyntax/ext/base.rs
@@ -574,7 +574,6 @@ pub struct ExpansionData {
 /// -> expn_info of their expansion context stored into their span.
 pub struct ExtCtxt<'a> {
     pub parse_sess: &'a parse::ParseSess,
-    pub cfg: ast::CrateConfig,
     pub ecfg: expand::ExpansionConfig<'a>,
     pub crate_root: Option<&'static str>,
     pub resolver: &'a mut Resolver,
@@ -583,13 +582,12 @@ pub struct ExtCtxt<'a> {
 }
 
 impl<'a> ExtCtxt<'a> {
-    pub fn new(parse_sess: &'a parse::ParseSess, cfg: ast::CrateConfig,
+    pub fn new(parse_sess: &'a parse::ParseSess,
                ecfg: expand::ExpansionConfig<'a>,
                resolver: &'a mut Resolver)
                -> ExtCtxt<'a> {
         ExtCtxt {
             parse_sess: parse_sess,
-            cfg: cfg,
             ecfg: ecfg,
             crate_root: None,
             resolver: resolver,
@@ -617,11 +615,11 @@ impl<'a> ExtCtxt<'a> {
 
     pub fn new_parser_from_tts(&self, tts: &[tokenstream::TokenTree])
         -> parser::Parser<'a> {
-        parse::tts_to_parser(self.parse_sess, tts.to_vec(), self.cfg().clone())
+        parse::tts_to_parser(self.parse_sess, tts.to_vec())
     }
     pub fn codemap(&self) -> &'a CodeMap { self.parse_sess.codemap() }
     pub fn parse_sess(&self) -> &'a parse::ParseSess { self.parse_sess }
-    pub fn cfg(&self) -> &ast::CrateConfig { &self.cfg }
+    pub fn cfg(&self) -> &ast::CrateConfig { &self.parse_sess.config }
     pub fn call_site(&self) -> Span {
         self.codemap().with_expn_info(self.backtrace(), |ei| match ei {
             Some(expn_info) => expn_info.call_site,
diff --git a/src/libsyntax/ext/expand.rs b/src/libsyntax/ext/expand.rs
index e84a9208029..e3b23e239f9 100644
--- a/src/libsyntax/ext/expand.rs
+++ b/src/libsyntax/ext/expand.rs
@@ -293,11 +293,9 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
     }
 
     fn collect_invocations(&mut self, expansion: Expansion) -> (Expansion, Vec<Invocation>) {
-        let crate_config = mem::replace(&mut self.cx.cfg, Vec::new());
         let result = {
             let mut collector = InvocationCollector {
                 cfg: StripUnconfigured {
-                    config: &crate_config,
                     should_test: self.cx.ecfg.should_test,
                     sess: self.cx.parse_sess,
                     features: self.cx.ecfg.features,
@@ -308,7 +306,6 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
             };
             (expansion.fold_with(&mut collector), collector.invocations)
         };
-        self.cx.cfg = crate_config;
 
         if self.monotonic {
             let err_count = self.cx.parse_sess.span_diagnostic.err_count();
@@ -646,7 +643,7 @@ fn string_to_tts(text: String, parse_sess: &ParseSess) -> Vec<TokenTree> {
                             .new_filemap(String::from("<macro expansion>"), None, text);
 
     let lexer = lexer::StringReader::new(&parse_sess.span_diagnostic, filemap);
-    let mut parser = Parser::new(parse_sess, Vec::new(), Box::new(lexer));
+    let mut parser = Parser::new(parse_sess, Box::new(lexer));
     panictry!(parser.parse_all_token_trees())
 }
 
diff --git a/src/libsyntax/ext/quote.rs b/src/libsyntax/ext/quote.rs
index 7f002d28166..f3497c130bf 100644
--- a/src/libsyntax/ext/quote.rs
+++ b/src/libsyntax/ext/quote.rs
@@ -331,7 +331,6 @@ pub mod rt {
             panictry!(parse::parse_item_from_source_str(
                 "<quote expansion>".to_string(),
                 s,
-                self.cfg().clone(),
                 self.parse_sess())).expect("parse error")
         }
 
@@ -339,7 +338,6 @@ pub mod rt {
             panictry!(parse::parse_stmt_from_source_str(
                 "<quote expansion>".to_string(),
                 s,
-                self.cfg().clone(),
                 self.parse_sess())).expect("parse error")
         }
 
@@ -347,7 +345,6 @@ pub mod rt {
             panictry!(parse::parse_expr_from_source_str(
                 "<quote expansion>".to_string(),
                 s,
-                self.cfg().clone(),
                 self.parse_sess()))
         }
 
@@ -355,7 +352,6 @@ pub mod rt {
             panictry!(parse::parse_tts_from_source_str(
                 "<quote expansion>".to_string(),
                 s,
-                self.cfg().clone(),
                 self.parse_sess()))
         }
     }
@@ -920,14 +916,6 @@ fn expand_parse_call(cx: &ExtCtxt,
                      tts: &[TokenTree]) -> P<ast::Expr> {
     let (cx_expr, tts_expr) = expand_tts(cx, sp, tts);
 
