Add -Zinput-stats

Emits loc, and node count - before and after expansion.

E.g.,

```
rustc: x86_64-unknown-linux-gnu/stage2/lib/rustlib/x86_64-unknown-linux-gnu/lib/libcore
Lines of code:             32060
Pre-expansion node count:  120205
Post-expansion node count: 482749
```

5 files changed, 218 insertions, 26 deletions

diff --git a/src/librustc/session/config.rs b/src/librustc/session/config.rs
index 2f22f33e39d..808a63982c2 100644
--- a/src/librustc/session/config.rs
+++ b/src/librustc/session/config.rs
@@ -510,7 +510,7 @@ options! {CodegenOptions, CodegenSetter, basic_codegen_options,
         "debug info emission level, 0 = no debug info, 1 = line tables only, \
          2 = full debug info with variable and type information"),
     opt_level: Option<usize> = (None, parse_opt_uint,
-        "Optimize with possible levels 0-3"),
+        "optimize with possible levels 0-3"),
     debug_assertions: Option<bool> = (None, parse_opt_bool,
         "explicitly enable the cfg(debug_assertions) directive"),
 }
@@ -527,6 +527,8 @@ options! {DebuggingOptions, DebuggingSetter, basic_debugging_options,
         "count where LLVM instrs originate"),
     time_llvm_passes: bool = (false, parse_bool,
         "measure time of each LLVM pass"),
+    input_stats: bool = (false, parse_bool,
+        "gather statistics about the input"),
     trans_stats: bool = (false, parse_bool,
         "gather trans statistics"),
     asm_comments: bool = (false, parse_bool,
@@ -544,56 +546,56 @@ options! {DebuggingOptions, DebuggingSetter, basic_debugging_options,
     meta_stats: bool = (false, parse_bool,
         "gather metadata statistics"),
     print_link_args: bool = (false, parse_bool,
-        "Print the arguments passed to the linker"),
+        "print the arguments passed to the linker"),
     gc: bool = (false, parse_bool,
-        "Garbage collect shared data (experimental)"),
+        "garbage collect shared data (experimental)"),
     print_llvm_passes: bool = (false, parse_bool,
-        "Prints the llvm optimization passes being run"),
+        "prints the llvm optimization passes being run"),
     ast_json: bool = (false, parse_bool,
-        "Print the AST as JSON and halt"),
+        "print the AST as JSON and halt"),
     ast_json_noexpand: bool = (false, parse_bool,
-        "Print the pre-expansion AST as JSON and halt"),
+        "print the pre-expansion AST as JSON and halt"),
     ls: bool = (false, parse_bool,
-        "List the symbols defined by a library crate"),
+        "list the symbols defined by a library crate"),
     save_analysis: bool = (false, parse_bool,
-        "Write syntax and type analysis information in addition to normal output"),
+        "write syntax and type analysis information in addition to normal output"),
     print_move_fragments: bool = (false, parse_bool,
-        "Print out move-fragment data for every fn"),
+        "print out move-fragment data for every fn"),
     flowgraph_print_loans: bool = (false, parse_bool,
-        "Include loan analysis data in --unpretty flowgraph output"),
+        "include loan analysis data in --unpretty flowgraph output"),
     flowgraph_print_moves: bool = (false, parse_bool,
-        "Include move analysis data in --unpretty flowgraph output"),
+        "include move analysis data in --unpretty flowgraph output"),
     flowgraph_print_assigns: bool = (false, parse_bool,
-        "Include assignment analysis data in --unpretty flowgraph output"),
+        "include assignment analysis data in --unpretty flowgraph output"),
     flowgraph_print_all: bool = (false, parse_bool,
-        "Include all dataflow analysis data in --unpretty flowgraph output"),
+        "include all dataflow analysis data in --unpretty flowgraph output"),
     print_region_graph: bool = (false, parse_bool,
-         "Prints region inference graph. \
+         "prints region inference graph. \
           Use with RUST_REGION_GRAPH=help for more info"),
     parse_only: bool = (false, parse_bool,
-          "Parse only; do not compile, assemble, or link"),
+          "parse only; do not compile, assemble, or link"),
     no_trans: bool = (false, parse_bool,
-          "Run all passes except translation; no output"),
+          "run all passes except translation; no output"),
     treat_err_as_bug: bool = (false, parse_bool,
-          "Treat all errors that occur as bugs"),
+          "treat all errors that occur as bugs"),
     no_analysis: bool = (false, parse_bool,
-          "Parse and expand the source, but run no analysis"),
+          "parse and expand the source, but run no analysis"),
     extra_plugins: Vec<String> = (Vec::new(), parse_list,
         "load extra plugins"),
     unstable_options: bool = (false, parse_bool,
-          "Adds unstable command line options to rustc interface"),
+          "adds unstable command line options to rustc interface"),
     print_enum_sizes: bool = (false, parse_bool,
-          "Print the size of enums and their variants"),
+          "print the size of enums and their variants"),
     force_overflow_checks: Option<bool> = (None, parse_opt_bool,
-          "Force overflow checks on or off"),
+          "force overflow checks on or off"),
     force_dropflag_checks: Option<bool> = (None, parse_opt_bool,
-          "Force drop flag checks on or off"),
+          "force drop flag checks on or off"),
     trace_macros: bool = (false, parse_bool,
-          "For every macro invocation, print its name and arguments"),
+          "for every macro invocation, print its name and arguments"),
     enable_nonzeroing_move_hints: bool = (false, parse_bool,
-          "Force nonzeroing move optimization on"),
+          "force nonzeroing move optimization on"),
     keep_mtwt_tables: bool = (false, parse_bool,
-          "Don't clear the resolution tables after analysis"),
+          "don't clear the resolution tables after analysis"),
 }
 
