stdlib: Add module erl_anno

Introduce erl_anno, an abstraction of the second element of tokens and
tuples in the abstract format. The convention that negative line
numbers can be used for silencing compiler warnings will no longer
work in OTP 19; instead the annotation 'generated' is to be used.

10 files changed, 1600 insertions, 8 deletions

diff --git a/lib/stdlib/doc/src/Makefile b/lib/stdlib/doc/src/Makefile
index f5d8b2072a..ce1e19a2a4 100644
--- a/lib/stdlib/doc/src/Makefile
+++ b/lib/stdlib/doc/src/Makefile
@@ -1,7 +1,7 @@
 #
 # %CopyrightBegin%
 #
-# Copyright Ericsson AB 1997-2012. All Rights Reserved.
+# Copyright Ericsson AB 1997-2015. All Rights Reserved.
 #
 # The contents of this file are subject to the Erlang Public License,
 # Version 1.1, (the "License"); you may not use this file except in
@@ -48,6 +48,7 @@ XML_REF3_FILES = \
 	digraph.xml \
 	digraph_utils.xml \
 	epp.xml \
+	erl_anno.xml \
 	erl_eval.xml \
 	erl_expand_records.xml \
 	erl_id_trans.xml \
diff --git a/lib/stdlib/doc/src/erl_anno.xml b/lib/stdlib/doc/src/erl_anno.xml
new file mode 100644
index 0000000000..281feacdc4
--- /dev/null
+++ b/lib/stdlib/doc/src/erl_anno.xml
@@ -0,0 +1,308 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<!DOCTYPE erlref SYSTEM "erlref.dtd">
+
+<erlref>
+  <header>
+    <copyright>
+      <year>2015</year>
+      <year>2015</year>
+      <holder>Ericsson AB, All Rights Reserved</holder>
+    </copyright>
+    <legalnotice>
+  The contents of this file are subject to the Erlang Public License,
+  Version 1.1, (the "License"); you may not use this file except in
+  compliance with the License. You should have received a copy of the
+  Erlang Public License along with this software. If not, it can be
+  retrieved on line at http://www.erlang.org/.
+
+  Software distributed under the License is distributed on an "AS IS"
+  basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
+  the License for the specific language governing rights and limitations
+  under the License.
+
+  The Initial Developer of the Original Code is Ericsson AB.
+    </legalnotice>
+
+    <title>erl_anno</title>
+    <prepared>Hans Bolinder</prepared>
+    <responsible>Kenneth Lundin</responsible>
+    <docno>1</docno>
+    <approved></approved>
+    <checked></checked>
+    <date>2015-02-26</date>
+    <rev>A</rev>
+    <file>erl_anno.xml</file>
+  </header>
+  <module>erl_anno</module>
+
+  <modulesummary>
+    Abstract Datatype for the Annotations of the Erlang Compiler
+  </modulesummary>
+
+  <description>
+    <p>This module implements an abstract type that is used by the
+      Erlang Compiler and its helper modules for holding data such as
+      column, line number, and text. The data type is a collection of
+      <marker id="annotations"><em>annotations</em></marker> as
+      described in the following.</p>
+    <p>The Erlang Token Scanner returns tokens with a subset of
+      the following annotations, depending on the options:</p>
+    <taglist>
+      <tag><c>column</c></tag>
+      <item><p>The column where the token begins.</p></item>
+      <tag><c>location</c></tag>
+      <item><p>The line and column where the token begins, or
+        just the line if the column unknown.</p>
+      </item>
+      <tag><c>text</c></tag>
+      <item><p>The token's text.</p></item>
+    </taglist>
+    <p>From the above the following annotation is derived:</p>
+    <taglist>
+      <tag><c>line</c></tag>
+      <item><p>The line where the token begins.</p></item>
+    </taglist>
+    <p>Furthermore, the following annotations are supported by
+      this module, and used by various modules:</p>
+    <taglist>
+      <tag><c>file</c></tag>
+      <item><p>A filename.</p></item>
+      <tag><c>generated</c></tag>
+      <item><p>A Boolean indicating if the abstract code is
+        compiler generated. The Erlang Compiler does not emit warnings
+        for such code.</p>
+      </item>
+      <tag><c>record</c></tag>
+      <item><p>A Boolean indicating if the origin of the abstract
+        code is a record. Used by Dialyzer to assign types to tuple
+        elements.</p>
+      </item>
+    </taglist>
+    <p>The functions
+      <seealso marker="erl_scan#column/1">column()</seealso>,
+      <seealso marker="erl_scan#end_location/1">end_location()</seealso>,
+      <seealso marker="erl_scan#line/1">line()</seealso>,
+      <seealso marker="erl_scan#location/1">location()</seealso>, and
+      <seealso marker="erl_scan#text/1">text()</seealso>
+      in the <c>erl_scan</c> module can be used for inspecting
+      annotations in tokens.</p>
+    <p>The functions
+      <seealso marker="erl_parse#map_anno/2">map_anno()</seealso>,
+      <seealso marker="erl_parse#fold_anno/3">fold_anno()</seealso>,
+      <seealso marker="erl_parse#mapfold_anno/3">mapfold_anno()</seealso>,
+      <seealso marker="erl_parse#new_anno/1">new_anno()</seealso>,
+      <seealso marker="erl_parse#anno_from_term/1">
+      anno_from_term()</seealso>, and
+      <seealso marker="erl_parse#anno_to_term/1">
+      anno_to_term()</seealso> in the <c>erl_parse</c> module can be
+      used for manipulating annotations in abstract code.
+    </p>
+  </description>
+
+  <datatypes>
+    <datatype>
+      <name><marker id="type-anno">anno()</marker></name>
+      <desc><p>A collection of annotations.</p>
+      </desc>
+    </datatype>
+    <datatype>
+      <name name="anno_term"></name>
+      <desc>
+        <p>The term representing a collection of annotations. It is
+          either a <c>location()</c> or a list of key-value pairs.</p>
+      </desc>
+    </datatype>
+    <datatype>
+      <name name="column"></name>
+    </datatype>
+    <datatype>
+      <name name="line"></name>
+      <desc>
+      <p>To be changed to a non-negative integer in Erlang/OTP 19.0.</p>
+      </desc>
+    </datatype>
+    <datatype>
+      <name name="location"></name>
+    </datatype>
+    <datatype>
+      <name name="text"></name>
+    </datatype>
+  </datatypes>
+
+  <funcs>
+    <func>
+      <name name="column" arity="1"/>
+      <type name="column"></type>
+      <fsummary>Return the column</fsummary>
+      <desc>
+        <p>Returns the column of the annotations <anno>Anno</anno>.
+        </p>
+      </desc>
+    </func>
+    <func>
+      <name name="end_location" arity="1"/>
+      <type name="location"></type>
+      <fsummary>Return the end location of the text</fsummary>
+      <desc>
+        <p>Returns the end location of the text of the
+          annotations <anno>Anno</anno>. If there is no text,
+          <c>undefined</c> is returned.
