Add types for character position and byte position in the codemap

20 files changed, 277 insertions, 154 deletions

diff --git a/src/libsyntax/ast_util.rs b/src/libsyntax/ast_util.rs
index d406c98d884..6abcef5c708 100644
--- a/src/libsyntax/ast_util.rs
+++ b/src/libsyntax/ast_util.rs
@@ -1,7 +1,7 @@
-use codemap::span;
+use codemap::{span, CharPos};
 use ast::*;
 
-pure fn spanned<T>(lo: uint, hi: uint, +t: T) -> spanned<T> {
+pure fn spanned<T>(+lo: CharPos, +hi: CharPos, +t: T) -> spanned<T> {
     respan(mk_sp(lo, hi), move t)
 }
 
@@ -14,12 +14,12 @@ pure fn dummy_spanned<T>(+t: T) -> spanned<T> {
 }
 
 /* assuming that we're not in macro expansion */
-pure fn mk_sp(lo: uint, hi: uint) -> span {
+pure fn mk_sp(+lo: CharPos, +hi: CharPos) -> span {
     span {lo: lo, hi: hi, expn_info: None}
 }
 
 // make this a const, once the compiler supports it
-pure fn dummy_sp() -> span { return mk_sp(0u, 0u); }
+pure fn dummy_sp() -> span { return mk_sp(CharPos(0), CharPos(0)); }
 
 
 
diff --git a/src/libsyntax/attr.rs b/src/libsyntax/attr.rs
index 8c19814350c..3b6bae64104 100644
--- a/src/libsyntax/attr.rs
+++ b/src/libsyntax/attr.rs
@@ -6,6 +6,7 @@ use either::Either;
 use diagnostic::span_handler;
 use ast_util::{spanned, dummy_spanned};
 use parse::comments::{doc_comment_style, strip_doc_comment_decoration};
+use codemap::CharPos;
 
 // Constructors
 export mk_name_value_item_str;
@@ -74,7 +75,8 @@ fn mk_attr(item: @ast::meta_item) -> ast::attribute {
                        is_sugared_doc: false});
 }
 
-fn mk_sugared_doc_attr(text: ~str, lo: uint, hi: uint) -> ast::attribute {
+fn mk_sugared_doc_attr(text: ~str,
+                       +lo: CharPos, +hi: CharPos) -> ast::attribute {
     let lit = spanned(lo, hi, ast::lit_str(@text));
     let attr = {
         style: doc_comment_style(text),
diff --git a/src/libsyntax/codemap.rs b/src/libsyntax/codemap.rs
index 87328f25ca8..8333849b21d 100644
--- a/src/libsyntax/codemap.rs
+++ b/src/libsyntax/codemap.rs
@@ -10,8 +10,109 @@ use std::serialization::{Serializable,
                          Serializer,
                          Deserializer};
 
-pub type BytePos = uint;
-pub type CharPos = uint;
+trait Pos {
+    static pure fn from_uint(n: uint) -> self;
+    pure fn to_uint(&self) -> uint;
+}
+
+pub enum BytePos = uint;
+pub enum CharPos = uint;
+
+impl BytePos: Pos {
+    static pure fn from_uint(n: uint) -> BytePos { BytePos(n) }
+    pure fn to_uint(&self) -> uint { **self }
+}
+
+impl BytePos: cmp::Eq {
+    pure fn eq(other: &BytePos) -> bool {
+        *self == **other
+    }
+    pure fn ne(other: &BytePos) -> bool { !self.eq(other) }
+}
+
+impl BytePos: cmp::Ord {
+    pure fn lt(other: &BytePos) -> bool { *self < **other }
+    pure fn le(other: &BytePos) -> bool { *self <= **other }
+    pure fn ge(other: &BytePos) -> bool { *self >= **other }
+    pure fn gt(other: &BytePos) -> bool { *self > **other }
+}
+
+impl BytePos: Num {
+    pure fn add(other: &BytePos) -> BytePos {
+        BytePos(*self + **other)
+    }
+    pure fn sub(other: &BytePos) -> BytePos {
+        BytePos(*self - **other)
+    }
+    pure fn mul(other: &BytePos) -> BytePos {
+        BytePos(*self * (**other))
+    }
+    pure fn div(other: &BytePos) -> BytePos {
+        BytePos(*self / **other)
+    }
+    pure fn modulo(other: &BytePos) -> BytePos {
+        BytePos(*self % **other)
+    }
+    pure fn neg() -> BytePos {
+        BytePos(-*self)
+    }
+    pure fn to_int() -> int { *self as int }
+    static pure fn from_int(+n: int) -> BytePos { BytePos(n as uint) }
+}
+
+impl BytePos: to_bytes::IterBytes {
+    pure fn iter_bytes(+lsb0: bool, f: to_bytes::Cb) {
+        (*self).iter_bytes(lsb0, f)
+    }
+}
+
+impl CharPos: Pos {
+    static pure fn from_uint(n: uint) -> CharPos { CharPos(n) }
+    pure fn to_uint(&self) -> uint { **self }
+}
+
+impl CharPos: cmp::Eq {
+    pure fn eq(other: &CharPos) -> bool {
+        *self == **other
+    }
+    pure fn ne(other: &CharPos) -> bool { !self.eq(other) }
+}
+
+impl CharPos: cmp::Ord {
+    pure fn lt(other: &CharPos) -> bool { *self < **other }
+    pure fn le(other: &CharPos) -> bool { *self <= **other }
+    pure fn ge(other: &CharPos) -> bool { *self >= **other }
+    pure fn gt(other: &CharPos) -> bool { *self > **other }
+}
+
+impl CharPos: Num {
+    pure fn add(other: &CharPos) -> CharPos {
+        CharPos(*self + **other)
+    }
+    pure fn sub(other: &CharPos) -> CharPos {
+        CharPos(*self - **other)
+    }
+    pure fn mul(other: &CharPos) -> CharPos {
+        CharPos(*self * (**other))
+    }
+    pure fn div(other: &CharPos) -> CharPos {
+        CharPos(*self / **other)
+    }
+    pure fn modulo(other: &CharPos) -> CharPos {
+        CharPos(*self % **other)
+    }
+    pure fn neg() -> CharPos {
+        CharPos(-*self)
+    }
+    pure fn to_int() -> int { *self as int }
+    static pure fn from_int(+n: int) -> CharPos { CharPos(n as uint) }
+}
+
+impl CharPos: to_bytes::IterBytes {
+    pure fn iter_bytes(+lsb0: bool, f: to_bytes::Cb) {
+        (*self).iter_bytes(lsb0, f)
+    }
+}
 
 pub struct span {
     lo: CharPos,
@@ -37,8 +138,8 @@ impl<D: Deserializer> span: Deserializable<D> {
     }
 }
 
