From bfc9a499c25919b75a87c05beb60e2c76688e7cf Mon Sep 17 00:00:00 2001
From: Graydon Hoare <graydon@mozilla.com>
Date: Fri, 30 Dec 2011 15:26:49 -0800
Subject: [PATCH] Print usage messages to rustc and rustdoc when invoked with
 no args. Close #1394.

---
 src/comp/driver/rustc.rs |  3 +++
 src/rustdoc/rustdoc.rs   | 10 +++++++++-
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/src/comp/driver/rustc.rs b/src/comp/driver/rustc.rs
index aad129b6ac8..7f0ad7da3bb 100644
--- a/src/comp/driver/rustc.rs
+++ b/src/comp/driver/rustc.rs
@@ -61,6 +61,9 @@ fn usage(argv0: str) {
 
 fn main(args: [str]) {
     let args = args, binary = vec::shift(args);
+
+    if vec::len(args) == 0u { usage(binary); ret; }
+
     let match =
         alt getopts::getopts(args, opts()) {
           ok(m) { m }
diff --git a/src/rustdoc/rustdoc.rs b/src/rustdoc/rustdoc.rs
index 055f3e7749d..cfa1fbed676 100755
--- a/src/rustdoc/rustdoc.rs
+++ b/src/rustdoc/rustdoc.rs
@@ -179,9 +179,17 @@ fn doc_header(rd: rustdoc, name: str) {
 *  argv[1]: crate file name",
   args(argv = "Command-line arguments.")
 )]
+
 fn main(argv: [str]) {
-    let sess = @{cm: codemap::new_codemap(), mutable next_id: 0};
+
     let w = io::stdout();
+
+    if vec::len(argv) != 2u {
+        w.write_str(#fmt("usage: %s <input>\n", argv[0]));
+        ret;
+    }
+
+    let sess = @{cm: codemap::new_codemap(), mutable next_id: 0};
     let rd = { ps: pprust::rust_printer(w), w: w };
     doc_header(rd, argv[1]);
     let p = parser::parse_crate_from_source_file(argv[1], [], sess);
-- 
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