4 files changed, 37 insertions, 17 deletions
diff --git a/src/libsyntax/ext/asm.rs b/src/libsyntax/ext/asm.rs
index ee0ec664e1b..b5d97427baf 100644
--- a/src/libsyntax/ext/asm.rs
+++ b/src/libsyntax/ext/asm.rs
@@ -1,4 +1,4 @@
-// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
+// Copyright 2012-2013 The Rust Project Developers. See the COPYRIGHT
 // file at the top-level directory of this distribution and at
 // http://rust-lang.org/COPYRIGHT.
 //
@@ -59,7 +59,7 @@ pub fn expand_asm(cx: @ExtCtxt, sp: span, tts: &[ast::token_tree])
         match state {
             Asm => {
                 asm = expr_to_str(cx, p.parse_expr(),
-                                  ~"inline assembly must be a string literal.");
+                                  "inline assembly must be a string literal.");
             }
             Outputs => {
                 while *p.token != token::EOF &&
diff --git a/src/libsyntax/ext/base.rs b/src/libsyntax/ext/base.rs
index efaf6b8e001..1ba32442d5e 100644
--- a/src/libsyntax/ext/base.rs
+++ b/src/libsyntax/ext/base.rs
@@ -146,7 +146,9 @@ pub fn syntax_expander_table() -> SyntaxEnv {
         intern(&"auto_decode"),
         @SE(ItemDecorator(ext::auto_encode::expand_auto_decode)));
     syntax_expanders.insert(intern(&"env"),
-                            builtin_normal_tt(ext::env::expand_syntax_ext));
+                            builtin_normal_tt(ext::env::expand_env));
+    syntax_expanders.insert(intern(&"option_env"),
+                            builtin_normal_tt(ext::env::expand_option_env));
     syntax_expanders.insert(intern("bytes"),
                             builtin_normal_tt(ext::bytes::expand_syntax_ext));
     syntax_expanders.insert(intern("concat_idents"),
@@ -311,7 +313,7 @@ impl ExtCtxt {
     }
 }
 
-pub fn expr_to_str(cx: @ExtCtxt, expr: @ast::expr, err_msg: ~str) -> @str {
+pub fn expr_to_str(cx: @ExtCtxt, expr: @ast::expr, err_msg: &str) -> @str {
     match expr.node {
       ast::expr_lit(l) => match l.node {
         ast::lit_str(s) => s,
@@ -536,8 +538,8 @@ mod test {
         a.insert (@"abc",@15);
         let m = MapChain::new(~a);
         m.insert (@"def",@16);
-        // FIXME: #4492 (ICE)  assert_eq!(m.find(&@"abc"),Some(@15));
-        //  ....               assert_eq!(m.find(&@"def"),Some(@16));
+        assert_eq!(m.find(&@"abc"),Some(@15));
+        assert_eq!(m.find(&@"def"),Some(@16));
         assert_eq!(*(m.find(&@"abc").unwrap()),15);
         assert_eq!(*(m.find(&@"def").unwrap()),16);
         let n = m.push_frame();
@@ -549,8 +551,8 @@ mod test {
         assert_eq!(*(n.find(&@"abc").unwrap()),15);
         assert_eq!(*(n.find(&@"def").unwrap()),17);
         // ... but m still has the old ones
-        // FIXME: #4492: assert_eq!(m.find(&@"abc"),Some(@15));
-        // FIXME: #4492: assert_eq!(m.find(&@"def"),Some(@16));
+        assert_eq!(m.find(&@"abc"),Some(@15));
+        assert_eq!(m.find(&@"def"),Some(@16));
         assert_eq!(*(m.find(&@"abc").unwrap()),15);
         assert_eq!(*(m.find(&@"def").unwrap()),16);
     }
diff --git a/src/libsyntax/ext/env.rs b/src/libsyntax/ext/env.rs
index a6cb6155878..c9e01b0f0d5 100644
--- a/src/libsyntax/ext/env.rs
+++ b/src/libsyntax/ext/env.rs
@@ -1,4 +1,4 @@
-// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
+// Copyright 2012-2013 The Rust Project Developers. See the COPYRIGHT
 // file at the top-level directory of this distribution and at
 // http://rust-lang.org/COPYRIGHT.
 //
@@ -22,17 +22,35 @@ use ext::build::AstBuilder;
 
 use std::os;
 
-pub fn expand_syntax_ext(cx: @ExtCtxt, sp: span, tts: &[ast::token_tree])
+pub fn expand_option_env(ext_cx: @ExtCtxt, sp: span, tts: &[ast::token_tree])
     -> base::MacResult {
+    let var = get_single_str_from_tts(ext_cx, sp, tts, "option_env!");
 
-    let var = get_single_str_from_tts(cx, sp, tts, "env!");
+    let e = match os::getenv(var) {
+      None => quote_expr!(::std::option::None),
+      Some(s) => quote_expr!(::std::option::Some($s))
+    };
+    MRExpr(e)
+}
 
-    // FIXME (#2248): if this was more thorough it would manufacture an
-    // Option<str> rather than just an maybe-empty string.
+pub fn expand_env(ext_cx: @ExtCtxt, sp: span, tts: &[ast::token_tree])
+    -> base::MacResult {
+    let exprs = get_exprs_from_tts(ext_cx, sp, tts);
+
+    if exprs.len() == 0 {
+        ext_cx.span_fatal(sp, "env! takes 1 or 2 arguments");
+    }
+
+    let var = expr_to_str(ext_cx, exprs[0], "expected string literal");
+    let msg = match exprs.len() {
+        1 => fmt!("Environment variable %s not defined", var).to_managed(),
+        2 => expr_to_str(ext_cx, exprs[1], "expected string literal"),
+        _ => ext_cx.span_fatal(sp, "env! takes 1 or 2 arguments")
+    };
 
     let e = match os::getenv(var) {
-      None => cx.expr_str(sp, @""),
-      Some(s) => cx.expr_str(sp, s.to_managed())
+        None => ext_cx.span_fatal(sp, msg),
+        Some(s) => ext_cx.expr_str(sp, s.to_managed())
     };
     MRExpr(e)
 }
diff --git a/src/libsyntax/ext/fmt.rs b/src/libsyntax/ext/fmt.rs
index 2dbf6887a21..008545c9729 100644
--- a/src/libsyntax/ext/fmt.rs
+++ b/src/libsyntax/ext/fmt.rs
@@ -1,4 +1,4 @@
-// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
+// Copyright 2012-2013 The Rust Project Developers. See the COPYRIGHT
 // file at the top-level directory of this distribution and at
 // http://rust-lang.org/COPYRIGHT.
 //
@@ -32,7 +32,7 @@ pub fn expand_syntax_ext(cx: @ExtCtxt, sp: span, tts: &[ast::token_tree])
     }
     let fmt =
         expr_to_str(cx, args[0],
-                    ~"first argument to fmt! must be a string literal.");
+                    "first argument to fmt! must be a string literal.");
     let fmtspan = args[0].span;
     debug!("Format string: %s", fmt);
     fn parse_fmt_err_(cx: @ExtCtxt, sp: span, msg: &str) -> ! {