-    let cfg_call = || cx.expr_method_call(
-        sp, cx.expr_ident(sp, id_ext("ext_cx")),
-        id_ext("cfg"), Vec::new());
-
-    let cfg_clone_call = || cx.expr_method_call(
-        sp, cfg_call(),
-        id_ext("clone"), Vec::new());
-
     let parse_sess_call = || cx.expr_method_call(
         sp, cx.expr_ident(sp, id_ext("ext_cx")),
         id_ext("parse_sess"), Vec::new());
@@ -935,7 +923,7 @@ fn expand_parse_call(cx: &ExtCtxt,
     let new_parser_call =
         cx.expr_call(sp,
                      cx.expr_ident(sp, id_ext("new_parser_from_tts")),
-                     vec!(parse_sess_call(), cfg_clone_call(), tts_expr));
+                     vec!(parse_sess_call(), tts_expr));
 
     let path = vec![id_ext("syntax"), id_ext("ext"), id_ext("quote"), id_ext(parse_method)];
     let mut args = vec![cx.expr_mut_addr_of(sp, new_parser_call)];
diff --git a/src/libsyntax/ext/source_util.rs b/src/libsyntax/ext/source_util.rs
index 30dc1823b37..ec48cae3f76 100644
--- a/src/libsyntax/ext/source_util.rs
+++ b/src/libsyntax/ext/source_util.rs
@@ -92,15 +92,8 @@ pub fn expand_include<'cx>(cx: &'cx mut ExtCtxt, sp: Span, tts: &[tokenstream::T
         None => return DummyResult::expr(sp),
     };
     // The file will be added to the code map by the parser
-    let p =
-        parse::new_sub_parser_from_file(cx.parse_sess(),
-                                        cx.cfg().clone(),
-                                        &res_rel_file(cx,
-                                                      sp,
-                                                      Path::new(&file)),
-                                        true,
-                                        None,
-                                        sp);
+    let path = res_rel_file(cx, sp, Path::new(&file));
+    let p = parse::new_sub_parser_from_file(cx.parse_sess(), &path, true, None, sp);
 
     struct ExpandResult<'a> {
         p: parse::parser::Parser<'a>,
diff --git a/src/libsyntax/ext/tt/macro_parser.rs b/src/libsyntax/ext/tt/macro_parser.rs
index 91675065eb8..7e3fe328569 100644
--- a/src/libsyntax/ext/tt/macro_parser.rs
+++ b/src/libsyntax/ext/tt/macro_parser.rs
@@ -78,7 +78,6 @@ pub use self::NamedMatch::*;
 pub use self::ParseResult::*;
 use self::TokenTreeOrTokenTreeVec::*;
 
-use ast;
 use ast::Ident;
 use syntax_pos::{self, BytePos, mk_sp, Span};
 use codemap::Spanned;
@@ -280,11 +279,7 @@ pub fn token_name_eq(t1 : &Token, t2 : &Token) -> bool {
     }
 }
 
-pub fn parse(sess: &ParseSess,
-             cfg: &ast::CrateConfig,
-             mut rdr: TtReader,
-             ms: &[TokenTree])
-             -> NamedParseResult {
+pub fn parse(sess: &ParseSess, mut rdr: TtReader, ms: &[TokenTree]) -> NamedParseResult {
     let mut cur_eis = SmallVector::one(initial_matcher_pos(ms.to_owned(),
                                                            None,
                                                            rdr.peek().sp.lo));
@@ -482,7 +477,7 @@ pub fn parse(sess: &ParseSess,
                 rdr.next_token();
             } else /* bb_eis.len() == 1 */ {
                 rdr.next_tok = {
-                    let mut rust_parser = Parser::new(sess, cfg.clone(), Box::new(&mut rdr));
+                    let mut rust_parser = Parser::new(sess, Box::new(&mut rdr));
                     let mut ei = bb_eis.pop().unwrap();
                     if let TokenTree::Token(span, MatchNt(_, ident)) = ei.top_elts.get_tt(ei.idx) {
                         let match_cur = ei.match_cur;
diff --git a/src/libsyntax/ext/tt/macro_rules.rs b/src/libsyntax/ext/tt/macro_rules.rs
index ceca698f479..431e757368c 100644
--- a/src/libsyntax/ext/tt/macro_rules.rs
+++ b/src/libsyntax/ext/tt/macro_rules.rs
@@ -115,7 +115,7 @@ fn generic_extension<'cx>(cx: &'cx ExtCtxt,
                 // rhs has holes ( `$id` and `$(...)` that need filled)
                 let trncbr =
                     new_tt_reader(&cx.parse_sess.span_diagnostic, Some(named_matches), rhs);
-                let mut p = Parser::new(cx.parse_sess(), cx.cfg().clone(), Box::new(trncbr));
+                let mut p = Parser::new(cx.parse_sess(), Box::new(trncbr));
                 p.directory = cx.current_expansion.module.directory.clone();
                 p.restrictions = match cx.current_expansion.no_noninline_mod {
                     true => Restrictions::NO_NONINLINE_MOD,
@@ -220,7 +220,7 @@ pub fn compile(sess: &ParseSess, def: &ast::MacroDef) -> SyntaxExtension {
     // Parse the macro_rules! invocation (`none` is for no interpolations):
     let arg_reader = new_tt_reader(&sess.span_diagnostic, None, def.body.clone());
 