 pub fn default_lib_output() -> CrateType {
diff --git a/src/librustc_driver/driver.rs b/src/librustc_driver/driver.rs
index ba9bf4bac7d..def8d3bc404 100644
--- a/src/librustc_driver/driver.rs
+++ b/src/librustc_driver/driver.rs
@@ -52,6 +52,8 @@ use syntax::feature_gate::UnstableFeatures;
 use syntax::fold::Folder;
 use syntax::parse;
 use syntax::parse::token;
+use syntax::util::node_count::NodeCounter;
+use syntax::visit;
 use syntax;
 
 pub fn compile_input(sess: Session,
@@ -398,6 +400,11 @@ pub fn phase_1_parse_input(sess: &Session, cfg: ast::CrateConfig, input: &Input)
         println!("{}", json::as_json(&krate));
     }
 
+    if sess.opts.debugging_opts.input_stats {
+        println!("Lines of code:             {}", sess.codemap().count_lines());
+        println!("Pre-expansion node count:  {}", count_nodes(&krate));
+    }
+
     if let Some(ref s) = sess.opts.show_span {
         syntax::show_span::run(sess.diagnostic(), s, &krate);
     }
@@ -405,6 +412,12 @@ pub fn phase_1_parse_input(sess: &Session, cfg: ast::CrateConfig, input: &Input)
     krate
 }
 
+fn count_nodes(krate: &ast::Crate) -> usize {
+    let mut counter = NodeCounter::new();
+    visit::walk_crate(&mut counter, krate);
+    counter.count
+}
+
 // For continuing compilation after a parsed crate has been
 // modified
 
@@ -606,6 +619,10 @@ pub fn phase_2_configure_and_expand(sess: &Session,
         sess.abort_if_errors();
     });
 
+    if sess.opts.debugging_opts.input_stats {
+        println!("Post-expansion node count: {}", count_nodes(&krate));
+    }
+
     Some(krate)
 }
 
diff --git a/src/libsyntax/codemap.rs b/src/libsyntax/codemap.rs
index a73fd4534c9..db011265c73 100644
--- a/src/libsyntax/codemap.rs
+++ b/src/libsyntax/codemap.rs
@@ -559,6 +559,10 @@ impl FileMap {
     pub fn is_imported(&self) -> bool {
         self.src.is_none()
     }
+
+    fn count_lines(&self) -> usize {
+        self.lines.borrow().len()
+    }
 }
 
 /// An abstraction over the fs operations used by the Parser.
@@ -1021,6 +1025,10 @@ impl CodeMap {
         debug!("span_allows_unstable? {}", allows_unstable);
         allows_unstable
     }
+
+    pub fn count_lines(&self) -> usize {
+        self.files.borrow().iter().fold(0, |a, f| a + f.count_lines())
+    }
 }
 
 // _____________________________________________________________________________
diff --git a/src/libsyntax/lib.rs b/src/libsyntax/lib.rs
index 8b001f2419c..524ac655d88 100644
--- a/src/libsyntax/lib.rs
+++ b/src/libsyntax/lib.rs
@@ -62,10 +62,11 @@ macro_rules! panictry {
 
 pub mod util {
     pub mod interner;
+    pub mod node_count;
+    pub mod parser;
     #[cfg(test)]
     pub mod parser_testing;
     pub mod small_vector;
-    pub mod parser;
 }
 