+        </p>
+      </desc>
+    </func>
+    <func>
+      <name name="file" arity="1"/>
+      <type name="filename"></type>
+      <fsummary>Return the filename</fsummary>
+      <desc>
+        <p>Returns the filename of the annotations <anno>Anno</anno>.
+          If there is no filename, <c>undefined</c> is returned.
+        </p>
+      </desc>
+    </func>
+    <func>
+      <name name="from_term" arity="1"/>
+      <fsummary>Return annotations given a term</fsummary>
+      <desc>
+        <p>Returns annotations with the representation <anno>Term</anno>.
+        </p>
+        <!--
+        <p>Although it is possible to create new annotations by calling
+          <c>from_term/1</c>, the intention is that one should not do
+          so - the proper way to create annotations is to call
+          <c>new/1</c> and then modify the annotations
+          by calling the <c>set_*</c> functions.</p>
+        -->
+        <p>See also <seealso marker="#to_term/1">to_term()</seealso>.
+        </p>
+      </desc>
+    </func>
+    <func>
+      <name name="generated" arity="1"/>
+      <type name="generated"></type>
+      <fsummary>Return the generated Boolean</fsummary>
+      <desc>
+        <p>Returns <c>true</c> if the annotations <anno>Anno</anno>
+          has been marked as generated. The default is to return
+          <c>false</c>.
+        </p>
+      </desc>
+    </func>
+    <func>
+      <name name="is_anno" arity="1"/>
+      <fsummary>Test for a collection of annotations</fsummary>
+      <desc>
+        <p>Returns <c>true</c> if <anno>Term</anno> is a collection of
+          annotations, <c>false</c> otherwise.</p>
+      </desc>
+    </func>
+    <func>
+      <name name="line" arity="1"/>
+      <type name="line"></type>
+      <fsummary>Return the line</fsummary>
+      <desc>
+        <p>Returns the line of the annotations <anno>Anno</anno>.
+        </p>
+      </desc>
+    </func>
+    <func>
+      <name name="location" arity="1"/>
+      <type name="location"></type>
+      <fsummary>Return the location</fsummary>
+      <desc>
+        <p>Returns the location of the annotations <anno>Anno</anno>.
+        </p>
+      </desc>
+    </func>
+    <func>
+      <name name="new" arity="1"/>
+      <type name="location"></type>
+      <fsummary>Create a new collection of annotations</fsummary>
+      <desc>
+        <p>Creates a new collection of annotations given a location.</p>
+      </desc>
+    </func>
+    <func>
+      <name name="set_file" arity="2"/>
+      <type name="filename"></type>
+      <fsummary>Modify the filename</fsummary>
+      <desc>
+        <p>Modifies the filename of the annotations <anno>Anno</anno>.
+        </p>
+      </desc>
+    </func>
+    <func>
+      <name name="set_generated" arity="2"/>
+      <type name="generated"></type>
+      <fsummary>Modify the generated marker</fsummary>
+      <desc>
+        <p>Modifies the generated marker of the annotations
+          <anno>Anno</anno>.
+        </p>
+      </desc>
+    </func>
+    <func>
+      <name name="set_line" arity="2"/>
+      <type name="line"></type>
+      <fsummary>Modify the line</fsummary>
+      <desc>
+        <p>Modifies the line of the annotations <anno>Anno</anno>.
+        </p>
+      </desc>
+    </func>
+    <func>
+      <name name="set_location" arity="2"/>
+      <type name="location"></type>
+      <fsummary>Modify the location</fsummary>
+      <desc>
+        <p>Modifies the location of the annotations <anno>Anno</anno>.
+        </p>
+      </desc>
+    </func>
+    <func>
+      <name name="set_record" arity="2"/>
+      <type name="record"></type>
+      <fsummary>Modify the record marker</fsummary>
+      <desc>
+        <p>Modifies the record marker of the annotations <anno>Anno</anno>.
+        </p>
+      </desc>
+    </func>
+    <func>
+      <name name="set_text" arity="2"/>
+      <type name="text"></type>
+      <fsummary>Modify the text</fsummary>
+      <desc>
+        <p>Modifies the text of the annotations <anno>Anno</anno>.
+        </p>
+      </desc>
+    </func>
+    <func>
+      <name name="text" arity="1"/>
+      <type name="text"></type>
+      <fsummary>Return the text</fsummary>
+      <desc>
+        <p>Returns the text of the annotations <anno>Anno</anno>.
+        If there is no text, <c>undefined</c> is returned.
+        </p>
+      </desc>
+    </func>
+    <func>
+      <name name="to_term" arity="1"/>
+      <fsummary>Return the term representing a collection of
+        annotations</fsummary>
+      <desc>
+        <p>Returns the term representing the annotations <anno>Anno</anno>.
+        </p>
+        <p>See also <seealso marker="#from_term/1">from_term()</seealso>.
+        </p>
+      </desc>
+    </func>
+  </funcs>
+  <section>
+    <title>See Also</title>
+    <p><seealso marker="erl_scan">erl_scan(3)</seealso>,
+       <seealso marker="erl_parse">erl_parse(3)</seealso>
+    </p>
+  </section>
+</erlref>
diff --git a/lib/stdlib/doc/src/erl_parse.xml b/lib/stdlib/doc/src/erl_parse.xml
index cf0bff48cd..b97d06e919 100644
--- a/lib/stdlib/doc/src/erl_parse.xml
+++ b/lib/stdlib/doc/src/erl_parse.xml
@@ -4,7 +4,7 @@
 <erlref>
   <header>
     <copyright>
-      <year>1996</year><year>2014</year>
+      <year>1996</year><year>2015</year>
       <holder>Ericsson AB. All Rights Reserved.</holder>
     </copyright>
     <legalnotice>
@@ -192,6 +192,97 @@
           considered a string.</p>
       </desc>
     </func>
+    <func>
+      <name name="map_anno" arity="2"/>
+      <fsummary>
+        Map a function over the annotations of an abstract form
+      </fsummary>
+      <desc>
+        <p>Modifies the abstract form <anno>Abstr</anno> by applying
+          <anno>Fun</anno> on every collection of annotations of the
+          abstract form. The abstract form is traversed in a
+          depth-first, left-to-right, fashion.
+        </p>
+      </desc>
+    </func>
+    <func>
+      <name name="fold_anno" arity="3"/>
+      <fsummary>
+        Fold a function over the annotations of an abstract form
+      </fsummary>
+      <desc>
+        <p>Updates an accumulator by applying <anno>Fun</anno> on
+          every collection of annotations of the abstract form
+          <anno>Abstr</anno>. The first call to <anno>Fun</anno> has
+          <anno>AccIn</anno> as argument, and the returned accumulator
+          <anno>AccOut</anno> is passed to the next call, and so on.
+          The final value of the accumulator is returned. The abstract
+          form is traversed in a depth-first, left-to-right, fashion.