-    let argument_map = match parse(sess, &Vec::new(), arg_reader, &argument_gram) {
+    let argument_map = match parse(sess, arg_reader, &argument_gram) {
         Success(m) => m,
         Failure(sp, tok) => {
             let s = parse_failure_msg(tok);
diff --git a/src/libsyntax/fold.rs b/src/libsyntax/fold.rs
index 16916ddd5d6..4bf6e55d674 100644
--- a/src/libsyntax/fold.rs
+++ b/src/libsyntax/fold.rs
@@ -972,10 +972,8 @@ pub fn noop_fold_mod<T: Folder>(Mod {inner, items}: Mod, folder: &mut T) -> Mod
     }
 }
 
-pub fn noop_fold_crate<T: Folder>(Crate {module, attrs, config, mut exported_macros, span}: Crate,
+pub fn noop_fold_crate<T: Folder>(Crate {module, attrs, mut exported_macros, span}: Crate,
                                   folder: &mut T) -> Crate {
-    let config = folder.fold_meta_items(config);
-
     let mut items = folder.fold_item(P(ast::Item {
         ident: keywords::Invalid.ident(),
         attrs: attrs,
@@ -1009,7 +1007,6 @@ pub fn noop_fold_crate<T: Folder>(Crate {module, attrs, config, mut exported_mac
     Crate {
         module: module,
         attrs: attrs,
-        config: config,
         exported_macros: exported_macros,
         span: span,
     }
diff --git a/src/libsyntax/parse/mod.rs b/src/libsyntax/parse/mod.rs
index 1a84a750463..7b67c23e102 100644
--- a/src/libsyntax/parse/mod.rs
+++ b/src/libsyntax/parse/mod.rs
@@ -10,7 +10,7 @@
 
 //! The main parser interface
 
-use ast;
+use ast::{self, CrateConfig};
 use codemap::CodeMap;
 use syntax_pos::{self, Span, FileMap};
 use errors::{Handler, ColorConfig, DiagnosticBuilder};
@@ -44,13 +44,14 @@ pub mod obsolete;
 pub struct ParseSess {
     pub span_diagnostic: Handler, // better be the same as the one in the reader!
     pub unstable_features: UnstableFeatures,
+    pub config: CrateConfig,
     /// Used to determine and report recursive mod inclusions
     included_mod_stack: RefCell<Vec<PathBuf>>,
     code_map: Rc<CodeMap>,
 }
 
 impl ParseSess {
-    pub fn new() -> ParseSess {
+    pub fn new() -> Self {
         let cm = Rc::new(CodeMap::new());
         let handler = Handler::with_tty_emitter(ColorConfig::Auto,
                                                 true,
@@ -63,6 +64,7 @@ impl ParseSess {
         ParseSess {
             span_diagnostic: handler,
             unstable_features: UnstableFeatures::from_environment(),
+            config: Vec::new(),
             included_mod_stack: RefCell::new(vec![]),
             code_map: code_map
         }
@@ -78,146 +80,90 @@ impl ParseSess {
 // uses a HOF to parse anything, and <source> includes file and
 // source_str.
 
-pub fn parse_crate_from_file<'a>(input: &Path,
-                                 cfg: ast::CrateConfig,
-                                 sess: &'a ParseSess)
-                                 -> PResult<'a, ast::Crate> {
-    let mut parser = new_parser_from_file(sess, cfg, input);
+pub fn parse_crate_from_file<'a>(input: &Path, sess: &'a ParseSess) -> PResult<'a, ast::Crate> {
+    let mut parser = new_parser_from_file(sess, input);
     parser.parse_crate_mod()
 }
 
-pub fn parse_crate_attrs_from_file<'a>(input: &Path,
-                                       cfg: ast::CrateConfig,
-                                       sess: &'a ParseSess)
+pub fn parse_crate_attrs_from_file<'a>(input: &Path, sess: &'a ParseSess)
                                        -> PResult<'a, Vec<ast::Attribute>> {
-    let mut parser = new_parser_from_file(sess, cfg, input);
+    let mut parser = new_parser_from_file(sess, input);
     parser.parse_inner_attributes()
 }
 
-pub fn parse_crate_from_source_str<'a>(name: String,
-                                       source: String,
-                                       cfg: ast::CrateConfig,
-                                       sess: &'a ParseSess)
+pub fn parse_crate_from_source_str<'a>(name: String, source: String, sess: &'a ParseSess)
                                        -> PResult<'a, ast::Crate> {
-    let mut p = new_parser_from_source_str(sess,
-                                           cfg,
-                                           name,
-                                           source);
-    p.parse_crate_mod()
+    new_parser_from_source_str(sess, name, source).parse_crate_mod()
 }
 