-pub struct Loc {
-    file: @FileMap, line: uint, col: uint
+pub struct Loc<A: Pos> {
+    file: @FileMap, line: uint, col: A
 }
 
 pub struct FilePos {
@@ -69,7 +170,7 @@ pub struct FileLines {
 pub enum FileSubstr {
     pub FssNone,
     pub FssInternal(span),
-    pub FssExternal({filename: ~str, line: uint, col: uint})
+    pub FssExternal({filename: ~str, line: uint, col: CharPos})
 }
 
 pub struct FileMap {
@@ -83,7 +184,7 @@ pub struct FileMap {
 pub impl FileMap {
     static fn new_w_substr(+filename: FileName, +substr: FileSubstr,
                            src: @~str,
-                           start_pos_ch: uint, start_pos_byte: uint)
+                           +start_pos_ch: CharPos, +start_pos_byte: BytePos)
         -> FileMap {
         return FileMap {
             name: filename, substr: substr, src: src,
@@ -93,18 +194,22 @@ pub impl FileMap {
     }
 
     static fn new(+filename: FileName, src: @~str,
-                  start_pos_ch: CharPos, start_pos_byte: BytePos)
+                  +start_pos_ch: CharPos, +start_pos_byte: BytePos)
         -> FileMap {
         return FileMap::new_w_substr(filename, FssNone, src,
                                      start_pos_ch, start_pos_byte);
     }
 
-    fn next_line(@self, chpos: CharPos, byte_pos: BytePos) {
-        self.lines.push(FilePos {ch: chpos, byte: byte_pos + self.start_pos.byte});
+    fn next_line(@self, +chpos: CharPos, +byte_pos: BytePos) {
+        self.lines.push(FilePos {
+            ch: chpos,
+            byte: byte_pos + self.start_pos.byte
+        });
     }
 
     pub fn get_line(@self, line: int) -> ~str unsafe {
-        let begin: uint = self.lines[line].byte - self.start_pos.byte;
+        let begin: BytePos = self.lines[line].byte - self.start_pos.byte;
+        let begin = begin.to_uint();
         let end = match str::find_char_from(*self.src, '\n', begin) {
             Some(e) => e,
             None => str::len(*self.src)
@@ -127,21 +232,22 @@ pub impl CodeMap {
 
     pub fn mk_substr_filename(@self, sp: span) -> ~str {
         let pos = self.lookup_char_pos(sp.lo);
-        return fmt!("<%s:%u:%u>", pos.file.name, pos.line, pos.col);
+        return fmt!("<%s:%u:%u>", pos.file.name,
+                    pos.line, pos.col.to_uint());
     }
 
-    pub fn lookup_char_pos(@self, pos: CharPos) -> Loc {
-        pure fn lookup(pos: FilePos) -> uint { return pos.ch; }
+    pub fn lookup_char_pos(@self, +pos: CharPos) -> Loc<CharPos> {
+        pure fn lookup(pos: FilePos) -> uint { return pos.ch.to_uint(); }
         return self.lookup_pos(pos, lookup);
     }
 
-    pub fn lookup_byte_pos(@self, pos: BytePos) -> Loc {
-        pure fn lookup(pos: FilePos) -> uint { return pos.byte; }
+    pub fn lookup_byte_pos(@self, +pos: BytePos) -> Loc<BytePos> {
+        pure fn lookup(pos: FilePos) -> uint { return pos.byte.to_uint(); }
         return self.lookup_pos(pos, lookup);
     }
 
-    pub fn lookup_char_pos_adj(@self, pos: CharPos)
-        -> {filename: ~str, line: uint, col: uint, file: Option<@FileMap>}
+    pub fn lookup_char_pos_adj(@self, +pos: CharPos)
+        -> {filename: ~str, line: uint, col: CharPos, file: Option<@FileMap>}
     {
         let loc = self.lookup_char_pos(pos);
         match (loc.file.substr) {
@@ -152,7 +258,8 @@ pub impl CodeMap {
                  file: Some(loc.file)}
             }
             FssInternal(sp) => {
-                self.lookup_char_pos_adj(sp.lo + (pos - loc.file.start_pos.ch))
+                self.lookup_char_pos_adj(
+                    sp.lo + (pos - loc.file.start_pos.ch))
             }
             FssExternal(eloc) => {
                 {filename: /* FIXME (#2543) */ copy eloc.filename,
@@ -164,14 +271,17 @@ pub impl CodeMap {
     }
 
     pub fn adjust_span(@self, sp: span) -> span {
-        pure fn lookup(pos: FilePos) -> uint { return pos.ch; }
+        pure fn lookup(pos: FilePos) -> uint { return pos.ch.to_uint(); }
         let line = self.lookup_line(sp.lo, lookup);
         match (line.fm.substr) {
             FssNone => sp,
             FssInternal(s) => {
-                self.adjust_span(span {lo: s.lo + (sp.lo - line.fm.start_pos.ch),
-                                       hi: s.lo + (sp.hi - line.fm.start_pos.ch),
-                                       expn_info: sp.expn_info})}
+                self.adjust_span(span {
+                    lo: s.lo + (sp.lo - line.fm.start_pos.ch),
+                    hi: s.lo + (sp.hi - line.fm.start_pos.ch),
+                    expn_info: sp.expn_info
+                })
+            }
             FssExternal(_) => sp
         }
     }
@@ -180,7 +290,7 @@ pub impl CodeMap {
         let lo = self.lookup_char_pos_adj(sp.lo);
         let hi = self.lookup_char_pos_adj(sp.hi);
         return fmt!("%s:%u:%u: %u:%u", lo.filename,
-                    lo.line, lo.col, hi.line, hi.col)
+                    lo.line, lo.col.to_uint(), hi.line, hi.col.to_uint())
     }
 
     pub fn span_to_filename(@self, sp: span) -> FileName {
@@ -198,21 +308,24 @@ pub impl CodeMap {
         return @FileLines {file: lo.file, lines: lines};
     }
 
-    fn lookup_byte_offset(@self, chpos: CharPos)
+    fn lookup_byte_offset(@self, +chpos: CharPos)
         -> {fm: @FileMap, pos: BytePos} {
-        pure fn lookup(pos: FilePos) -> uint { return pos.ch; }
+        pure fn lookup(pos: FilePos) -> uint { return pos.ch.to_uint(); }
         let {fm, line} = self.lookup_line(chpos, lookup);
         let line_offset = fm.lines[line].byte - fm.start_pos.byte;
         let col = chpos - fm.lines[line].ch;
-        let col_offset = str::count_bytes(*fm.src, line_offset, col);
-        {fm: fm, pos: line_offset + col_offset}
+        let col_offset = str::count_bytes(*fm.src,
+                                          line_offset.to_uint(),
+                                          col.to_uint());
+        {fm: fm, pos: line_offset + BytePos(col_offset)}
     }
 
     pub fn span_to_snippet(@self, sp: span) -> ~str {
         let begin = self.lookup_byte_offset(sp.lo);
         let end = self.lookup_byte_offset(sp.hi);
         assert begin.fm.start_pos == end.fm.start_pos;
-        return str::slice(*begin.fm.src, begin.pos, end.pos);
+        return str::slice(*begin.fm.src,
+                          begin.pos.to_uint(), end.pos.to_uint());
     }
 
     pub fn get_filemap(@self, filename: ~str) -> @FileMap {
@@ -225,7 +338,7 @@ pub impl CodeMap {
 }
 