+        </p>
+      </desc>
+    </func>
+    <func>
+      <name name="mapfold_anno" arity="3"/>
+      <fsummary>
+        Map and fold a function over the annotations of an abstract form
+      </fsummary>
+      <desc>
+        <p>Modifies the abstract form <anno>Abstr</anno> by applying
+          <anno>Fun</anno> on every collection of annotations of the
+          abstract form, while at the same time updating an
+          accumulator. The first call to <anno>Fun</anno> has
+          <anno>AccIn</anno> as second argument, and the returned
+          accumulator <anno>AccOut</anno> is passed to the next call,
+          and so on. The modified abstract form as well as the the
+          final value of the accumulator is returned. The abstract
+          form is traversed in a depth-first, left-to-right, fashion.
+        </p>
+      </desc>
+    </func>
+    <func>
+      <name name="new_anno" arity="1"/>
+      <fsummary>
+        Create new annotations
+      </fsummary>
+      <desc>
+        <p>Creates an abstract form from a term which has the same
+          structure as an abstract form, but <seealso
+          marker="erl_anno#type-location">locations</seealso> where the
+          abstract form has annotations. For each location, <seealso
+          marker="erl_anno#new/1"><c>erl_anno:new/1</c></seealso> is
+          called, and the annotations replace the location.
+        </p>
+      </desc>
+    </func>
+    <func>
+      <name name="anno_from_term" arity="1"/>
+      <fsummary>
+        Return annotations as terms
+      </fsummary>
+      <desc>
+        <p>Assumes that <anno>Term</anno> is a term with the same
+          structure as an abstract form, but with terms, T say, on
+          those places where an abstract form has annotations. Returns
+          an abstract form where every term T has been replaced by the
+          value returned by calling <c>erl_anno:from_term(T)</c>. The
+          term <anno>Term</anno> is traversed in a depth-first,
+          left-to-right, fashion.
+        </p>
+      </desc>
+    </func>
+    <func>
+      <name name="anno_to_term" arity="1"/>
+      <fsummary>
+        Return the representation of annotations
+      </fsummary>
+      <desc>
+        <p>Returns a term where every collection of annotations Anno of
+          <anno>Abstr</anno> has been replaced by the term returned by
+          calling <c>erl_anno:to_term(Anno)</c>. The abstract form is
+          traversed in a depth-first, left-to-right, fashion.
+        </p>
+      </desc>
+    </func>
   </funcs>
 
   <section>
@@ -211,8 +302,9 @@
   <section>
     <title>See Also</title>
     <p><seealso marker="io">io(3)</seealso>,
-      <seealso marker="erl_scan">erl_scan(3)</seealso>,
-      ERTS User's Guide</p>
+       <seealso marker="erl_anno">erl_anno(3)</seealso>,
+       <seealso marker="erl_scan">erl_scan(3)</seealso>,
+       <seealso marker="erts:absform">ERTS User's Guide</seealso></p>
   </section>
 </erlref>
 
diff --git a/lib/stdlib/doc/src/ref_man.xml b/lib/stdlib/doc/src/ref_man.xml
index ea4009dc3e..94c1fb55c2 100644
--- a/lib/stdlib/doc/src/ref_man.xml
+++ b/lib/stdlib/doc/src/ref_man.xml
@@ -4,7 +4,7 @@
 <application xmlns:xi="http://www.w3.org/2001/XInclude">
   <header>
     <copyright>
-      <year>1996</year><year>2013</year>
+      <year>1996</year><year>2015</year>
       <holder>Ericsson AB. All Rights Reserved.</holder>
     </copyright>
     <legalnotice>
@@ -45,6 +45,7 @@
   <xi:include href="digraph.xml"/>
   <xi:include href="digraph_utils.xml"/>
   <xi:include href="epp.xml"/>
+  <xi:include href="erl_anno.xml"/>
   <xi:include href="erl_eval.xml"/>
   <xi:include href="erl_expand_records.xml"/>
   <xi:include href="erl_id_trans.xml"/>
diff --git a/lib/stdlib/doc/src/specs.xml b/lib/stdlib/doc/src/specs.xml
index fd77b52da6..6ae0154800 100644
--- a/lib/stdlib/doc/src/specs.xml
+++ b/lib/stdlib/doc/src/specs.xml
@@ -11,6 +11,7 @@
   <xi:include href="../specs/specs_digraph.xml"/>
   <xi:include href="../specs/specs_digraph_utils.xml"/>
   <xi:include href="../specs/specs_epp.xml"/>
+  <xi:include href="../specs/specs_erl_anno.xml"/>
   <xi:include href="../specs/specs_erl_eval.xml"/>
   <xi:include href="../specs/specs_erl_expand_records.xml"/>
   <xi:include href="../specs/specs_erl_id_trans.xml"/>
diff --git a/lib/stdlib/src/Makefile b/lib/stdlib/src/Makefile
index 1b3744b6fb..baa178e624 100644
--- a/lib/stdlib/src/Makefile
+++ b/lib/stdlib/src/Makefile
@@ -1,7 +1,7 @@
 #
 # %CopyrightBegin%
 #
-# Copyright Ericsson AB 1996-2013. All Rights Reserved.
+# Copyright Ericsson AB 1996-2015. All Rights Reserved.
 #
 # The contents of this file are subject to the Erlang Public License,
 # Version 1.1, (the "License"); you may not use this file except in
@@ -58,6 +58,7 @@ MODULES= \
 	edlin \
 	edlin_expand \
 	epp \
+	erl_anno \
 	erl_bits \
 	erl_compile \
 	erl_eval \
diff --git a/lib/stdlib/src/erl_anno.erl b/lib/stdlib/src/erl_anno.erl
new file mode 100644
index 0000000000..963b7278a6
--- /dev/null
+++ b/lib/stdlib/src/erl_anno.erl
@@ -0,0 +1,460 @@
+%%
+%% %CopyrightBegin%
+%%
+%% Copyright Ericsson AB 1996-2015. All Rights Reserved.
+%%
+%% The contents of this file are subject to the Erlang Public License,
+%% Version 1.1, (the "License"); you may not use this file except in
+%% compliance with the License. You should have received a copy of the
+%% Erlang Public License along with this software. If not, it can be
+%% retrieved online at http://www.erlang.org/.
+%%
+%% Software distributed under the License is distributed on an "AS IS"
+%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
+%% the License for the specific language governing rights and limitations
+%% under the License.
+%%
+%% %CopyrightEnd%
+%%
+
+-module(erl_anno).
+
+-export([new/1, is_anno/1]).
+-export([column/1, end_location/1, file/1, generated/1,
+         line/1, location/1, record/1, text/1]).
+-export([set_file/2, set_generated/2, set_line/2, set_location/2,
+         set_record/2, set_text/2]).
+
+%% To be used when necessary to avoid Dialyzer warnings.
+-export([to_term/1, from_term/1]).
+
+-export_type([anno/0, line/0, column/0, location/0, text/0]).
+
+-export_type([anno_term/0]).
+
+-define(LN(L), is_integer(L)).
+-define(COL(C), (is_integer(C) andalso C >= 1)).
+
+%% Location.
+-define(LCOLUMN(C), ?COL(C)).
+-define(LLINE(L), ?LN(L)).