-pub fn parse_crate_attrs_from_source_str<'a>(name: String,
-                                             source: String,
-                                             cfg: ast::CrateConfig,
-                                             sess: &'a ParseSess)
+pub fn parse_crate_attrs_from_source_str<'a>(name: String, source: String, sess: &'a ParseSess)
                                              -> PResult<'a, Vec<ast::Attribute>> {
-    let mut p = new_parser_from_source_str(sess,
-                                           cfg,
-                                           name,
-                                           source);
-    p.parse_inner_attributes()
+    new_parser_from_source_str(sess, name, source).parse_inner_attributes()
 }
 
-pub fn parse_expr_from_source_str<'a>(name: String,
-                                      source: String,
-                                      cfg: ast::CrateConfig,
-                                      sess: &'a ParseSess)
+pub fn parse_expr_from_source_str<'a>(name: String, source: String, sess: &'a ParseSess)
                                       -> PResult<'a, P<ast::Expr>> {
-    let mut p = new_parser_from_source_str(sess, cfg, name, source);
-    p.parse_expr()
+    new_parser_from_source_str(sess, name, source).parse_expr()
 }
 
 /// Parses an item.
 ///
 /// Returns `Ok(Some(item))` when successful, `Ok(None)` when no item was found, and`Err`
 /// when a syntax error occurred.
-pub fn parse_item_from_source_str<'a>(name: String,
-                                      source: String,
-                                      cfg: ast::CrateConfig,
-                                      sess: &'a ParseSess)
+pub fn parse_item_from_source_str<'a>(name: String, source: String, sess: &'a ParseSess)
                                       -> PResult<'a, Option<P<ast::Item>>> {
-    let mut p = new_parser_from_source_str(sess, cfg, name, source);
-    p.parse_item()
+    new_parser_from_source_str(sess, name, source).parse_item()
 }
 
-pub fn parse_meta_from_source_str<'a>(name: String,
-                                      source: String,
-                                      cfg: ast::CrateConfig,
-                                      sess: &'a ParseSess)
+pub fn parse_meta_from_source_str<'a>(name: String, source: String, sess: &'a ParseSess)
                                       -> PResult<'a, P<ast::MetaItem>> {
-    let mut p = new_parser_from_source_str(sess, cfg, name, source);
-    p.parse_meta_item()
+    new_parser_from_source_str(sess, name, source).parse_meta_item()
 }
 
-pub fn parse_stmt_from_source_str<'a>(name: String,
-                                      source: String,
-                                      cfg: ast::CrateConfig,
-                                      sess: &'a ParseSess)
+pub fn parse_stmt_from_source_str<'a>(name: String, source: String, sess: &'a ParseSess)
                                       -> PResult<'a, Option<ast::Stmt>> {
-    let mut p = new_parser_from_source_str(
-        sess,
-        cfg,
-        name,
-        source
-    );
-    p.parse_stmt()
+    new_parser_from_source_str(sess, name, source).parse_stmt()
 }
 
 // Warning: This parses with quote_depth > 0, which is not the default.
-pub fn parse_tts_from_source_str<'a>(name: String,
-                                     source: String,
-                                     cfg: ast::CrateConfig,
-                                     sess: &'a ParseSess)
+pub fn parse_tts_from_source_str<'a>(name: String, source: String, sess: &'a ParseSess)
                                      -> PResult<'a, Vec<tokenstream::TokenTree>> {
-    let mut p = new_parser_from_source_str(
-        sess,
-        cfg,
-        name,
-        source
-    );
+    let mut p = new_parser_from_source_str(sess, name, source);
     p.quote_depth += 1;
     // right now this is re-creating the token trees from ... token trees.
     p.parse_all_token_trees()
 }
 
 // Create a new parser from a source string
-pub fn new_parser_from_source_str<'a>(sess: &'a ParseSess,
-                                      cfg: ast::CrateConfig,
-                                      name: String,
-                                      source: String)
+pub fn new_parser_from_source_str<'a>(sess: &'a ParseSess, name: String, source: String)
                                       -> Parser<'a> {
-    filemap_to_parser(sess, sess.codemap().new_filemap(name, None, source), cfg)
+    filemap_to_parser(sess, sess.codemap().new_filemap(name, None, source))
 }
 
 /// Create a new parser, handling errors as appropriate
 /// if the file doesn't exist
-pub fn new_parser_from_file<'a>(sess: &'a ParseSess,
-                                cfg: ast::CrateConfig,
-                                path: &Path) -> Parser<'a> {
-    filemap_to_parser(sess, file_to_filemap(sess, path, None), cfg)
+pub fn new_parser_from_file<'a>(sess: &'a ParseSess, path: &Path) -> Parser<'a> {
+    filemap_to_parser(sess, file_to_filemap(sess, path, None))
 }
 
 /// Given a session, a crate config, a path, and a span, add
 /// the file at the given path to the codemap, and return a parser.
 /// On an error, use the given span as the source of the problem.
 pub fn new_sub_parser_from_file<'a>(sess: &'a ParseSess,
-                                    cfg: ast::CrateConfig,
                                     path: &Path,
                                     owns_directory: bool,
                                     module_name: Option<String>,
                                     sp: Span) -> Parser<'a> {
-    let mut p = filemap_to_parser(sess, file_to_filemap(sess, path, Some(sp)), cfg);
+    let mut p = filemap_to_parser(sess, file_to_filemap(sess, path, Some(sp)));
     p.owns_directory = owns_directory;
     p.root_module_name = module_name;
     p
 }
 