 priv impl CodeMap {
-    fn lookup_line(@self, pos: uint, lookup: LookupFn)
+    fn lookup_line<A: Pos>(@self, pos: A, lookup: LookupFn)
         -> {fm: @FileMap, line: uint}
     {
         let len = self.files.len();
@@ -233,31 +346,40 @@ priv impl CodeMap {
         let mut b = len;
         while b - a > 1u {
             let m = (a + b) / 2u;
-            if lookup(self.files[m].start_pos) > pos { b = m; } else { a = m; }
+            if lookup(self.files[m].start_pos) > pos.to_uint() {
+                b = m;
+            } else {
+                a = m;
+            }
         }
         if (a >= len) {
-            fail fmt!("position %u does not resolve to a source location", pos)
+            fail fmt!("position %u does not resolve to a source location",
+                      pos.to_uint())
         }
         let f = self.files[a];
         a = 0u;
         b = vec::len(f.lines);
         while b - a > 1u {
             let m = (a + b) / 2u;
-            if lookup(f.lines[m]) > pos { b = m; } else { a = m; }
+            if lookup(f.lines[m]) > pos.to_uint() { b = m; } else { a = m; }
         }
         return {fm: f, line: a};
     }
 
-    fn lookup_pos(@self, pos: uint, lookup: LookupFn) -> Loc {
+    fn lookup_pos<A: Pos Num>(@self, pos: A, lookup: LookupFn) -> Loc<A> {
         let {fm: f, line: a} = self.lookup_line(pos, lookup);
-        return Loc {file: f, line: a + 1u, col: pos - lookup(f.lines[a])};
+        return Loc {
+            file: f,
+            line: a + 1u,
+            col: pos - from_uint(lookup(f.lines[a]))
+        };
     }
 
     fn span_to_str_no_adj(@self, sp: span) -> ~str {
         let lo = self.lookup_char_pos(sp.lo);
         let hi = self.lookup_char_pos(sp.hi);
         return fmt!("%s:%u:%u: %u:%u", lo.file.name,
-                    lo.line, lo.col, hi.line, hi.col)
+                    lo.line, lo.col.to_uint(), hi.line, hi.col.to_uint())
     }
 }
 
diff --git a/src/libsyntax/diagnostic.rs b/src/libsyntax/diagnostic.rs
index 22bed009c9a..007100856eb 100644
--- a/src/libsyntax/diagnostic.rs
+++ b/src/libsyntax/diagnostic.rs
@@ -245,7 +245,7 @@ fn highlight_lines(cm: @codemap::CodeMap, sp: span,
         while num > 0u { num /= 10u; digits += 1u; }
 
         // indent past |name:## | and the 0-offset column location
-        let mut left = str::len(fm.name) + digits + lo.col + 3u;
+        let mut left = str::len(fm.name) + digits + lo.col.to_uint() + 3u;
         let mut s = ~"";
         while left > 0u { str::push_char(&mut s, ' '); left -= 1u; }
 
@@ -253,7 +253,7 @@ fn highlight_lines(cm: @codemap::CodeMap, sp: span,
         let hi = cm.lookup_char_pos(sp.hi);
         if hi.col != lo.col {
             // the ^ already takes up one space
-            let mut width = hi.col - lo.col - 1u;
+            let mut width = hi.col.to_uint() - lo.col.to_uint() - 1u;
             while width > 0u { str::push_char(&mut s, '~'); width -= 1u; }
         }
         io::stderr().write_str(s + ~"\n");
diff --git a/src/libsyntax/ext/base.rs b/src/libsyntax/ext/base.rs
index ad33e99ff04..66ef3bec2a7 100644
--- a/src/libsyntax/ext/base.rs
+++ b/src/libsyntax/ext/base.rs
@@ -178,7 +178,9 @@ fn mk_ctxt(parse_sess: parse::parse_sess,
         }
         fn bt_pop() {
             match self.backtrace {
-              Some(@ExpandedFrom({call_site: span {expn_info: prev, _}, _})) => {
+              Some(@ExpandedFrom({
+                  call_site: span {expn_info: prev, _}, _
+              })) => {
                 self.backtrace = prev
               }
               _ => self.bug(~"tried to pop without a push")
diff --git a/src/libsyntax/ext/pipes/ast_builder.rs b/src/libsyntax/ext/pipes/ast_builder.rs
index 3d63b0ddb77..652ad5533c4 100644
--- a/src/libsyntax/ext/pipes/ast_builder.rs
+++ b/src/libsyntax/ext/pipes/ast_builder.rs
@@ -4,7 +4,7 @@
 // something smarter.
 
 use ast::{ident, node_id};
-use ast_util::{ident_to_path, respan};
+use ast_util::{ident_to_path, respan, dummy_sp};
 use codemap::span;
 use ext::base::mk_ctxt;
 
@@ -23,10 +23,6 @@ fn path(ids: ~[ident], span: span) -> @ast::path {
       types: ~[]}
 }
 
-fn empty_span() -> span {
-    span {lo: 0, hi: 0, expn_info: None}
-}
-
 trait append_types {
     fn add_ty(ty: @ast::Ty) -> @ast::path;
     fn add_tys(+tys: ~[@ast::Ty]) -> @ast::path;
@@ -83,26 +79,21 @@ trait ext_ctxt_ast_builder {
     fn stmt_let(ident: ident, e: @ast::expr) -> @ast::stmt;
     fn stmt_expr(e: @ast::expr) -> @ast::stmt;
     fn block_expr(b: ast::blk) -> @ast::expr;
-    fn empty_span() -> span;
     fn ty_option(ty: @ast::Ty) -> @ast::Ty;
 }
 
 impl ext_ctxt: ext_ctxt_ast_builder {
     fn ty_option(ty: @ast::Ty) -> @ast::Ty {
         self.ty_path_ast_builder(path(~[self.ident_of(~"Option")],
-                                      self.empty_span())
+                                      dummy_sp())
                                  .add_ty(ty))
     }
 
-    fn empty_span() -> span {
-        span {lo: 0, hi: 0, expn_info: self.backtrace()}
-    }
-
     fn block_expr(b: ast::blk) -> @ast::expr {
         @{id: self.next_id(),
           callee_id: self.next_id(),
           node: ast::expr_block(b),
-          span: self.empty_span()}
+          span: dummy_sp()}
     }
 
     fn move_expr(e: @ast::expr) -> @ast::expr {
@@ -114,7 +105,7 @@ impl ext_ctxt: ext_ctxt_ast_builder {
 
     fn stmt_expr(e: @ast::expr) -> @ast::stmt {
         @{node: ast::stmt_expr(e, self.next_id()),
-          span: self.empty_span()}
+          span: dummy_sp()}
     }
 
     fn stmt_let(ident: ident, e: @ast::expr) -> @ast::stmt {
@@ -130,43 +121,43 @@ impl ext_ctxt: ext_ctxt_ast_builder {
                      pat: @{id: self.next_id(),
                             node: ast::pat_ident(ast::bind_by_implicit_ref,
                                                  path(~[ident],
-                                                      self.empty_span()),
+                                                      dummy_sp()),
                                                  None),
-                            span: self.empty_span()},
+                            span: dummy_sp()},
                      init: Some(self.move_expr(e)),
                      id: self.next_id()},
-              span: self.empty_span()}]),
-                               span: self.empty_span()}, self.next_id()),
-         span: self.empty_span()}
+              span: dummy_sp()}]),
+                               span: dummy_sp()}, self.next_id()),
+         span: dummy_sp()}
     }
 