+
+%% Debug: define DEBUG to make sure that annotations are handled as an
+%% opaque type. Note that all abstract code need to be compiled with
+%% DEBUG=true. See also ./erl_pp.erl.
+
+%-define(DEBUG, true).
+
+-type annotation() :: {'file', filename()}
+                    | {'generated', generated()}
+                    | {'location', location()}
+                    | {'record', record()}
+                    | {'text', string()}.
+
+-type anno() :: location() | [annotation(), ...].
+-type anno_term() :: term().
+
+-type column() :: pos_integer().
+-type generated() :: boolean().
+-type filename() :: file:filename_all().
+-type line() :: integer().
+-type location() :: line() | {line(), column()}.
+-type record() :: boolean().
+-type text() :: string().
+
+-ifdef(DEBUG).
+%% Anything 'false' accepted by the compiler.
+-define(ALINE(A), is_reference(A)).
+-define(ACOLUMN(A), is_reference(A)).
+-else.
+-define(ALINE(L), ?LN(L)).
+-define(ACOLUMN(C), ?COL(C)).
+-endif.
+
+-spec to_term(Anno) -> anno_term() when
+      Anno :: anno().
+
+-ifdef(DEBUG).
+to_term(Anno) ->
+    simplify(Anno).
+-else.
+to_term(Anno) ->
+    Anno.
+-endif.
+
+-spec from_term(Term) -> Anno when
+      Term :: anno_term(),
+      Anno :: anno().
+
+-ifdef(DEBUG).
+from_term(Term) when is_list(Term) ->
+    Term;
+from_term(Term) ->
+    [{location, Term}].
+-else.
+from_term(Term) ->
+    Term.
+-endif.
+
+-spec new(Location) -> anno() when
+      Location :: location().
+
+new(Line) when ?LLINE(Line) ->
+    new_location(Line);
+new({Line, Column}=Loc) when ?LLINE(Line), ?LCOLUMN(Column) ->
+    new_location(Loc);
+new(Term) ->
+    erlang:error(badarg, [Term]).
+
+-ifdef(DEBUG).
+new_location(Location) ->
+    [{location, Location}].
+-else.
+new_location(Location) ->
+    Location.
+-endif.
+
+-spec is_anno(Term) -> boolean() when
+      Term :: any().
+
+is_anno(Line) when ?ALINE(Line) ->
+    true;
+is_anno({Line, Column}) when ?ALINE(Line), ?ACOLUMN(Column) ->
+    true;
+is_anno(Anno) ->
+    (Anno =/= [] andalso
+     is_anno1(Anno) andalso
+     lists:keymember(location, 1, Anno)).
+
+is_anno1([{Item, Value}|Anno]) ->
+    is_anno2(Item, Value) andalso is_anno1(Anno);
+is_anno1(A) ->
+    A =:= [].
+
+is_anno2(location, Line) when ?LN(Line) ->
+    true;
+is_anno2(location, {Line, Column}) when ?LN(Line), ?COL(Column) ->
+    true;
+is_anno2(generated, true) ->
+    true;
+is_anno2(file, Filename) ->
+    is_filename(Filename);
+is_anno2(record, true) ->
+    true;
+is_anno2(text, Text) ->
+    is_string(Text);
+is_anno2(_, _) ->
+    false.
+
+is_filename(T) ->
+    is_string(T) orelse is_binary(T).
+
+is_string(T) ->
+    try lists:all(fun(C) when is_integer(C), C >= 0 -> true end, T)
+    catch _:_ -> false
+    end.
+
+-spec column(Anno) -> column() | 'undefined' when
+      Anno :: anno().
+
+column({Line, Column}) when ?ALINE(Line), ?ACOLUMN(Column) ->
+    Column;
+column(Line) when ?ALINE(Line) ->
+    undefined;
+column(Anno) ->
+    case location(Anno) of
+        {_Line, Column} ->
+            Column;
+        _Line ->
+            undefined
+    end.
+
+-spec end_location(Anno) -> location() | 'undefined' when
+      Anno :: anno().
+
+end_location(Anno) ->
+    case text(Anno) of
+        undefined ->
+            undefined;
+        Text ->
+            case location(Anno) of
+                {Line, Column} ->
+                    end_location(Text, Line, Column);
+                Line ->
+                    end_location(Text, Line)
+            end
+    end.
+
+-spec file(Anno) -> filename() | 'undefined' when
+      Anno :: anno().
+
+file(Line) when ?ALINE(Line) ->
+    undefined;
+file({Line, Column}) when ?ALINE(Line), ?ACOLUMN(Column) ->
+    undefined;
+file(Anno) ->
+    anno_info(Anno, file).
+
+-spec generated(Anno) -> generated() when
+      Anno :: anno().
+
+generated(Line) when ?ALINE(Line) ->
+    Line =< 0;
+generated({Line, Column}) when ?ALINE(Line), ?ACOLUMN(Column) ->
+    Line =< 0;
+generated(Anno) ->
+    _ = anno_info(Anno, generated, false),
+    {location, Location} = lists:keyfind(location, 1, Anno),
+    case Location of
+        {Line, _Column} ->
+            Line =< 0;
+        Line ->
+            Line =< 0
+    end.
+
+-spec line(Anno) -> line() when
+      Anno :: anno().
+
+line(Anno) ->
+    case location(Anno) of
+        {Line, _Column} ->
+            Line;
+        Line ->
+            Line
+    end.
+
+-spec location(Anno) -> location() when
+      Anno :: anno().
+
+location(Line) when ?ALINE(Line) ->
+    abs(Line);
+location({Line, Column}) when ?ALINE(Line), ?ACOLUMN(Column) ->
+    {abs(Line), Column};
+location(Anno) ->
+    case anno_info(Anno, location) of
+        Line when Line < 0 ->
+            -Line;
+        {Line, Column} when Line < 0 ->
+            {-Line, Column};
+        Location ->
+            Location
+    end.
+
+-spec record(Anno) -> record() when
+      Anno :: anno().
+
+record(Line) when ?ALINE(Line) ->
+    false;
+record({Line, Column}) when ?ALINE(Line), ?ACOLUMN(Column) ->
+    false;
+record(Anno) ->
+    anno_info(Anno, record, false).
+
+-spec text(Anno) -> text() | 'undefined' when
+      Anno :: anno().
+
+text(Line) when ?ALINE(Line) ->
+    undefined;
+text({Line, Column}) when ?ALINE(Line), ?ACOLUMN(Column) ->
+    undefined;
+text(Anno) ->
+    anno_info(Anno, text).
+
+-spec set_file(File, Anno) -> Anno when
+      File :: filename(),
+      Anno :: anno().
+
+set_file(File, Anno) ->
+    set(file, File, Anno).
+
+-spec set_generated(Generated, Anno) -> Anno when
+      Generated :: generated(),
+      Anno :: anno().
