Add backtraces for syntax problems.

3 files changed, 60 insertions, 64 deletions

diff --git a/src/comp/syntax/ext/base.rs b/src/comp/syntax/ext/base.rs
index fd37b6c2d3c..5aad9c5cd14 100644
--- a/src/comp/syntax/ext/base.rs
+++ b/src/comp/syntax/ext/base.rs
@@ -32,41 +32,46 @@ fn syntax_expander_table() -> hashmap[str, syntax_extension] {
     ret syntax_expanders;
 }
 
-type span_msg_fn = fn(span, str) -> !  ;
-type msg_fn = fn(str) -> !  ;
+obj ext_ctxt(sess: @session, crate_file_name_hack: str, 
+             mutable backtrace: span[]) {
+    fn crate_file_name() -> str { ret crate_file_name_hack; }
 
-type next_id_fn = fn() -> ast::node_id ;
-
-
-// Provides a limited set of services necessary for syntax extensions
-// to do their thing
-type ext_ctxt =
-    {crate_file_name_hack: str,
-     span_fatal: span_msg_fn,
-     span_unimpl: span_msg_fn,
-     span_bug: span_msg_fn,
-     bug: msg_fn,
-     next_id: next_id_fn};
+    fn print_backtrace() {
+        for sp: span in backtrace {
+            sess.span_note(sp, "(while expanding this)")
+        }
+    }
+    
+    fn bt_push(sp: span) { backtrace += ~[sp]; }
+    fn bt_pop() { ivec::pop(backtrace); }
 
-fn mk_ctxt(sess: &session) -> ext_ctxt {
-    fn ext_span_fatal_(sess: &session, sp: span, msg: str) -> ! {
+    fn span_fatal(sp: span, msg: str) -> ! {
+        self.print_backtrace();
+        sess.span_fatal(sp, msg);
+    }
+    fn span_err(sp: span, msg: str) {
+        self.print_backtrace();
         sess.span_err(sp, msg);
-        fail;
     }
-    let ext_span_fatal = bind ext_span_fatal_(sess, _, _);
-    fn ext_span_unimpl_(sess: &session, sp: span, msg: str) -> ! {
-        sess.span_err(sp, "unimplemented " + msg);
-        fail;
+    fn span_unimpl(sp:span, msg: str) -> ! {
+        self.print_backtrace();
+        sess.span_unimpl(sp, msg);
     }
-    let ext_span_bug = bind ext_span_bug_(sess, _, _);
-    fn ext_span_bug_(sess: &session, sp: span, msg: str) -> ! {
-        sess.span_bug(sp, msg);
+    fn span_bug(sp:span, msg: str) -> ! {
+        self.print_backtrace();
+        sess.span_bug(sp, msg); 
+    }
+    fn bug(msg: str) -> ! {
+        self.print_backtrace();
+        sess.bug(msg);
+    }
+    fn next_id() -> ast::node_id {
+        ret sess.next_node_id();
     }
-    let ext_span_unimpl = bind ext_span_unimpl_(sess, _, _);
-    fn ext_bug_(sess: &session, msg: str) -> ! { sess.bug(msg); }
-    let ext_bug = bind ext_bug_(sess, _);
 
+}
 
+fn mk_ctxt(sess: &session) -> ext_ctxt {
     // FIXME: Some extensions work by building ASTs with paths to functions
     // they need to call at runtime. As those functions live in the std crate,
     // the paths are prefixed with "std::". Unfortunately, these paths can't
@@ -76,16 +81,7 @@ fn mk_ctxt(sess: &session) -> ext_ctxt {
     // super-ugly and needs a better solution.
     let crate_file_name_hack = sess.get_codemap().files.(0).name;
 
-    fn ext_next_id_(sess: &session) -> ast::node_id {
-        ret sess.next_node_id(); // temporary, until bind works better
-    }
-    let ext_next_id = bind ext_next_id_(sess);
-    ret {crate_file_name_hack: crate_file_name_hack,
-         span_fatal: ext_span_fatal,
-         span_unimpl: ext_span_unimpl,
-         span_bug: ext_span_bug,
-         bug: ext_bug,
-         next_id: ext_next_id};
+    ret ext_ctxt(@sess, crate_file_name_hack, ~[]);
 }
 
 fn expr_to_str(cx: &ext_ctxt, expr: @ast::expr, error: str) -> str {
diff --git a/src/comp/syntax/ext/expand.rs b/src/comp/syntax/ext/expand.rs
index e47a0fc2a71..790e892cec2 100644
--- a/src/comp/syntax/ext/expand.rs
+++ b/src/comp/syntax/ext/expand.rs
@@ -1,11 +1,4 @@
-
-import codemap::emit_error;
 import driver::session;
-import syntax::ast::crate;
-import syntax::ast::expr_;
-import syntax::ast::expr_mac;
-import syntax::ast::mac_invoc;
-import syntax::fold::*;
 
 import std::option::none;
 import std::option::some;
@@ -13,40 +6,46 @@ import std::option::some;
 import std::map::hashmap;
 import std::ivec;
 