     fn field_imm(name: ident, e: @ast::expr) -> ast::field {
         {node: {mutbl: ast::m_imm, ident: name, expr: e},
-         span: self.empty_span()}
+         span: dummy_sp()}
     }
 
     fn rec(+fields: ~[ast::field]) -> @ast::expr {
         @{id: self.next_id(),
           callee_id: self.next_id(),
           node: ast::expr_rec(fields, None),
-          span: self.empty_span()}
+          span: dummy_sp()}
     }
 
     fn ty_field_imm(name: ident, ty: @ast::Ty) -> ast::ty_field {
         {node: {ident: name, mt: { ty: ty, mutbl: ast::m_imm } },
-          span: self.empty_span()}
+          span: dummy_sp()}
     }
 
     fn ty_rec(+fields: ~[ast::ty_field]) -> @ast::Ty {
         @{id: self.next_id(),
           node: ast::ty_rec(fields),
-          span: self.empty_span()}
+          span: dummy_sp()}
     }
 
     fn ty_infer() -> @ast::Ty {
         @{id: self.next_id(),
           node: ast::ty_infer,
-          span: self.empty_span()}
+          span: dummy_sp()}
     }
 
     fn ty_param(id: ast::ident, +bounds: ~[ast::ty_param_bound])
@@ -181,9 +172,9 @@ impl ext_ctxt: ext_ctxt_ast_builder {
          pat: @{id: self.next_id(),
                 node: ast::pat_ident(
                     ast::bind_by_value,
-                    ast_util::ident_to_path(self.empty_span(), name),
+                    ast_util::ident_to_path(dummy_sp(), name),
                     None),
-                span: self.empty_span()},
+                span: dummy_sp()},
          id: self.next_id()}
     }
 
@@ -195,7 +186,7 @@ impl ext_ctxt: ext_ctxt_ast_builder {
                    rules: ast::default_blk};
 
         {node: blk,
-         span: self.empty_span()}
+         span: dummy_sp()}
     }
 
     fn expr_block(e: @ast::expr) -> ast::blk {
@@ -215,11 +206,11 @@ impl ext_ctxt: ext_ctxt_ast_builder {
 
         // XXX: Would be nice if our generated code didn't violate
         // Rust coding conventions
-        let non_camel_case_attribute = respan(self.empty_span(), {
+        let non_camel_case_attribute = respan(dummy_sp(), {
             style: ast::attr_outer,
-            value: respan(self.empty_span(),
+            value: respan(dummy_sp(),
                           ast::meta_list(~"allow", ~[
-                              @respan(self.empty_span(),
+                              @respan(dummy_sp(),
                                       ast::meta_word(~"non_camel_case_types"))
                           ])),
             is_sugared_doc: false
@@ -239,7 +230,7 @@ impl ext_ctxt: ext_ctxt_ast_builder {
                     +ty_params: ~[ast::ty_param],
                     +body: ast::blk) -> @ast::item {
         self.item(name,
-                  self.empty_span(),
+                  dummy_sp(),
                   ast::item_fn(self.fn_decl(inputs, output),
                                ast::impure_fn,
                                ty_params,
@@ -298,7 +289,7 @@ impl ext_ctxt: ext_ctxt_ast_builder {
     fn ty_nil_ast_builder() -> @ast::Ty {
         @{id: self.next_id(),
           node: ast::ty_nil,
-          span: self.empty_span()}
+          span: dummy_sp()}
     }
 
     fn item_ty_poly(name: ident,
@@ -314,6 +305,6 @@ impl ext_ctxt: ext_ctxt_ast_builder {
 
     fn ty_vars(+ty_params: ~[ast::ty_param]) -> ~[@ast::Ty] {
         ty_params.map(|p| self.ty_path_ast_builder(
-            path(~[p.ident], self.empty_span())))
+            path(~[p.ident], dummy_sp())))
     }
 }
diff --git a/src/libsyntax/ext/pipes/check.rs b/src/libsyntax/ext/pipes/check.rs
index fcc0c84a4ff..a90b679f697 100644
--- a/src/libsyntax/ext/pipes/check.rs
+++ b/src/libsyntax/ext/pipes/check.rs
@@ -22,7 +22,6 @@ that.
 use ext::base::ext_ctxt;
 
 use proto::{state, protocol, next_state};
-use ast_builder::empty_span;
 
 impl ext_ctxt: proto::visitor<(), (), ()>  {
     fn visit_proto(_proto: protocol,
diff --git a/src/libsyntax/ext/pipes/liveness.rs b/src/libsyntax/ext/pipes/liveness.rs
index a9bfd87ab0e..e86b3f0ea59 100644
--- a/src/libsyntax/ext/pipes/liveness.rs
+++ b/src/libsyntax/ext/pipes/liveness.rs
@@ -29,8 +29,6 @@ updating the states using rule (2) until there are no changes.
 
 use std::bitv::{Bitv};
 
-use ast_builder::empty_span;
-
 fn analyze(proto: protocol, _cx: ext_ctxt) {
     debug!("initializing colive analysis");
     let num_states = proto.num_states();
diff --git a/src/libsyntax/ext/pipes/pipec.rs b/src/libsyntax/ext/pipes/pipec.rs
index 7e1cbe9ad0d..d03a0fde66c 100644
--- a/src/libsyntax/ext/pipes/pipec.rs
+++ b/src/libsyntax/ext/pipes/pipec.rs
@@ -5,6 +5,7 @@ use to_str::ToStr;
 use dvec::DVec;
 
 use ast::ident;
+use ast_util::dummy_sp;
 use util::interner;
 use print::pprust;
 use pprust::{item_to_str, ty_to_str};
@@ -12,7 +13,7 @@ use ext::base::{mk_ctxt, ext_ctxt};
 use parse::*;
 use proto::*;
 
-use ast_builder::{append_types, path, empty_span};
+use ast_builder::{append_types, path};
 