 /// Given a filemap and config, return a parser
-pub fn filemap_to_parser<'a>(sess: &'a ParseSess,
-                             filemap: Rc<FileMap>,
-                             cfg: ast::CrateConfig) -> Parser<'a> {
+pub fn filemap_to_parser<'a>(sess: &'a ParseSess, filemap: Rc<FileMap>, ) -> Parser<'a> {
     let end_pos = filemap.end_pos;
-    let mut parser = tts_to_parser(sess, filemap_to_tts(sess, filemap), cfg);
+    let mut parser = tts_to_parser(sess, filemap_to_tts(sess, filemap));
 
     if parser.token == token::Eof && parser.span == syntax_pos::DUMMY_SP {
         parser.span = syntax_pos::mk_sp(end_pos, end_pos);
@@ -228,18 +174,13 @@ pub fn filemap_to_parser<'a>(sess: &'a ParseSess,
 
 // must preserve old name for now, because quote! from the *existing*
 // compiler expands into it
-pub fn new_parser_from_tts<'a>(sess: &'a ParseSess,
-                               cfg: ast::CrateConfig,
-                               tts: Vec<tokenstream::TokenTree>)
+pub fn new_parser_from_tts<'a>(sess: &'a ParseSess, tts: Vec<tokenstream::TokenTree>)
                                -> Parser<'a> {
-    tts_to_parser(sess, tts, cfg)
+    tts_to_parser(sess, tts)
 }
 
-pub fn new_parser_from_ts<'a>(sess: &'a ParseSess,
-                              cfg: ast::CrateConfig,
-                              ts: tokenstream::TokenStream)
-                              -> Parser<'a> {
-    tts_to_parser(sess, ts.to_tts(), cfg)
+pub fn new_parser_from_ts<'a>(sess: &'a ParseSess, ts: tokenstream::TokenStream) -> Parser<'a> {
+    tts_to_parser(sess, ts.to_tts())
 }
 
 
@@ -266,18 +207,15 @@ pub fn filemap_to_tts(sess: &ParseSess, filemap: Rc<FileMap>)
     -> Vec<tokenstream::TokenTree> {
     // it appears to me that the cfg doesn't matter here... indeed,
     // parsing tt's probably shouldn't require a parser at all.
-    let cfg = Vec::new();
     let srdr = lexer::StringReader::new(&sess.span_diagnostic, filemap);
-    let mut p1 = Parser::new(sess, cfg, Box::new(srdr));
+    let mut p1 = Parser::new(sess, Box::new(srdr));
     panictry!(p1.parse_all_token_trees())
 }
 
-/// Given tts and cfg, produce a parser
-pub fn tts_to_parser<'a>(sess: &'a ParseSess,
-                         tts: Vec<tokenstream::TokenTree>,
-                         cfg: ast::CrateConfig) -> Parser<'a> {
+/// Given tts and the ParseSess, produce a parser
+pub fn tts_to_parser<'a>(sess: &'a ParseSess, tts: Vec<tokenstream::TokenTree>) -> Parser<'a> {
     let trdr = lexer::new_tt_reader(&sess.span_diagnostic, None, tts);
-    let mut p = Parser::new(sess, cfg, Box::new(trdr));
+    let mut p = Parser::new(sess, Box::new(trdr));
     p.check_unknown_macro_variable();
     p
 }
@@ -1057,13 +995,13 @@ mod tests {
 
         let name = "<source>".to_string();
         let source = "/// doc comment\r\nfn foo() {}".to_string();
-        let item = parse_item_from_source_str(name.clone(), source, Vec::new(), &sess)
+        let item = parse_item_from_source_str(name.clone(), source, &sess)
             .unwrap().unwrap();
         let doc = first_attr_value_str_by_name(&item.attrs, "doc").unwrap();
         assert_eq!(&doc[..], "/// doc comment");
 
         let source = "/// doc comment\r\n/// line 2\r\nfn foo() {}".to_string();
-        let item = parse_item_from_source_str(name.clone(), source, Vec::new(), &sess)
+        let item = parse_item_from_source_str(name.clone(), source, &sess)
             .unwrap().unwrap();
         let docs = item.attrs.iter().filter(|a| &*a.name() == "doc")
                     .map(|a| a.value_str().unwrap().to_string()).collect::<Vec<_>>();
@@ -1071,7 +1009,7 @@ mod tests {
         assert_eq!(&docs[..], b);
 
         let source = "/** doc comment\r\n *  with CRLF */\r\nfn foo() {}".to_string();
-        let item = parse_item_from_source_str(name, source, Vec::new(), &sess).unwrap().unwrap();
+        let item = parse_item_from_source_str(name, source, &sess).unwrap().unwrap();
         let doc = first_attr_value_str_by_name(&item.attrs, "doc").unwrap();
         assert_eq!(&doc[..], "/** doc comment\n *  with CRLF */");
     }
@@ -1080,7 +1018,7 @@ mod tests {
     fn ttdelim_span() {
         let sess = ParseSess::new();
         let expr = parse::parse_expr_from_source_str("foo".to_string(),
-            "foo!( fn main() { body } )".to_string(), vec![], &sess).unwrap();
+            "foo!( fn main() { body } )".to_string(), &sess).unwrap();
 