+
+set_generated(true, Line) when ?ALINE(Line) ->
+    -abs(Line);
+set_generated(false, Line) when ?ALINE(Line) ->
+    abs(Line);
+set_generated(true, {Line, Column}) when ?ALINE(Line),
+                                         ?ACOLUMN(Column) ->
+    {-abs(Line),Column};
+set_generated(false, {Line, Column}) when ?ALINE(Line),
+                                          ?ACOLUMN(Column) ->
+    {abs(Line),Column};
+set_generated(Generated, Anno) ->
+    _ = set(generated, Generated, Anno),
+    {location, Location} = lists:keyfind(location, 1, Anno),
+    NewLocation =
+        case Location of
+            {Line, Column} when Generated ->
+                {-abs(Line), Column};
+            {Line, Column} when not Generated ->
+                {abs(Line), Column};
+            Line when Generated ->
+                -abs(Line);
+            Line when not Generated ->
+                abs(Line)
+        end,
+    lists:keyreplace(location, 1, Anno, {location, NewLocation}).
+
+-spec set_line(Line, Anno) -> Anno when
+      Line :: line(),
+      Anno :: anno().
+
+set_line(Line, Anno) ->
+    case location(Anno) of
+        {_Line, Column} ->
+            set_location({Line, Column}, Anno);
+        _Line ->
+            set_location(Line, Anno)
+    end.
+
+-spec set_location(Location, Anno) -> Anno when
+      Location :: location(),
+      Anno :: anno().
+
+set_location(Line, L) when ?ALINE(L), ?LLINE(Line) ->
+    new_location(fix_line(Line, L));
+set_location(Line, {L, Column}) when ?ALINE(L), ?ACOLUMN(Column),
+                                     ?LLINE(Line) ->
+    new_location(fix_line(Line, L));
+set_location({L, C}=Loc, Line) when ?ALINE(Line), ?LLINE(L), ?LCOLUMN(C) ->
+    new_location(fix_location(Loc, Line));
+set_location({L, C}=Loc, {Line, Column}) when ?ALINE(Line), ?ACOLUMN(Column),
+                                              ?LLINE(L), ?LCOLUMN(C) ->
+    new_location(fix_location(Loc, Line));
+set_location(Location, Anno) ->
+    _ = set(location, Location, Anno),
+    {location, OldLocation} = lists:keyfind(location, 1, Anno),
+    NewLocation =
+        case {Location, OldLocation} of
+            {{_Line, _Column}=Loc, {L, _C}} ->
+                fix_location(Loc, L);
+            {Line, {L, _C}} ->
+                fix_line(Line, L);
+            {{_Line, _Column}=Loc, L} ->
+                fix_location(Loc, L);
+            {Line, L} ->
+                fix_line(Line, L)
+        end,
+    lists:keyreplace(location, 1, Anno, {location, NewLocation}).
+
+fix_location({Line, Column}, OldLine) ->
+    {fix_line(Line, OldLine), Column}.
+
+fix_line(Line, OldLine) when OldLine < 0, Line > 0 ->
+    -Line;
+fix_line(Line, _OldLine) ->
+    Line.
+
+-spec set_record(Record, Anno) -> Anno when
+      Record :: record(),
+      Anno :: anno().
+
+set_record(Record, Anno) ->
+    set(record, Record, Anno).
+
+-spec set_text(Text, Anno) -> Anno when
+      Text :: text(),
+      Anno :: anno().
+
+set_text(Text, Anno) ->
+    set(text, Text, Anno).
+
+set(Item, Value, Anno) ->
+    case {is_settable(Item, Value), Anno} of
+        {true, Line} when ?ALINE(Line) ->
+            set_anno(Item, Value, [{location, Line}]);
+        {true, {L, C}=Location} when ?ALINE(L), ?ACOLUMN(C) ->
+            set_anno(Item, Value, [{location, Location}]);
+        {true, A} when is_list(A), A =/= [] ->
+            set_anno(Item, Value, Anno);
+        _ ->
+            erlang:error(badarg, [Item, Value, Anno])
+    end.
+
+set_anno(Item, Value, Anno) ->
+    case default(Item, Value) of
+        true ->
+            reset(Anno, Item);
+        false ->
+            R = case anno_info(Anno, Item) of
+                    undefined ->
+                        [{Item, Value}|Anno];
+                    _ ->
+                        lists:keyreplace(Item, 1, Anno, {Item, Value})
+                end,
+            simplify(R)
+    end.
+
+reset(Anno, Item) ->
+    A = lists:keydelete(Item, 1, Anno),
+    reset_simplify(A).
+
+-ifdef(DEBUG).
+reset_simplify(A) ->
+    A.
+-else.
+reset_simplify(A) ->
+    simplify(A).
+-endif.
+
+simplify([{location, Location}]) ->
+    Location;
+simplify(Anno) ->
+    Anno.
+
+anno_info(Anno, Item, Default) ->
+    try lists:keyfind(Item, 1, Anno) of
+        false ->
+            Default;
+        {Item, Value} ->
+            Value
+    catch
+        _:_ ->
+            erlang:error(badarg, [Anno])
+    end.
+
+anno_info(Anno, Item) ->
+    try lists:keyfind(Item, 1, Anno) of
+        {Item, Value} ->
+            Value;
+        false ->
+            undefined
+    catch
+        _:_ ->
+            erlang:error(badarg, [Anno])
+    end.
+
+end_location("", Line, Column) ->
+    {Line, Column};
+end_location([$\n|String], Line, _Column) ->
+    end_location(String, Line+1, 1);
+end_location([_|String], Line, Column) ->
+    end_location(String, Line, Column+1).
+
+end_location("", Line) ->
+    Line;
+end_location([$\n|String], Line) ->
+    end_location(String, Line+1);
+end_location([_|String], Line) ->
+    end_location(String, Line).
+
+is_settable(file, File) ->
+    is_filename(File);
+is_settable(generated, Boolean) when Boolean; not Boolean ->
+    true;
+is_settable(location, Line) when ?LLINE(Line) ->
+    true;
+is_settable(location, {Line, Column}) when ?LLINE(Line), ?LCOLUMN(Column) ->
+    true;
+is_settable(record, Boolean) when Boolean; not Boolean ->
+    true;
+is_settable(text, Text) ->
+    is_string(Text);
+is_settable(_, _) ->
+    false.
+
+default(generated, false) -> true;
+default(record, false) -> true;
+default(_, _) -> false.
diff --git a/lib/stdlib/src/erl_parse.yrl b/lib/stdlib/src/erl_parse.yrl
index 3502a50eaa..b7469a05da 100644
--- a/lib/stdlib/src/erl_parse.yrl
+++ b/lib/stdlib/src/erl_parse.yrl
@@ -2,7 +2,7 @@
 %%
 %% %CopyrightBegin%
 %%
-%% Copyright Ericsson AB 1996-2014. All Rights Reserved.
+%% Copyright Ericsson AB 1996-2015. All Rights Reserved.
 %%
 %% The contents of this file are subject to the Erlang Public License,
 %% Version 1.1, (the "License"); you may not use this file except in
@@ -524,6 +524,8 @@ Erlang code.
 -export([normalise/1,abstract/1,tokens/1,tokens/2]).
 -export([abstract/2]).
 -export([inop_prec/1,preop_prec/1,func_prec/0,max_prec/0]).