 // Transitional reexports so qquote can find the paths it is looking for
 mod syntax {
@@ -256,11 +257,11 @@ impl state: to_type_decls {
                     cx.ty_path_ast_builder(
                         path(~[cx.ident_of(~"pipes"),
                                cx.ident_of(dir.to_str() + ~"Packet")],
-                             empty_span())
+                             dummy_sp())
                         .add_ty(cx.ty_path_ast_builder(
                             path(~[cx.ident_of(self.proto.name),
                                    self.data_name()],
-                                 empty_span())
+                                 dummy_sp())
                             .add_tys(cx.ty_vars(self.ty_params))))),
                     self.ty_params));
         }
@@ -273,11 +274,11 @@ impl state: to_type_decls {
                         path(~[cx.ident_of(~"pipes"),
                                cx.ident_of(dir.to_str()
                                            + ~"PacketBuffered")],
-                             empty_span())
+                             dummy_sp())
                         .add_tys(~[cx.ty_path_ast_builder(
                             path(~[cx.ident_of(self.proto.name),
                                    self.data_name()],
-                                 empty_span())
+                                 dummy_sp())
                             .add_tys(cx.ty_vars(self.ty_params))),
                                    self.proto.buffer_ty_path(cx)])),
                     self.ty_params));
@@ -394,7 +395,7 @@ impl protocol: gen_init {
 
         cx.item_ty_poly(
             cx.ident_of(~"__Buffer"),
-            cx.empty_span(),
+            dummy_sp(),
             cx.ty_rec(fields),
             params)
     }
diff --git a/src/libsyntax/ext/qquote.rs b/src/libsyntax/ext/qquote.rs
index 1d17b09329c..50d1e0033e2 100644
--- a/src/libsyntax/ext/qquote.rs
+++ b/src/libsyntax/ext/qquote.rs
@@ -4,6 +4,7 @@ use parse::parser;
 use parse::parser::{Parser, parse_from_source_str};
 use dvec::DVec;
 use parse::token::ident_interner;
+use codemap::CharPos;
 
 use fold::*;
 use visit::*;
@@ -15,13 +16,13 @@ use io::*;
 use codemap::span;
 
 struct gather_item {
-    lo: uint,
-    hi: uint,
+    lo: CharPos,
+    hi: CharPos,
     e: @ast::expr,
     constr: ~str
 }
 
-type aq_ctxt = @{lo: uint, gather: DVec<gather_item>};
+type aq_ctxt = @{lo: CharPos, gather: DVec<gather_item>};
 enum fragment {
     from_expr(@ast::expr),
     from_ty(@ast::Ty)
@@ -114,7 +115,7 @@ impl @ast::pat: qq_helper {
     fn get_fold_fn() -> ~str {~"fold_pat"}
 }
 
-fn gather_anti_quotes<N: qq_helper>(lo: uint, node: N) -> aq_ctxt
+fn gather_anti_quotes<N: qq_helper>(lo: CharPos, node: N) -> aq_ctxt
 {
     let v = @{visit_expr: |node, &&cx, v| visit_aq(node, ~"from_expr", cx, v),
               visit_ty: |node, &&cx, v| visit_aq(node, ~"from_ty", cx, v),
@@ -226,7 +227,8 @@ fn finish<T: qq_helper>
     let mut str2 = ~"";
     enum state {active, skip(uint), blank};
     let mut state = active;
-    let mut i = 0u, j = 0u;
+    let mut i = CharPos(0u);
+    let mut j = 0u;
     let g_len = cx.gather.len();
     for str::chars_each(*str) |ch| {
         if (j < g_len && i == cx.gather[j].lo) {
@@ -242,7 +244,7 @@ fn finish<T: qq_helper>
           blank if is_space(ch) => str::push_char(&mut str2, ch),
           blank => str::push_char(&mut str2, ' ')
         }
-        i += 1u;
+        i += CharPos(1u);
         if (j < g_len && i == cx.gather[j].hi) {
             assert ch == ')';
             state = active;
@@ -270,7 +272,7 @@ fn finish<T: qq_helper>
                                  ~"qquote", ~"mk_file_substr"]),
                                 ~[mk_uniq_str(cx,sp, loc.file.name),
                                  mk_uint(cx,sp, loc.line),
-                                 mk_uint(cx,sp, loc.col)]),
+                                 mk_uint(cx,sp, loc.col.to_uint())]),
                         mk_unary(cx,sp, ast::box(ast::m_imm),
                                  mk_uniq_str(cx,sp, str2)),
                         cfg_call(),
@@ -346,7 +348,7 @@ fn replace_ty(repls: ~[fragment],
 
 fn mk_file_substr(fname: ~str, line: uint, col: uint) ->
     codemap::FileSubstr {
-    codemap::FssExternal({filename: fname, line: line, col: col})
+    codemap::FssExternal({filename: fname, line: line, col: CharPos(col)})
 }
 
 // Local Variables:
diff --git a/src/libsyntax/ext/source_util.rs b/src/libsyntax/ext/source_util.rs
index 3e4f24dff02..3fed340904a 100644
--- a/src/libsyntax/ext/source_util.rs
+++ b/src/libsyntax/ext/source_util.rs
@@ -25,7 +25,7 @@ fn expand_col(cx: ext_ctxt, sp: span, arg: ast::mac_arg,
               _body: ast::mac_body) -> @ast::expr {
     get_mac_args(cx, sp, arg, 0u, option::Some(0u), ~"col");
     let loc = cx.codemap().lookup_char_pos(sp.lo);
-    return mk_uint(cx, sp, loc.col);
+    return mk_uint(cx, sp, loc.col.to_uint());
 }
 
 /* file!(): expands to the current filename */
diff --git a/src/libsyntax/ext/tt/macro_parser.rs b/src/libsyntax/ext/tt/macro_parser.rs
index 76814a688f5..2f371e1f8c5 100644
--- a/src/libsyntax/ext/tt/macro_parser.rs
+++ b/src/libsyntax/ext/tt/macro_parser.rs
@@ -11,6 +11,7 @@ use dvec::DVec;
 use ast::{matcher, match_tok, match_seq, match_nonterminal, ident};
 use ast_util::mk_sp;
 use std::map::HashMap;
+use codemap::CharPos;
 
 /* This is an Earley-like parser, without support for in-grammar nonterminals,
 only by calling out to the main rust parser for named nonterminals (which it
@@ -102,7 +103,7 @@ type matcher_pos = ~{
     mut up: matcher_pos_up, // mutable for swapping only
     matches: ~[DVec<@named_match>],
     match_lo: uint, match_hi: uint,
-    sp_lo: uint,
+    sp_lo: CharPos,
 };
 
 fn copy_up(&& mpu: matcher_pos_up) -> matcher_pos {
@@ -122,7 +123,7 @@ fn count_names(ms: &[matcher]) -> uint {
 }
 
 #[allow(non_implicitly_copyable_typarams)]
-fn initial_matcher_pos(ms: ~[matcher], sep: Option<Token>, lo: uint)
+fn initial_matcher_pos(ms: ~[matcher], sep: Option<Token>, lo: CharPos)
     -> matcher_pos {
     let mut match_idx_hi = 0u;
     for ms.each() |elt| {
diff --git a/src/libsyntax/ext/tt/transcribe.rs b/src/libsyntax/ext/tt/transcribe.rs
index 238f9db6ac5..78f0e4fc8f8 100644
--- a/src/libsyntax/ext/tt/transcribe.rs
+++ b/src/libsyntax/ext/tt/transcribe.rs
@@ -53,7 +53,7 @@ fn new_tt_reader(sp_diag: span_handler, itr: @ident_interner,
               mut repeat_len: ~[],
               /* dummy values, never read: */
               mut cur_tok: EOF,
-              mut cur_span: ast_util::mk_sp(0u,0u)
+              mut cur_span: ast_util::dummy_sp()
              };
     tt_next_token(r); /* get cur_tok and cur_span set up */
     return r;
diff --git a/src/libsyntax/parse.rs b/src/libsyntax/parse.rs
index 01461a85220..27338b86bea 100644
--- a/src/libsyntax/parse.rs
+++ b/src/libsyntax/parse.rs
@@ -20,7 +20,7 @@ use util::interner;
 use diagnostic::{span_handler, mk_span_handler, mk_handler, emitter};
 use lexer::{reader, string_reader};
 use parse::token::{ident_interner, mk_ident_interner};
-use codemap::{CodeMap, FileMap};
+use codemap::{CodeMap, FileMap, CharPos, BytePos};
 