         let tts = match expr.node {
             ast::ExprKind::Mac(ref mac) => mac.node.tts.clone(),
diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs
index d52d73d70d3..a75937759a2 100644
--- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -15,7 +15,7 @@ use ast::Unsafety;
 use ast::{Mod, Arg, Arm, Attribute, BindingMode, TraitItemKind};
 use ast::Block;
 use ast::{BlockCheckMode, CaptureBy};
-use ast::{Constness, Crate, CrateConfig};
+use ast::{Constness, Crate};
 use ast::Defaultness;
 use ast::EnumDef;
 use ast::{Expr, ExprKind, RangeLimits};
@@ -271,7 +271,6 @@ pub struct Parser<'a> {
     pub span: Span,
     /// the span of the previous token:
     pub prev_span: Span,
-    pub cfg: CrateConfig,
     /// the previous token kind
     prev_token_kind: PrevTokenKind,
     lookahead_buffer: LookaheadBuffer,
@@ -358,11 +357,7 @@ impl From<P<Expr>> for LhsExpr {
 }
 
 impl<'a> Parser<'a> {
-    pub fn new(sess: &'a ParseSess,
-               cfg: ast::CrateConfig,
-               mut rdr: Box<Reader+'a>)
-               -> Parser<'a>
-    {
+    pub fn new(sess: &'a ParseSess, mut rdr: Box<Reader+'a>) -> Self {
         let tok0 = rdr.real_token();
         let span = tok0.sp;
         let mut directory = match span {
@@ -374,7 +369,6 @@ impl<'a> Parser<'a> {
         Parser {
             reader: rdr,
             sess: sess,
-            cfg: cfg,
             token: tok0.tok,
             span: span,
             prev_span: span,
@@ -5328,7 +5322,6 @@ impl<'a> Parser<'a> {
     fn parse_item_mod(&mut self, outer_attrs: &[Attribute]) -> PResult<'a, ItemInfo> {
         let (in_cfg, outer_attrs) = {
             let mut strip_unconfigured = ::config::StripUnconfigured {
-                config: &self.cfg,
                 sess: self.sess,
                 should_test: false, // irrelevant
                 features: None, // don't perform gated feature checking
@@ -5496,12 +5489,7 @@ impl<'a> Parser<'a> {
         included_mod_stack.push(path.clone());
         drop(included_mod_stack);
 
-        let mut p0 = new_sub_parser_from_file(self.sess,
-                                              self.cfg.clone(),
-                                              &path,
-                                              owns_directory,
-                                              Some(name),
-                                              id_sp);
+        let mut p0 = new_sub_parser_from_file(self.sess, &path, owns_directory, Some(name), id_sp);
         let mod_inner_lo = p0.span.lo;
         let mod_attrs = p0.parse_inner_attributes()?;
         let m0 = p0.parse_mod_items(&token::Eof, mod_inner_lo)?;
@@ -6195,7 +6183,6 @@ impl<'a> Parser<'a> {
         Ok(ast::Crate {
             attrs: self.parse_inner_attributes()?,
             module: self.parse_mod_items(&token::Eof, lo)?,
-            config: self.cfg.clone(),
             span: mk_sp(lo, self.span.lo),
             exported_macros: Vec::new(),
         })
diff --git a/src/libsyntax/test.rs b/src/libsyntax/test.rs
index 8faad77859e..fdc1f45623d 100644
--- a/src/libsyntax/test.rs
+++ b/src/libsyntax/test.rs
@@ -274,7 +274,7 @@ fn generate_test_harness(sess: &ParseSess,
     let mut cx: TestCtxt = TestCtxt {
         sess: sess,
         span_diagnostic: sd,
-        ext_cx: ExtCtxt::new(sess, vec![], ExpansionConfig::default("test".to_string()), resolver),
+        ext_cx: ExtCtxt::new(sess, ExpansionConfig::default("test".to_string()), resolver),
         path: Vec::new(),
         testfns: Vec::new(),
         reexport_test_harness_main: reexport_test_harness_main,
diff --git a/src/libsyntax/tokenstream.rs b/src/libsyntax/tokenstream.rs
index f22f920a7fa..9e644e59e86 100644
--- a/src/libsyntax/tokenstream.rs
+++ b/src/libsyntax/tokenstream.rs
@@ -220,7 +220,7 @@ impl TokenTree {
                                                          None,
                                                          tts.iter().cloned().collect(),
                                                          true);
-        macro_parser::parse(cx.parse_sess(), cx.cfg(), arg_rdr, mtch)
+        macro_parser::parse(cx.parse_sess(), arg_rdr, mtch)
     }
 
     /// Check if this TokenTree is equal to the other, regardless of span information.
diff --git a/src/libsyntax/util/parser_testing.rs b/src/libsyntax/util/parser_testing.rs
index f59428bf536..76d3f2a063c 100644
--- a/src/libsyntax/util/parser_testing.rs
+++ b/src/libsyntax/util/parser_testing.rs
@@ -25,10 +25,7 @@ pub fn string_to_tts(source_str: String) -> Vec<tokenstream::TokenTree> {
 