-fn expand_expr(exts: &hashmap[str, base::syntax_extension],
-               sess: &session::session, e: &expr_, fld: ast_fold,
-               orig: &fn(&ast::expr_, ast_fold) -> expr_ ) -> expr_ {
+import syntax::ast::crate;
+import syntax::ast::expr_;
+import syntax::ast::expr_mac;
+import syntax::ast::mac_invoc;
+import syntax::fold::*;
+import syntax::ext::base::*;
+
+
+fn expand_expr(exts: &hashmap[str, syntax_extension], cx: &ext_ctxt,
+               e: &expr_, fld: ast_fold,
+               orig: &fn(&expr_, ast_fold) -> expr_ ) -> expr_ {
     ret alt e {
           expr_mac(mac) {
             alt mac.node {
               mac_invoc(pth, args, body) {
                 assert (ivec::len(pth.node.idents) > 0u);
                 let extname = pth.node.idents.(0);
-                let ext_cx = base::mk_ctxt(sess);
                 alt exts.find(extname) {
                   none. {
-                    emit_error(some(pth.span),
-                               "unknown syntax expander: '" + extname + "'",
-                               sess.get_codemap());
-                    fail
+                    cx.span_fatal(pth.span,
+                                  #fmt["macro undefined: '%s'", extname])
                   }
-                  some(base::normal(ext)) {
+                  some(normal(ext)) {
+                    let expanded = ext(cx, pth.span, args, body);
 
+                    cx.bt_push(mac.span);
                     //keep going, outside-in
-                    fld.fold_expr(ext(ext_cx, pth.span, args, body)).node
+                    let fully_expanded = fld.fold_expr(expanded).node;
+                    cx.bt_pop();
+
+                    fully_expanded
                   }
-                  some(base::macro_defining(ext)) {
-                    let named_extension = ext(ext_cx, pth.span, args, body);
+                  some(macro_defining(ext)) {
+                    let named_extension = ext(cx, pth.span, args, body);
                     exts.insert(named_extension.ident, named_extension.ext);
                     ast::expr_rec(~[], none)
                   }
                 }
               }
-              _ {
-                emit_error(some(mac.span), "naked syntactic bit",
-                           sess.get_codemap());
-                fail
-              }
+              _ { cx.span_bug(mac.span, "naked syntactic bit") }
             }
           }
           _ { orig(e, fld) }
@@ -54,10 +53,11 @@ fn expand_expr(exts: &hashmap[str, base::syntax_extension],
 }
 
 fn expand_crate(sess: &session::session, c: &@crate) -> @crate {
-    let exts = ext::base::syntax_expander_table();
+    let exts = syntax_expander_table();
     let afp = default_ast_fold();
+    let cx: ext_ctxt = mk_ctxt(sess);
     let f_pre =
-        {fold_expr: bind expand_expr(exts, sess, _, _, afp.fold_expr)
+        {fold_expr: bind expand_expr(exts, cx, _, _, afp.fold_expr)
             with *afp};
     let f = make_fold(f_pre);
     let res = @f.fold_crate(*c);
diff --git a/src/comp/syntax/ext/fmt.rs b/src/comp/syntax/ext/fmt.rs
index 8aa9ce308a7..27fcece7fb5 100644
--- a/src/comp/syntax/ext/fmt.rs
+++ b/src/comp/syntax/ext/fmt.rs
@@ -98,7 +98,7 @@ fn pieces_to_expr(cx: &ext_ctxt, sp: span, pieces: &[piece],
     }
     fn make_path_vec(cx: &ext_ctxt, ident: str) -> [str] {
         fn compiling_std(cx: &ext_ctxt) -> bool {
-            ret str::find(cx.crate_file_name_hack, "std.rc") >= 0;
+            ret str::find(cx.crate_file_name(), "std.rc") >= 0;
         }
         if compiling_std(cx) {
             ret ~["extfmt", "rt", ident];