 type parse_sess = @{
     cm: @codemap::CodeMap,
@@ -28,8 +28,8 @@ type parse_sess = @{
     span_diagnostic: span_handler,
     interner: @ident_interner,
     // these two must be kept up to date
-    mut chpos: uint,
-    mut byte_pos: uint
+    mut chpos: CharPos,
+    mut byte_pos: BytePos
 };
 
 fn new_parse_sess(demitter: Option<emitter>) -> parse_sess {
@@ -38,7 +38,7 @@ fn new_parse_sess(demitter: Option<emitter>) -> parse_sess {
              mut next_id: 1,
              span_diagnostic: mk_span_handler(mk_handler(demitter), cm),
              interner: mk_ident_interner(),
-             mut chpos: 0u, mut byte_pos: 0u};
+             mut chpos: CharPos(0u), mut byte_pos: BytePos(0u)};
 }
 
 fn new_parse_sess_special_handler(sh: span_handler, cm: @codemap::CodeMap)
@@ -47,7 +47,7 @@ fn new_parse_sess_special_handler(sh: span_handler, cm: @codemap::CodeMap)
              mut next_id: 1,
              span_diagnostic: sh,
              interner: mk_ident_interner(),
-             mut chpos: 0u, mut byte_pos: 0u};
+             mut chpos: CharPos(0u), mut byte_pos: BytePos(0u)};
 }
 
 fn parse_crate_from_file(input: &Path, cfg: ast::crate_cfg,
diff --git a/src/libsyntax/parse/attr.rs b/src/libsyntax/parse/attr.rs
index 42101a431d6..31528c10fe1 100644
--- a/src/libsyntax/parse/attr.rs
+++ b/src/libsyntax/parse/attr.rs
@@ -14,7 +14,7 @@ trait parser_attr {
         -> attr_or_ext;
     fn parse_outer_attributes() -> ~[ast::attribute];
     fn parse_attribute(style: ast::attr_style) -> ast::attribute;
-    fn parse_attribute_naked(style: ast::attr_style, lo: uint) ->
+    fn parse_attribute_naked(style: ast::attr_style, lo: CharPos) ->
         ast::attribute;
     fn parse_inner_attrs_and_next() ->
         {inner: ~[ast::attribute], next: ~[ast::attribute]};
@@ -85,7 +85,7 @@ impl Parser: parser_attr {
         return self.parse_attribute_naked(style, lo);
     }
 
-    fn parse_attribute_naked(style: ast::attr_style, lo: uint) ->
+    fn parse_attribute_naked(style: ast::attr_style, lo: CharPos) ->
         ast::attribute {
         self.expect(token::LBRACKET);
         let meta_item = self.parse_meta_item();
diff --git a/src/libsyntax/parse/comments.rs b/src/libsyntax/parse/comments.rs
index a2f73fd189c..06b042a468a 100644
--- a/src/libsyntax/parse/comments.rs
+++ b/src/libsyntax/parse/comments.rs
@@ -3,7 +3,7 @@ use io::ReaderUtil;
 use util::interner;
 use lexer::{string_reader, bump, is_eof, nextch,
                is_whitespace, get_str_from, reader};
-use codemap::FileMap;
+use codemap::{FileMap, CharPos};
 
 export cmnt;
 export lit;
@@ -28,7 +28,7 @@ impl cmnt_style : cmp::Eq {
     }
 }
 
-type cmnt = {style: cmnt_style, lines: ~[~str], pos: uint};
+type cmnt = {style: cmnt_style, lines: ~[~str], pos: CharPos};
 
 fn is_doc_comment(s: ~str) -> bool {
     s.starts_with(~"///") ||
@@ -137,7 +137,7 @@ fn push_blank_line_comment(rdr: string_reader, comments: &mut ~[cmnt]) {
 fn consume_whitespace_counting_blank_lines(rdr: string_reader,
                                            comments: &mut ~[cmnt]) {
     while is_whitespace(rdr.curr) && !is_eof(rdr) {
-        if rdr.col == 0u && rdr.curr == '\n' {
+        if rdr.col == CharPos(0u) && rdr.curr == '\n' {
             push_blank_line_comment(rdr, comments);
         }
         bump(rdr);
@@ -181,6 +181,8 @@ fn read_line_comments(rdr: string_reader, code_to_the_left: bool,
     }
 }
 
+// FIXME #3961: This is not the right way to convert string byte
+// offsets to characters.
 fn all_whitespace(s: ~str, begin: uint, end: uint) -> bool {
     let mut i: uint = begin;
     while i != end {
@@ -190,9 +192,11 @@ fn all_whitespace(s: ~str, begin: uint, end: uint) -> bool {
 }
 
 fn trim_whitespace_prefix_and_push_line(lines: &mut ~[~str],
-                                        s: ~str, col: uint) {
+                                        s: ~str, col: CharPos) {
     let mut s1;
     let len = str::len(s);
+    // FIXME #3961: Doing bytewise comparison and slicing with CharPos
+    let col = col.to_uint();
     if all_whitespace(s, 0u, uint::min(len, col)) {
         if col < len {
             s1 = str::slice(s, col, len);
@@ -207,7 +211,7 @@ fn read_block_comment(rdr: string_reader, code_to_the_left: bool,
     debug!(">>> block comment");
     let p = rdr.chpos;
     let mut lines: ~[~str] = ~[];
-    let mut col: uint = rdr.col;
+    let mut col: CharPos = rdr.col;
     bump(rdr);
     bump(rdr);
 
@@ -280,7 +284,7 @@ fn consume_comment(rdr: string_reader, code_to_the_left: bool,
     debug!("<<< consume comment");
 }
 