+-export([map_anno/2, fold_anno/3, mapfold_anno/3,
+         new_anno/1, anno_to_term/1, anno_from_term/1]).
 -export([set_line/2,get_attribute/2,get_attributes/1]).
 
 %% The following directive is needed for (significantly) faster compilation
@@ -533,6 +535,7 @@ Erlang code.
 -export_type([abstract_clause/0, abstract_expr/0, abstract_form/0,
               error_info/0]).
 
+%% XXX. To be refined.
 -type abstract_clause() :: term().
 -type abstract_expr() :: term().
 -type abstract_form() :: term().
@@ -1101,4 +1104,159 @@ get_attribute(L, Name) ->
 get_attributes(L) ->
     erl_scan:attributes_info(L).
 
+-spec map_anno(Fun, Abstr) -> NewAbstr when
+      Fun :: fun((Anno) -> Anno),
+      Anno :: erl_anno:anno(),
+      Abstr :: abstract_form() | abstract_expr(),
+      NewAbstr :: abstract_form() | abstract_expr().
+
+map_anno(F0, Abstr) ->
+    F = fun(A, Acc) -> {F0(A), Acc} end,
+    {NewAbstr, []} = modify_anno1(Abstr, [], F),
+    NewAbstr.
+
+-spec fold_anno(Fun, Acc0, Abstr) -> NewAbstr when
+      Fun :: fun((Anno, AccIn) -> AccOut),
+      Anno :: erl_anno:anno(),
+      Acc0 :: term(),
+      AccIn :: term(),
+      AccOut :: term(),
+      Abstr :: abstract_form() | abstract_expr(),
+      NewAbstr :: abstract_form() | abstract_expr().
+
+fold_anno(F0, Acc0, Abstr) ->
+    F = fun(A, Acc) -> {A, F0(A, Acc)} end,
+    {_, NewAcc} = modify_anno1(Abstr, Acc0, F),
+    NewAcc.
+
+-spec mapfold_anno(Fun, Acc0, Abstr) -> {NewAbstr, Acc1} when
+      Fun :: fun((Anno, AccIn) -> {Anno, AccOut}),
+      Anno :: erl_anno:anno(),
+      Acc0 :: term(),
+      Acc1 :: term(),
+      AccIn :: term(),
+      AccOut :: term(),
+      Abstr :: abstract_form() | abstract_expr(),
+      NewAbstr :: abstract_form() | abstract_expr().
+
+mapfold_anno(F, Acc0, Abstr) ->
+    modify_anno1(Abstr, Acc0, F).
+
+-spec new_anno(Term) -> Abstr when
+      Term :: term(),
+      Abstr :: abstract_form() | abstract_expr().
+
+new_anno(Term) ->
+    F = fun(Loc) -> erl_anno:new(Loc) end,
+    map_anno(F, Term).
+
+-spec anno_to_term(Abstr) -> term() when
+      Abstr :: abstract_form() | abstract_expr().
+
+anno_to_term(Abstract) ->
+    F = fun(Anno) -> erl_anno:to_term(Anno) end,
+    map_anno(F, Abstract).
+
+-spec anno_from_term(Term) -> abstract_form() | abstract_expr() when
+      Term :: term().
+
+anno_from_term(Term) ->
+    F = fun(T) -> erl_anno:from_term(T) end,
+    map_anno(F, Term).
+
+%% Forms.
+%% Recognize what sys_pre_expand does:
+modify_anno1({'fun',A,F,{_,_,_}=Id}, Ac, Mf) ->
+    {A1,Ac1} = Mf(A, Ac),
+    {F1,Ac2} = modify_anno1(F, Ac1, Mf),
+    {{'fun',A1,F1,Id},Ac2};
+modify_anno1({named_fun,A,N,F,{_,_,_}=Id}, Ac, Mf) ->
+    {A1,Ac1} = Mf(A, Ac),
+    {F1,Ac2} = modify_anno1(F, Ac1, Mf),
+    {{named_fun,A1,N,F1,Id},Ac2};
+modify_anno1({attribute,A,N,[V]}, Ac, Mf) ->
+    {{attribute,A1,N1,V1},Ac1} = modify_anno1({attribute,A,N,V}, Ac, Mf),
+    {{attribute,A1,N1,[V1]},Ac1};
+%% End of sys_pre_expand special forms.
+modify_anno1({function,F,A}, Ac, _Mf) ->
+    {{function,F,A},Ac};
+modify_anno1({function,M,F,A}, Ac, Mf) ->
+    {M1,Ac1} = modify_anno1(M, Ac, Mf),
+    {F1,Ac2} = modify_anno1(F, Ac1, Mf),
+    {A1,Ac3} = modify_anno1(A, Ac2, Mf),
+    {{function,M1,F1,A1},Ac3};
+modify_anno1({attribute,A,record,{Name,Fields}}, Ac, Mf) ->
+    {A1,Ac1} = Mf(A, Ac),
+    {Fields1,Ac2} = modify_anno1(Fields, Ac1, Mf),
+    {{attribute,A1,record,{Name,Fields1}},Ac2};
+modify_anno1({attribute,A,spec,{Fun,Types}}, Ac, Mf) ->
+    {A1,Ac1} = Mf(A, Ac),
+    {Types1,Ac2} = modify_anno1(Types, Ac1, Mf),
+    {{attribute,A1,spec,{Fun,Types1}},Ac2};
+modify_anno1({attribute,A,callback,{Fun,Types}}, Ac, Mf) ->
+    {A1,Ac1} = Mf(A, Ac),
+    {Types1,Ac2} = modify_anno1(Types, Ac1, Mf),
+    {{attribute,A1,callback,{Fun,Types1}},Ac2};
+modify_anno1({attribute,A,type,{TypeName,TypeDef,Args}}, Ac, Mf) ->
+    {A1,Ac1} = Mf(A, Ac),
+    {TypeDef1,Ac2} = modify_anno1(TypeDef, Ac1, Mf),
+    {Args1,Ac3} = modify_anno1(Args, Ac2, Mf),
+    {{attribute,A1,type,{TypeName,TypeDef1,Args1}},Ac3};
+modify_anno1({attribute,A,opaque,{TypeName,TypeDef,Args}}, Ac, Mf) ->
+    {A1,Ac1} = Mf(A, Ac),
+    {TypeDef1,Ac2} = modify_anno1(TypeDef, Ac1, Mf),
+    {Args1,Ac3} = modify_anno1(Args, Ac2, Mf),
+    {{attribute,A1,opaque,{TypeName,TypeDef1,Args1}},Ac3};
+modify_anno1({attribute,A,Attr,Val}, Ac, Mf) ->
+    {A1,Ac1} = Mf(A, Ac),
+    {{attribute,A1,Attr,Val},Ac1};
+modify_anno1({warning,W}, Ac, _Mf) ->
+    {{warning,W},Ac};
+modify_anno1({error,W}, Ac, _Mf) ->
+    {{error,W},Ac};
+%% Expressions.