 /// Map string to parser (via tts)
 pub fn string_to_parser<'a>(ps: &'a ParseSess, source_str: String) -> Parser<'a> {
-    new_parser_from_source_str(ps,
-                               Vec::new(),
-                               "bogofile".to_string(),
-                               source_str)
+    new_parser_from_source_str(ps, "bogofile".to_string(), source_str)
 }
 
 fn with_error_checking_parse<'a, T, F>(s: String, ps: &'a ParseSess, f: F) -> T where
diff --git a/src/libsyntax_ext/asm.rs b/src/libsyntax_ext/asm.rs
index 1c97099d387..24c515e5028 100644
--- a/src/libsyntax_ext/asm.rs
+++ b/src/libsyntax_ext/asm.rs
@@ -107,7 +107,7 @@ pub fn expand_asm<'cx>(cx: &'cx mut ExtCtxt,
                 if p2.token != token::Eof {
                     let mut extra_tts = panictry!(p2.parse_all_token_trees());
                     extra_tts.extend(tts[first_colon..].iter().cloned());
-                    p = parse::tts_to_parser(cx.parse_sess, extra_tts, cx.cfg().clone());
+                    p = parse::tts_to_parser(cx.parse_sess, extra_tts);
                 }
 
                 asm = s;
diff --git a/src/libsyntax_ext/cfg.rs b/src/libsyntax_ext/cfg.rs
index 169ef9ab7d6..98da49545f9 100644
--- a/src/libsyntax_ext/cfg.rs
+++ b/src/libsyntax_ext/cfg.rs
@@ -32,6 +32,6 @@ pub fn expand_cfg<'cx>(cx: &mut ExtCtxt,
         return DummyResult::expr(sp);
     }
 
-    let matches_cfg = attr::cfg_matches(&cx.cfg, &cfg, cx.parse_sess, cx.ecfg.features);
+    let matches_cfg = attr::cfg_matches(&cfg, cx.parse_sess, cx.ecfg.features);
     MacEager::expr(cx.expr_bool(sp, matches_cfg))
 }
diff --git a/src/libsyntax_ext/proc_macro_registrar.rs b/src/libsyntax_ext/proc_macro_registrar.rs
index b96fb08e59e..f49a5f0e070 100644
--- a/src/libsyntax_ext/proc_macro_registrar.rs
+++ b/src/libsyntax_ext/proc_macro_registrar.rs
@@ -47,7 +47,7 @@ pub fn modify(sess: &ParseSess,
               handler: &errors::Handler,
               features: &Features) -> ast::Crate {
     let ecfg = ExpansionConfig::default("proc_macro".to_string());
-    let mut cx = ExtCtxt::new(sess, Vec::new(), ecfg, resolver);
+    let mut cx = ExtCtxt::new(sess, ecfg, resolver);
 
     let mut collect = CollectCustomDerives {
         derives: Vec::new(),
diff --git a/src/test/compile-fail-fulldeps/auxiliary/macro_crate_test.rs b/src/test/compile-fail-fulldeps/auxiliary/macro_crate_test.rs
index 2041abcf82c..60697cc8b6a 100644
--- a/src/test/compile-fail-fulldeps/auxiliary/macro_crate_test.rs
+++ b/src/test/compile-fail-fulldeps/auxiliary/macro_crate_test.rs
@@ -56,8 +56,7 @@ fn expand_make_a_1(cx: &mut ExtCtxt, sp: Span, tts: &[TokenTree])
 fn expand_identity(cx: &mut ExtCtxt, _span: Span, tts: &[TokenTree])
                    -> Box<MacResult+'static> {
     // Parse an expression and emit it unchanged.
-    let mut parser = parse::new_parser_from_tts(cx.parse_sess(),
-        cx.cfg().clone(), tts.to_vec());
+    let mut parser = parse::new_parser_from_tts(cx.parse_sess(), tts.to_vec());
     let expr = parser.parse_expr().unwrap();
     MacEager::expr(quote_expr!(&mut *cx, $expr))
 }
diff --git a/src/test/compile-fail-fulldeps/qquote.rs b/src/test/compile-fail-fulldeps/qquote.rs
index 3e5d17e2ffb..4a7033d44b8 100644
--- a/src/test/compile-fail-fulldeps/qquote.rs
+++ b/src/test/compile-fail-fulldeps/qquote.rs
@@ -24,7 +24,7 @@ fn main() {
     let ps = syntax::parse::ParseSess::new();
     let mut resolver = syntax::ext::base::DummyResolver;
     let mut cx = syntax::ext::base::ExtCtxt::new(
-        &ps, vec![],
+        &ps,
         syntax::ext::expand::ExpansionConfig::default("qquote".to_string()),
         &mut resolver);
     cx.bt_push(syntax::codemap::ExpnInfo {
diff --git a/src/test/run-fail-fulldeps/qquote.rs b/src/test/run-fail-fulldeps/qquote.rs
index 1458583ff58..d2a16ac7507 100644
--- a/src/test/run-fail-fulldeps/qquote.rs
+++ b/src/test/run-fail-fulldeps/qquote.rs
@@ -27,7 +27,7 @@ fn main() {
     let ps = syntax::parse::ParseSess::new();
     let mut resolver = syntax::ext::base::DummyResolver;
     let mut cx = syntax::ext::base::ExtCtxt::new(
-        &ps, vec![],
+        &ps,
         syntax::ext::expand::ExpansionConfig::default("qquote".to_string()),
         &mut resolver);
     cx.bt_push(syntax::codemap::ExpnInfo {
diff --git a/src/test/run-make/issue-19371/foo.rs b/src/test/run-make/issue-19371/foo.rs
index 35043bdaddf..ed127b017b6 100644
--- a/src/test/run-make/issue-19371/foo.rs
+++ b/src/test/run-make/issue-19371/foo.rs
@@ -67,12 +67,6 @@ fn compile(code: String, output: PathBuf, sysroot: PathBuf) {
     let (sess, cstore) = basic_sess(sysroot);
     let cfg = build_configuration(&sess, vec![]);
     let control = CompileController::basic();
-
-    compile_input(&sess, &cstore,
-            cfg,
-            &Input::Str { name: anon_src(), input: code },
-            &None,
-            &Some(output),
-            None,
-            &control);
+    let input = Input::Str { name: anon_src(), input: code };
+    compile_input(&sess, &cstore, &input, &None, &Some(output), None, &control);
 }
diff --git a/src/test/run-pass-fulldeps/ast_stmt_expr_attr.rs b/src/test/run-pass-fulldeps/ast_stmt_expr_attr.rs
index 64747002a65..a41b34f6a53 100644
--- a/src/test/run-pass-fulldeps/ast_stmt_expr_attr.rs
+++ b/src/test/run-pass-fulldeps/ast_stmt_expr_attr.rs
@@ -31,10 +31,7 @@ use std::fmt;
 // Copied out of syntax::util::parser_testing
 