-type lit = {lit: ~str, pos: uint};
+type lit = {lit: ~str, pos: CharPos};
 
 fn gather_comments_and_literals(span_diagnostic: diagnostic::span_handler,
                                 path: ~str,
@@ -289,7 +293,8 @@ fn gather_comments_and_literals(span_diagnostic: diagnostic::span_handler,
     let src = @str::from_bytes(srdr.read_whole_stream());
     let itr = parse::token::mk_fake_ident_interner();
     let rdr = lexer::new_low_level_string_reader
-        (span_diagnostic, @FileMap::new(path, src, 0u, 0u), itr);
+        (span_diagnostic, @FileMap::new(path, src,
+                                        CharPos(0u), BytePos(0u)), itr);
 
     let mut comments: ~[cmnt] = ~[];
     let mut literals: ~[lit] = ~[];
diff --git a/src/libsyntax/parse/common.rs b/src/libsyntax/parse/common.rs
index 50c22c08f4f..66930009eb8 100644
--- a/src/libsyntax/parse/common.rs
+++ b/src/libsyntax/parse/common.rs
@@ -205,7 +205,7 @@ impl Parser: parser_common {
         if self.token == token::GT {
             self.bump();
         } else if self.token == token::BINOP(token::SHR) {
-            self.swap(token::GT, self.span.lo + 1u, self.span.hi);
+            self.swap(token::GT, self.span.lo + CharPos(1u), self.span.hi);
         } else {
             let mut s: ~str = ~"expected `";
             s += token_to_str(self.reader, token::GT);
diff --git a/src/libsyntax/parse/lexer.rs b/src/libsyntax/parse/lexer.rs
index 06b8b1e8eee..dbeaff28625 100644
--- a/src/libsyntax/parse/lexer.rs
+++ b/src/libsyntax/parse/lexer.rs
@@ -1,5 +1,5 @@
 use diagnostic::span_handler;
-use codemap::{span, CodeMap};
+use codemap::{span, CodeMap, CharPos, BytePos};
 use ext::tt::transcribe::{tt_reader,  new_tt_reader, dup_tt_reader,
                              tt_next_token};
 
@@ -21,10 +21,10 @@ trait reader {
 type string_reader = @{
     span_diagnostic: span_handler,
     src: @~str,
-    mut col: uint,
-    mut pos: uint,
+    mut col: CharPos,
+    mut pos: BytePos,
     mut curr: char,
-    mut chpos: uint,
+    mut chpos: CharPos,
     filemap: @codemap::FileMap,
     interner: @token::ident_interner,
     /* cached: */
@@ -46,15 +46,15 @@ fn new_low_level_string_reader(span_diagnostic: span_handler,
                                itr: @token::ident_interner)
     -> string_reader {
     let r = @{span_diagnostic: span_diagnostic, src: filemap.src,
-              mut col: 0u, mut pos: 0u, mut curr: -1 as char,
+              mut col: CharPos(0), mut pos: BytePos(0), mut curr: -1 as char,
               mut chpos: filemap.start_pos.ch,
               filemap: filemap, interner: itr,
               /* dummy values; not read */
               mut peek_tok: token::EOF,
-              mut peek_span: ast_util::mk_sp(0u,0u)};
-    if r.pos < (*filemap.src).len() {
-        let next = str::char_range_at(*r.src, r.pos);
-        r.pos = next.next;
+              mut peek_span: ast_util::dummy_sp()};
+    if r.pos.to_uint() < (*filemap.src).len() {
+        let next = str::char_range_at(*r.src, r.pos.to_uint());
+        r.pos = BytePos(next.next);
         r.curr = next.ch;
     }
     return r;
@@ -124,27 +124,27 @@ fn string_advance_token(&&r: string_reader) {
 
 }
 
-fn get_str_from(rdr: string_reader, start: uint) -> ~str unsafe {
+fn get_str_from(rdr: string_reader, start: BytePos) -> ~str unsafe {
     // I'm pretty skeptical about this subtraction. What if there's a
     // multi-byte character before the mark?
-    return str::slice(*rdr.src, start - 1u, rdr.pos - 1u);
+    return str::slice(*rdr.src, start.to_uint() - 1u, rdr.pos.to_uint() - 1u);
 }
 
 fn bump(rdr: string_reader) {
-    if rdr.pos < (*rdr.src).len() {
-        rdr.col += 1u;
-        rdr.chpos += 1u;
+    if rdr.pos.to_uint() < (*rdr.src).len() {
+        rdr.col += CharPos(1u);
+        rdr.chpos += CharPos(1u);
         if rdr.curr == '\n' {
             rdr.filemap.next_line(rdr.chpos, rdr.pos);
-            rdr.col = 0u;
+            rdr.col = CharPos(0u);
         }
-        let next = str::char_range_at(*rdr.src, rdr.pos);
-        rdr.pos = next.next;
+        let next = str::char_range_at(*rdr.src, rdr.pos.to_uint());
+        rdr.pos = BytePos(next.next);
         rdr.curr = next.ch;
     } else {
         if (rdr.curr != -1 as char) {
-            rdr.col += 1u;
-            rdr.chpos += 1u;
+            rdr.col += CharPos(1u);
+            rdr.chpos += CharPos(1u);
             rdr.curr = -1 as char;
         }
     }
@@ -153,8 +153,8 @@ fn is_eof(rdr: string_reader) -> bool {
     rdr.curr == -1 as char
 }
 fn nextch(rdr: string_reader) -> char {
-    if rdr.pos < (*rdr.src).len() {
-        return str::char_at(*rdr.src, rdr.pos);
+    if rdr.pos.to_uint() < (*rdr.src).len() {
+        return str::char_at(*rdr.src, rdr.pos.to_uint());
     } else { return -1 as char; }
 }
 
@@ -211,7 +211,7 @@ fn consume_any_line_comment(rdr: string_reader)
             bump(rdr);
             // line comments starting with "///" or "//!" are doc-comments
             if rdr.curr == '/' || rdr.curr == '!' {
-                let start_chpos = rdr.chpos - 2u;
+                let start_chpos = rdr.chpos - CharPos(2u);
                 let mut acc = ~"//";
                 while rdr.curr != '\n' && !is_eof(rdr) {
                     str::push_char(&mut acc, rdr.curr);
@@ -235,7 +235,7 @@ fn consume_any_line_comment(rdr: string_reader)
             let cmap = @CodeMap::new();
             (*cmap).files.push(rdr.filemap);
             let loc = cmap.lookup_char_pos_adj(rdr.chpos);
-            if loc.line == 1u && loc.col == 0u {
+            if loc.line == 1u && loc.col == CharPos(0u) {
                 while rdr.curr != '\n' && !is_eof(rdr) { bump(rdr); }
                 return consume_whitespace_and_comments(rdr);
             }
@@ -250,7 +250,7 @@ fn consume_block_comment(rdr: string_reader)
 
     // block comments starting with "/**" or "/*!" are doc-comments
     if rdr.curr == '*' || rdr.curr == '!' {
-        let start_chpos = rdr.chpos - 2u;
+        let start_chpos = rdr.chpos - CharPos(2u);
         let mut acc = ~"/*";
         while !(rdr.curr == '*' && nextch(rdr) == '/') && !is_eof(rdr) {
             str::push_char(&mut acc, rdr.curr);
@@ -584,7 +584,7 @@ fn next_token_inner(rdr: string_reader) -> token::Token {
         return token::LIT_INT(c2 as i64, ast::ty_char);
       }
       '"' => {
-        let n = rdr.chpos;
+        let n = rdr.pos;
         bump(rdr);
         while rdr.curr != '"' {
             if is_eof(rdr) {
diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs
index 43628b0908f..bd314d6bcaf 100644
--- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -5,7 +5,7 @@ use either::{Either, Left, Right};
 use std::map::HashMap;
 use token::{can_begin_expr, is_ident, is_ident_or_path, is_plain_ident,
             INTERPOLATED, special_idents};
-use codemap::{span,FssNone};
+use codemap::{span,FssNone, CharPos};
 use util::interner::Interner;
 use ast_util::{spanned, respan, mk_sp, ident_to_path, operator_prec};
 use lexer::reader;
@@ -244,7 +244,7 @@ impl Parser {
         self.token = next.tok;
         self.span = next.sp;
     }
-    fn swap(next: token::Token, lo: uint, hi: uint) {
+    fn swap(next: token::Token, +lo: CharPos, +hi: CharPos) {
         self.token = next;
         self.span = mk_sp(lo, hi);
     }
@@ -904,12 +904,12 @@ impl Parser {
         return spanned(lo, e.span.hi, {mutbl: m, ident: i, expr: e});
     }
 