+modify_anno1({clauses,Cs}, Ac, Mf) ->
+    {Cs1,Ac1} = modify_anno1(Cs, Ac, Mf),
+    {{clauses,Cs1},Ac1};
+modify_anno1({typed_record_field,Field,Type}, Ac, Mf) ->
+    {Field1,Ac1} = modify_anno1(Field, Ac, Mf),
+    {Type1,Ac2} = modify_anno1(Type, Ac1, Mf),
+    {{typed_record_field,Field1,Type1},Ac2};
+modify_anno1({Tag,A}, Ac, Mf) ->
+    {A1,Ac1} = Mf(A, Ac),
+    {{Tag,A1},Ac1};
+modify_anno1({Tag,A,E1}, Ac, Mf) ->
+    {A1,Ac1} = Mf(A, Ac),
+    {E11,Ac2} = modify_anno1(E1, Ac1, Mf),
+    {{Tag,A1,E11},Ac2};
+modify_anno1({Tag,A,E1,E2}, Ac, Mf) ->
+    {A1,Ac1} = Mf(A, Ac),
+    {E11,Ac2} = modify_anno1(E1, Ac1, Mf),
+    {E21,Ac3} = modify_anno1(E2, Ac2, Mf),
+    {{Tag,A1,E11,E21},Ac3};
+modify_anno1({bin_element,A,E1,E2,TSL}, Ac, Mf) ->
+    {A1,Ac1} = Mf(A, Ac),
+    {E11,Ac2} = modify_anno1(E1, Ac1, Mf),
+    {E21,Ac3} = modify_anno1(E2, Ac2, Mf),
+    {{bin_element,A1,E11,E21, TSL},Ac3};
+modify_anno1({Tag,A,E1,E2,E3}, Ac, Mf) ->
+    {A1,Ac1} = Mf(A, Ac),
+    {E11,Ac2} = modify_anno1(E1, Ac1, Mf),
+    {E21,Ac3} = modify_anno1(E2, Ac2, Mf),
+    {E31,Ac4} = modify_anno1(E3, Ac3, Mf),
+    {{Tag,A1,E11,E21,E31},Ac4};
+modify_anno1({Tag,A,E1,E2,E3,E4}, Ac, Mf) ->
+    {A1,Ac1} = Mf(A, Ac),
+    {E11,Ac2} = modify_anno1(E1, Ac1, Mf),
+    {E21,Ac3} = modify_anno1(E2, Ac2, Mf),
+    {E31,Ac4} = modify_anno1(E3, Ac3, Mf),
+    {E41,Ac5} = modify_anno1(E4, Ac4, Mf),
+    {{Tag,A1,E11,E21,E31,E41},Ac5};
+modify_anno1([H|T], Ac, Mf) ->
+    {H1,Ac1} = modify_anno1(H, Ac, Mf),
+    {T1,Ac2} = modify_anno1(T, Ac1, Mf),
+    {[H1|T1],Ac2};
+modify_anno1([], Ac, _Mf) -> {[],Ac};
+modify_anno1(E, Ac, _Mf) when not is_tuple(E), not is_list(E) -> {E,Ac}.
+
 %% vim: ft=erlang
diff --git a/lib/stdlib/src/stdlib.app.src b/lib/stdlib/src/stdlib.app.src
index a435d683a5..d4d2237b38 100644
--- a/lib/stdlib/src/stdlib.app.src
+++ b/lib/stdlib/src/stdlib.app.src
@@ -2,7 +2,7 @@
 %% 
 %% %CopyrightBegin%
 %%
-%% Copyright Ericsson AB 1996-2011. All Rights Reserved.
+%% Copyright Ericsson AB 1996-2015. All Rights Reserved.
 %%
 %% The contents of this file are subject to the Erlang Public License,
 %% Version 1.1, (the "License"); you may not use this file except in
@@ -39,6 +39,7 @@
 	     edlin_expand,
 	     epp,
 	     eval_bits,
+             erl_anno,
 	     erl_bits,
 	     erl_compile,
 	     erl_eval,
diff --git a/lib/stdlib/test/erl_anno_SUITE.erl b/lib/stdlib/test/erl_anno_SUITE.erl
new file mode 100644
index 0000000000..7632fbd324
--- /dev/null
+++ b/lib/stdlib/test/erl_anno_SUITE.erl
@@ -0,0 +1,569 @@
+%%
+%% %CopyrightBegin%
+%%
+%% Copyright Ericsson AB 2001-2015. All Rights Reserved.
+%%
+%% The contents of this file are subject to the Erlang Public License,
+%% Version 1.1, (the "License"); you may not use this file except in
+%% compliance with the License. You should have received a copy of the
+%% Erlang Public License along with this software. If not, it can be
+%% retrieved online at http://www.erlang.org/.
+%%
+%% Software distributed under the License is distributed on an "AS IS"
+%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
+%% the License for the specific language governing rights and limitations
+%% under the License.
+%%
+%% %CopyrightEnd%
+%%
+-module(erl_anno_SUITE).
+
+%-define(debug, true).
+
+-ifdef(debug).
+-include_lib("test_server/include/test_server.hrl").
+-define(format(S, A), io:format(S, A)).
+-else.
+-include_lib("test_server/include/test_server.hrl").
+-define(format(S, A), ok).
+-endif.
+
+-export([all/0, suite/0, groups/0, init_per_suite/1, end_per_suite/1,
+         init_per_group/2, end_per_group/2,
+         init_per_testcase/2, end_per_testcase/2]).
+
+-export([new/1, is_anno/1, generated/1, end_location/1, file/1,
+         line/1, location/1, record/1, text/1, bad/1, neg_line/1]).
+
+-export([parse_abstract/1, mapfold_anno/1]).
+
+all() ->
+    [{group, anno}, {group, parse}].
+
+groups() ->
+    [{anno, [], [new, is_anno, generated, end_location, file,
+                 line, location, record, text, bad, neg_line]},
+     {parse, [], [parse_abstract, mapfold_anno]}].
+
+suite() -> [{ct_hooks,[ts_install_cth]}].
+
+init_per_suite(Config) ->
+    Config.
+
+end_per_suite(_Config) ->
+    ok.
+
+init_per_group(_GroupName, Config) ->
+    Config.
+
+end_per_group(_GroupName, Config) ->
+    Config.
+
+init_per_testcase(_Case, Config) ->
+    Dog=?t:timetrap(?t:minutes(1)),
+    [{watchdog, Dog}|Config].
+
+end_per_testcase(_Case, _Config) ->
+    Dog=?config(watchdog, _Config),
+    test_server:timetrap_cancel(Dog),
+    ok.
+
+-define(INFO(T, V), {T, V}).
+
+-dialyzer({no_fail_call, new/1}).
+new(doc) ->
+    ["Test erl_anno:new/1"];
+new(_Config) ->
+    {'EXIT', {badarg, _}} =
+        (catch erl_anno:new([{location,1},{text, "text"}])), % badarg
+    ok.