 pub fn string_to_parser<'a>(ps: &'a ParseSess, source_str: String) -> Parser<'a> {
-    new_parser_from_source_str(ps,
-                               Vec::new(),
-                               "bogofile".to_string(),
-                               source_str)
+    new_parser_from_source_str(ps, "bogofile".to_string(), source_str)
 }
 
 fn with_error_checking_parse<'a, T, F>(s: String, ps: &'a ParseSess, f: F) -> PResult<'a, T> where
diff --git a/src/test/run-pass-fulldeps/auxiliary/macro_crate_test.rs b/src/test/run-pass-fulldeps/auxiliary/macro_crate_test.rs
index 2c814a5433b..15ec0ccae8f 100644
--- a/src/test/run-pass-fulldeps/auxiliary/macro_crate_test.rs
+++ b/src/test/run-pass-fulldeps/auxiliary/macro_crate_test.rs
@@ -60,7 +60,7 @@ fn expand_make_a_1(cx: &mut ExtCtxt, sp: Span, tts: &[TokenTree]) -> Box<MacResu
 // See Issue #15750
 fn expand_identity(cx: &mut ExtCtxt, _span: Span, tts: &[TokenTree]) -> Box<MacResult + 'static> {
     // Parse an expression and emit it unchanged.
-    let mut parser = parse::new_parser_from_tts(cx.parse_sess(), cx.cfg().clone(), tts.to_vec());
+    let mut parser = parse::new_parser_from_tts(cx.parse_sess(), tts.to_vec());
     let expr = parser.parse_expr().unwrap();
     MacEager::expr(quote_expr!(&mut *cx, $expr))
 }
diff --git a/src/test/run-pass-fulldeps/compiler-calls.rs b/src/test/run-pass-fulldeps/compiler-calls.rs
index 35e9f3f5c8d..4a397621ceb 100644
--- a/src/test/run-pass-fulldeps/compiler-calls.rs
+++ b/src/test/run-pass-fulldeps/compiler-calls.rs
@@ -47,7 +47,6 @@ impl<'a> CompilerCalls<'a> for TestCalls {
     fn late_callback(&mut self,
                      _: &getopts::Matches,
                      _: &Session,
-                     _: &ast::CrateConfig,
                      _: &Input,
                      _: &Option<PathBuf>,
                      _: &Option<PathBuf>)
diff --git a/src/test/run-pass-fulldeps/qquote.rs b/src/test/run-pass-fulldeps/qquote.rs
index 2a53a62a5ab..7c0c24163fe 100644
--- a/src/test/run-pass-fulldeps/qquote.rs
+++ b/src/test/run-pass-fulldeps/qquote.rs
@@ -23,7 +23,7 @@ fn main() {
     let ps = syntax::parse::ParseSess::new();
     let mut resolver = syntax::ext::base::DummyResolver;
     let mut cx = syntax::ext::base::ExtCtxt::new(
-        &ps, vec![],
+        &ps,
         syntax::ext::expand::ExpansionConfig::default("qquote".to_string()),
         &mut resolver);
     cx.bt_push(syntax::codemap::ExpnInfo {