 pub mod diagnostics {
diff --git a/src/libsyntax/util/node_count.rs b/src/libsyntax/util/node_count.rs
new file mode 100644
index 00000000000..e692ec4452c
--- /dev/null
+++ b/src/libsyntax/util/node_count.rs
@@ -0,0 +1,164 @@
+// Copyright 2015 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.
+
+// Simply gives a rought count of the number of nodes in an AST.
+
+use visit::*;
+use ast::*;
+use codemap::Span;
+
+pub struct NodeCounter {
+    pub count: usize,
+}
+
+impl NodeCounter {
+    pub fn new() -> NodeCounter {
+        NodeCounter {
+            count: 0,
+        }
+    }
+}
+
+impl<'v> Visitor<'v> for NodeCounter {
+    fn visit_ident(&mut self, span: Span, ident: Ident) {
+        self.count += 1;
+        walk_ident(self, span, ident);
+    }
+    fn visit_mod(&mut self, m: &'v Mod, _s: Span, _n: NodeId) {
+        self.count += 1;
+        walk_mod(self, m)
+    }
+    fn visit_foreign_item(&mut self, i: &'v ForeignItem) {
+        self.count += 1;
+        walk_foreign_item(self, i)
+    }
+    fn visit_item(&mut self, i: &'v Item) {
+        self.count += 1;
+        walk_item(self, i)
+    }
+    fn visit_local(&mut self, l: &'v Local) {
+        self.count += 1;
+        walk_local(self, l)
+    }
+    fn visit_block(&mut self, b: &'v Block) {
+        self.count += 1;
+        walk_block(self, b)
+    }
+    fn visit_stmt(&mut self, s: &'v Stmt) {
+        self.count += 1;
+        walk_stmt(self, s)
+    }
+    fn visit_arm(&mut self, a: &'v Arm) {
+        self.count += 1;
+        walk_arm(self, a)
+    }
+    fn visit_pat(&mut self, p: &'v Pat) {
+        self.count += 1;
+        walk_pat(self, p)
+    }
+    fn visit_decl(&mut self, d: &'v Decl) {
+        self.count += 1;
+        walk_decl(self, d)
+    }
+    fn visit_expr(&mut self, ex: &'v Expr) {
+        self.count += 1;
+        walk_expr(self, ex)
+    }
+    fn visit_ty(&mut self, t: &'v Ty) {
+        self.count += 1;
+        walk_ty(self, t)
+    }
+    fn visit_generics(&mut self, g: &'v Generics) {
+        self.count += 1;
+        walk_generics(self, g)
+    }
+    fn visit_fn(&mut self, fk: FnKind<'v>, fd: &'v FnDecl, b: &'v Block, s: Span, _: NodeId) {
+        self.count += 1;
+        walk_fn(self, fk, fd, b, s)
+    }
+    fn visit_trait_item(&mut self, ti: &'v TraitItem) {
+        self.count += 1;
+        walk_trait_item(self, ti)
+    }
+    fn visit_impl_item(&mut self, ii: &'v ImplItem) {
+        self.count += 1;
+        walk_impl_item(self, ii)
+    }
+    fn visit_trait_ref(&mut self, t: &'v TraitRef) {
+        self.count += 1;
+        walk_trait_ref(self, t)
+    }
+    fn visit_ty_param_bound(&mut self, bounds: &'v TyParamBound) {
+        self.count += 1;
+        walk_ty_param_bound(self, bounds)
+    }
+    fn visit_poly_trait_ref(&mut self, t: &'v PolyTraitRef, m: &'v TraitBoundModifier) {
+        self.count += 1;
+        walk_poly_trait_ref(self, t, m)
+    }
+    fn visit_variant_data(&mut self, s: &'v VariantData, _: Ident,
+                        _: &'v Generics, _: NodeId, _: Span) {
+        self.count += 1;
+        walk_struct_def(self, s)
+    }
+    fn visit_struct_field(&mut self, s: &'v StructField) {
+        self.count += 1;
+        walk_struct_field(self, s)
+    }
+    fn visit_enum_def(&mut self, enum_definition: &'v EnumDef,
+                      generics: &'v Generics, item_id: NodeId, _: Span) {
+        self.count += 1;
+        walk_enum_def(self, enum_definition, generics, item_id)
+    }
+    fn visit_variant(&mut self, v: &'v Variant, g: &'v Generics, item_id: NodeId) {
+        self.count += 1;
+        walk_variant(self, v, g, item_id)
+    }
+    fn visit_lifetime(&mut self, lifetime: &'v Lifetime) {
+        self.count += 1;
+        walk_lifetime(self, lifetime)
+    }
+    fn visit_lifetime_def(&mut self, lifetime: &'v LifetimeDef) {
+        self.count += 1;
+        walk_lifetime_def(self, lifetime)
+    }
+    fn visit_explicit_self(&mut self, es: &'v ExplicitSelf) {
+        self.count += 1;
+        walk_explicit_self(self, es)
+    }
+    fn visit_mac(&mut self, _mac: &'v Mac) {
+        self.count += 1;
+        walk_mac(self, _mac)
+    }
+    fn visit_path(&mut self, path: &'v Path, _id: NodeId) {
+        self.count += 1;
+        walk_path(self, path)
+    }
+    fn visit_path_list_item(&mut self, prefix: &'v Path, item: &'v PathListItem) {
+        self.count += 1;
+        walk_path_list_item(self, prefix, item)
+    }
+    fn visit_path_parameters(&mut self, path_span: Span, path_parameters: &'v PathParameters) {
+        self.count += 1;
+        walk_path_parameters(self, path_span, path_parameters)
+    }
+    fn visit_assoc_type_binding(&mut self, type_binding: &'v TypeBinding) {
+        self.count += 1;
+        walk_assoc_type_binding(self, type_binding)
+    }
+    fn visit_attribute(&mut self, _attr: &'v Attribute) {
+        self.count += 1;
+    }
+    fn visit_macro_def(&mut self, macro_def: &'v MacroDef) {
+        self.count += 1;
+        walk_macro_def(self, macro_def)
+    }
+
+}