-    fn mk_expr(lo: uint, hi: uint, +node: expr_) -> @expr {
+    fn mk_expr(+lo: CharPos, +hi: CharPos, +node: expr_) -> @expr {
         return @{id: self.get_id(), callee_id: self.get_id(),
               node: node, span: mk_sp(lo, hi)};
     }
 
-    fn mk_mac_expr(lo: uint, hi: uint, m: mac_) -> @expr {
+    fn mk_mac_expr(+lo: CharPos, +hi: CharPos, m: mac_) -> @expr {
         return @{id: self.get_id(),
               callee_id: self.get_id(),
               node: expr_mac({node: m, span: mk_sp(lo, hi)}),
@@ -1134,7 +1134,7 @@ impl Parser {
         return self.mk_expr(lo, hi, ex);
     }
 
-    fn parse_block_expr(lo: uint, blk_mode: blk_check_mode) -> @expr {
+    fn parse_block_expr(lo: CharPos, blk_mode: blk_check_mode) -> @expr {
         self.expect(token::LBRACE);
         let blk = self.parse_block_tail(lo, blk_mode);
         return self.mk_expr(blk.span.lo, blk.span.hi, expr_block(blk));
@@ -1146,7 +1146,7 @@ impl Parser {
         return self.parse_syntax_ext_naked(lo);
     }
 
-    fn parse_syntax_ext_naked(lo: uint) -> @expr {
+    fn parse_syntax_ext_naked(lo: CharPos) -> @expr {
         match self.token {
           token::IDENT(_, _) => (),
           _ => self.fatal(~"expected a syntax expander name")
@@ -2279,11 +2279,11 @@ impl Parser {
     // I guess that also means "already parsed the 'impure'" if
     // necessary, and this should take a qualifier.
     // some blocks start with "#{"...
-    fn parse_block_tail(lo: uint, s: blk_check_mode) -> blk {
+    fn parse_block_tail(lo: CharPos, s: blk_check_mode) -> blk {
         self.parse_block_tail_(lo, s, ~[])
     }
 
-    fn parse_block_tail_(lo: uint, s: blk_check_mode,
+    fn parse_block_tail_(lo: CharPos, s: blk_check_mode,
                          +first_item_attrs: ~[attribute]) -> blk {
         let mut stmts = ~[];
         let mut expr = None;
@@ -2581,7 +2581,7 @@ impl Parser {
         return {ident: id, tps: ty_params};
     }
 
-    fn mk_item(lo: uint, hi: uint, +ident: ident,
+    fn mk_item(+lo: CharPos, +hi: CharPos, +ident: ident,
                +node: item_, vis: visibility,
                +attrs: ~[attribute]) -> @item {
         return @{ident: ident,
@@ -3037,7 +3037,7 @@ impl Parser {
             items: items};
     }
 
-    fn parse_item_foreign_mod(lo: uint,
+    fn parse_item_foreign_mod(lo: CharPos,
                               visibility: visibility,
                               attrs: ~[attribute],
                               items_allowed: bool)
@@ -3092,7 +3092,7 @@ impl Parser {
         });
     }
 
-    fn parse_type_decl() -> {lo: uint, ident: ident} {
+    fn parse_type_decl() -> {lo: CharPos, ident: ident} {
         let lo = self.last_span.lo;
         let id = self.parse_ident();
         return {lo: lo, ident: id};
diff --git a/src/libsyntax/print/pprust.rs b/src/libsyntax/print/pprust.rs
index 8fa7543b2d1..910cb89ec75 100644
--- a/src/libsyntax/print/pprust.rs
+++ b/src/libsyntax/print/pprust.rs
@@ -1,5 +1,5 @@
 use parse::{comments, lexer, token};
-use codemap::CodeMap;
+use codemap::{CodeMap, CharPos};
 use pp::{break_offset, word, printer, space, zerobreak, hardbreak, breaks};
 use pp::{consistent, inconsistent, eof};
 use ast::{required, provided};
@@ -631,7 +631,7 @@ fn print_variants(s: ps, variants: ~[ast::variant], span: ast::span) {
         print_variant(s, *v);
         word(s.s, ~",");
         end(s);
-        maybe_print_trailing_comment(s, v.span, None::<uint>);
+        maybe_print_trailing_comment(s, v.span, None);
     }
     bclose(s, span);
 }
@@ -886,7 +886,7 @@ fn print_stmt(s: ps, st: ast::stmt) {
       }
     }
     if parse::classify::stmt_ends_with_semi(st) { word(s.s, ~";"); }
-    maybe_print_trailing_comment(s, st.span, None::<uint>);
+    maybe_print_trailing_comment(s, st.span, None);
 }
 
 fn print_block(s: ps, blk: ast::blk) {
@@ -1898,7 +1898,7 @@ fn print_ty_fn(s: ps,
 }
 
 fn maybe_print_trailing_comment(s: ps, span: codemap::span,
-                                next_pos: Option<uint>) {
+                                next_pos: Option<CharPos>) {
     let mut cm;
     match s.cm { Some(ccm) => cm = ccm, _ => return }
     match next_comment(s) {
@@ -1906,7 +1906,7 @@ fn maybe_print_trailing_comment(s: ps, span: codemap::span,
         if cmnt.style != comments::trailing { return; }
         let span_line = cm.lookup_char_pos(span.hi);
         let comment_line = cm.lookup_char_pos(cmnt.pos);
-        let mut next = cmnt.pos + 1u;
+        let mut next = cmnt.pos + CharPos(1u);
         match next_pos { None => (), Some(p) => next = p }
         if span.hi < cmnt.pos && cmnt.pos < next &&
                span_line.line == comment_line.line {
@@ -1981,7 +1981,7 @@ fn lit_to_str(l: @ast::lit) -> ~str {
     return to_str(l, print_literal, parse::token::mk_fake_ident_interner());
 }
 
-fn next_lit(s: ps, pos: uint) -> Option<comments::lit> {
+fn next_lit(s: ps, pos: CharPos) -> Option<comments::lit> {
     match s.literals {
       Some(lits) => {
         while s.cur_lit < vec::len(lits) {
@@ -1996,7 +1996,7 @@ fn next_lit(s: ps, pos: uint) -> Option<comments::lit> {
     }
 }
 
-fn maybe_print_comment(s: ps, pos: uint) {
+fn maybe_print_comment(s: ps, pos: CharPos) {
     loop {
         match next_comment(s) {
           Some(cmnt) => {