Remove preconditions from libraries

Closes #1805

4 files changed, 5 insertions, 23 deletions

diff --git a/src/libstd/fs.rs b/src/libstd/fs.rs
index 947942e20d8..30abbb1e70a 100644
--- a/src/libstd/fs.rs
+++ b/src/libstd/fs.rs
@@ -107,12 +107,11 @@ Connects a vector of path segments into a single path.
 
 Inserts path separators as needed.
 */
-fn connect_many(paths: [path]) : vec::is_not_empty(paths) -> path {
+fn connect_many(paths: [path]) -> path {
     ret if vec::len(paths) == 1u {
         paths[0]
     } else {
         let rest = vec::slice(paths, 1u, vec::len(paths));
-        check vec::is_not_empty(rest);
         connect(paths[0], connect_many(rest))
     }
 }
diff --git a/src/libstd/list.rs b/src/libstd/list.rs
index be6ce7338a3..3c2d6988587 100644
--- a/src/libstd/list.rs
+++ b/src/libstd/list.rs
@@ -140,11 +140,8 @@ Function: head
 
 Returns the first element of a list
 */
-pure fn head<T: copy>(ls: list<T>) : is_not_empty(ls) -> T {
-    alt ls {
-        cons(hd, _) { ret hd; }
-        nil { fail "list empty" }
-    }
+pure fn head<T: copy>(ls: list<T>) -> T {
+    alt check ls { cons(hd, _) { hd } }
 }
 
 /*
@@ -205,15 +202,12 @@ mod tests {
     fn test_from_vec() {
         let l = from_vec([0, 1, 2]);
 
-        check is_not_empty(l);
         assert (head(l) == 0);
 
         let tail_l = tail(l);
-        check is_not_empty(tail_l);
         assert (head(tail_l) == 1);
 
         let tail_tail_l = tail(tail_l);
-        check is_not_empty(tail_tail_l);
         assert (head(tail_tail_l) == 2);
     }
 
@@ -227,15 +221,12 @@ mod tests {
     fn test_from_vec_mut() {
         let l = from_vec([mutable 0, 1, 2]);
 
-        check is_not_empty(l);
         assert (head(l) == 0);
 
         let tail_l = tail(l);
-        check is_not_empty(tail_l);
         assert (head(tail_l) == 1);
 
         let tail_tail_l = tail(tail_l);
-        check is_not_empty(tail_tail_l);
         assert (head(tail_tail_l) == 2);
     }
 
diff --git a/src/libstd/sort.rs b/src/libstd/sort.rs
index 8c4ac924055..cceff6d66bb 100644
--- a/src/libstd/sort.rs
+++ b/src/libstd/sort.rs
@@ -252,8 +252,6 @@ mod test_qsort {
 
         let immut_names = vec::from_mut(names);
 
-        // Silly, but what else can we do?
-        check (vec::same_length(expected, immut_names));
         let pairs = vec::zip(expected, immut_names);
         for (a, b) in pairs { #debug("%d %d", a, b); assert (a == b); }
     }
diff --git a/src/libstd/test.rs b/src/libstd/test.rs
index 9f25916778f..6f39ea14047 100644
--- a/src/libstd/test.rs
+++ b/src/libstd/test.rs
@@ -47,7 +47,6 @@ type test_desc = {
 // The default console test runner. It accepts the command line
 // arguments and a vector of test_descs (generated at compile time).
 fn test_main(args: [str], tests: [test_desc]) {
-    check (vec::is_not_empty(args));
     let opts =
         alt parse_opts(args) {
           either::left(o) { o }
@@ -61,8 +60,7 @@ type test_opts = {filter: option<str>, run_ignored: bool};
 type opt_res = either::t<test_opts, str>;
 
 // Parses command line arguments into test options
-fn parse_opts(args: [str]) : vec::is_not_empty(args) -> opt_res {
-
+fn parse_opts(args: [str]) -> opt_res {
     let args_ = vec::tail(args);
     let opts = [getopts::optflag("ignored")];
     let match =
@@ -407,7 +405,6 @@ mod tests {
     #[test]
     fn first_free_arg_should_be_a_filter() {
         let args = ["progname", "filter"];
-        check (vec::is_not_empty(args));
         let opts = alt parse_opts(args) { either::left(o) { o }
           _ { fail "Malformed arg in first_free_arg_should_be_a_filter"; } };
         assert (str::eq("filter", option::get(opts.filter)));
@@ -416,7 +413,6 @@ mod tests {
     #[test]
     fn parse_ignored_flag() {
         let args = ["progname", "filter", "--ignored"];
-        check (vec::is_not_empty(args));
         let opts = alt parse_opts(args) { either::left(o) { o }
           _ { fail "Malformed arg in parse_ignored_flag"; } };
         assert (opts.run_ignored);
@@ -469,12 +465,10 @@ mod tests {
          "test::ignored_tests_result_in_ignored", "test::parse_ignored_flag",
          "test::sort_tests"];
 
-    check (vec::same_length(expected, filtered));
     let pairs = vec::zip(expected, filtered);
 
-
     for (a, b) in pairs { assert (a == b.name); }
-    }
+}
 }