auto merge of #8362 : sfackler/rust/env, r=alexcrichton

env! aborts compilation of the specified environment variable is not
defined and takes an optional second argument containing a custom
error message. option_env! creates an Option<&'static str> containing
the value of the environment variable.

There are no run-pass tests that check the behavior when the environment
variable is defined since the test framework doesn't support setting
environment variables at compile time as opposed to runtime. However,
both env! and option_env! are used inside of rustc itself, which should
act as a sufficient test.

Fixes #2248.

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 dc20994b49f..1e696451701 100644
--- a/src/libsyntax/ext/base.rs
+++ b/src/libsyntax/ext/base.rs
@@ -148,7 +148,9 @@ 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"),
@@ -313,7 +315,7 @@ 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,
@@ -538,8 +540,8 @@ 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();
@@ -551,8 +553,8 @@ 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) -> ! {