+
+is_anno(doc) ->
+    ["Test erl_anno:is_anno/1"];
+is_anno(_Config) ->
+    false = erl_anno:is_anno(a),
+    false = erl_anno:is_anno({a}),
+    false = erl_anno:is_anno([]),
+    false = erl_anno:is_anno([{location, 1}|{generated, true}]),
+    false = erl_anno:is_anno([{generated,false}]),
+    false = erl_anno:is_anno([{generated,true}]),
+    false = erl_anno:is_anno([{location,1},{file,nofile}]),
+    false = erl_anno:is_anno([{location,1},{text,notext}]),
+    false = erl_anno:is_anno([{location,1},{text,[a,b,c]}]),
+
+    true = erl_anno:is_anno(erl_anno:new(1)),
+    A0 = erl_anno:new({1, 17}),
+    true = erl_anno:is_anno(A0),
+    A1 = erl_anno:set_generated(true, A0),
+    true = erl_anno:is_anno(A1),
+    A2 = erl_anno:set_file("", A1),
+    true = erl_anno:is_anno(A2),
+    A3 = erl_anno:set_record(true, A2),
+    true = erl_anno:is_anno(A3),
+    A4 = erl_anno:set_text("text", A3),
+    true = erl_anno:is_anno(A4),
+    A5 = erl_anno:set_file(<<"filename">>, A4),
+    true = erl_anno:is_anno(A5),
+    ok.
+
+generated(doc) ->
+    ["Test 'generated'"];
+generated(_Config) ->
+    test(1, [{generated, true}, {generated, false}]),
+    test(1, [{generated, false}, {generated, true}, {generated, false}]),
+    test({1, 17}, [{generated, false},
+                   {generated, true},
+                   {generated, false}]),
+    test({1, 17}, [{text, "text", [{end_location, {1, 21}}, {length, 4}]},
+                   {generated, false},
+                   {generated, true},
+                   {generated, false}]),
+    test(1, [{generated, false},
+             {generated, true},
+             {generated, false}]),
+    test(1, [{text, "text", [{end_location, 1}, {length, 4}]},
+             {generated, false},
+             {generated, true},
+             {generated, false}]),
+    ok.
+
+end_location(doc) ->
+    ["Test 'end_location'"];
+end_location(_Config) ->
+    test({1, 17}, [{text, "TEXT", [{end_location, {1, 21}}, {length, 4}]},
+                   {text, "TEXT\n", [{end_location, {2, 1}}, {length, 5}]},
+                   {text, "TEXT\ntxt", [{end_location, {2, 4}}, {length, 8}]}]),
+    test(1, [{text, "TEXT", [{end_location, 1}, {length, 4}]},
+             {text, "TEXT\n", [{end_location, 2}, {length, 5}]},
+             {text, "TEXT\ntxt", [{end_location, 2}, {length, 8}]}]),
+    ok.
+
+file(doc) ->
+    ["Test 'file'"];
+file(_Config) ->
+    test(1, [{file, "name"}, {file, ""}]),
+    test({1, 17}, [{file, "name"}, {file, ""}]),
+    ok.
+
+line(doc) ->
+    ["Test 'line'"];
+line(_Config) ->
+    test(1, [{line, 17, [{location, 17}]},
+             {location, {9, 8}, [{line, 9}, {column, 8}]},
+             {line, 14, [{location, {14, 8}}]}]),
+    ok.
+
+location(doc) ->
+    ["Test 'location'"];
+location(_Config) ->
+    test(1, [{location, 2, [{line,2}]},
+             {location, {1, 17}, [{line, 1}, {column, 17}]},
+             {location, {9, 6}, [{line, 9}, {column, 6}]},
+             {location, 9, [{column, undefined}]}]),
+    test(1, [{generated, true},
+             {location, 2, [{line,2}]},
+             {location, {1, 17}, [{line, 1}, {column, 17}]},
+             {location, {9, 6}, [{line, 9}, {column, 6}]},
+             {location, 9, [{column, undefined}]}]),
+    test(1, [{record, true},
+             {location, 2, [{line,2}]},
+             {location, {1, 17}, [{line, 1}, {column, 17}]},
+             {location, {9, 6}, [{line, 9}, {column, 6}]},
+             {location, 9, [{column, undefined}]}]),
+    ok.
+
+record(doc) ->
+    ["Test 'record'"];
+record(_Config) ->
+    test({1, 17}, [{record, true}, {record, false}]),
+    test(1, [{record, true}, {record, false}]),
+    test({1, 17}, [{generated, false},
+                   {generated, true},
+                   {generated, false}]),
+    test({1, 17}, [{text, "text", [{end_location, {1, 21}}, {length, 4}]},
+                   {generated, false},
+                   {generated, true},
+                   {generated, false}]),
+    test(1, [{generated, false},
+             {generated, true},
+             {generated, false}]),
+    test(1, [{text, "text", [{end_location, 1}, {length, 4}]},
+             {generated, false},
+             {generated, true},
+             {generated, false}]),
+    ok.
+
+text(doc) ->
+    ["Test 'text'"];
+text(_Config) ->
+    test(1, [{text, "text", [{end_location, 1}, {length, 4}]},
+             {text, "", [{end_location, 1}, {length, 0}]}]),
+    test({1, 17}, [{text, "text", [{end_location, {1,21}}, {length, 4}]},
+                   {text, "", [{end_location, {1,17}}, {length, 0}]}]),
+    ok.
+
+-dialyzer({[no_opaque, no_fail_call], bad/1}).
+bad(doc) ->
+    ["Test bad annotations"];
+bad(_Config) ->
+    Line = erl_anno:new(1),
+    LineColumn = erl_anno:new({1, 17}),
+    {'EXIT', {badarg, _}} =
+        (catch erl_anno:set_generated(true, bad)), % 3rd arg not opaque
+    {'EXIT', {badarg, _}} =
+        (catch erl_anno:set_generated(false, bad)), % 3rd arg not opaque
+    {'EXIT', {badarg, _}} =
+        (catch erl_anno:set_generated(19, Line)),
+    {'EXIT', {badarg, _}} =
+        (catch erl_anno:set_generated(19, LineColumn)),
+
+    {'EXIT', {badarg, _}} =
+        (catch erl_anno:generated(bad)), % 1st arg not opaque
+    {'EXIT', {badarg, _}} =
+        (catch erl_anno:end_location(bad)), % 1st arg not opaque
+    {'EXIT', {badarg, _}} =
+        (catch erl_anno:file(bad)), % 1st arg not opaque
+    {'EXIT', {badarg, _}} =
+        (catch erl_anno:text(bad)), % 1st arg not opaque
+    {'EXIT', {badarg, _}} =
+        (catch erl_anno:record(bad)), % 1st arg not opaque
+    ok.
+
+neg_line(doc) ->
+    ["Test negative line numbers (OTP 18)"];
+neg_line(_Config) ->
+    neg_line1(false),
+    neg_line1(true),
+    ok.
+
+neg_line1(TextToo) ->
+    Minus8_0 = erl_anno:new(-8),
+    Plus8_0 = erl_anno:new(8),
+    Minus8C_0 = erl_anno:new({-8, 17}),
+    Plus8C_0 = erl_anno:new({8, 17}),
+
+    [Minus8, Plus8, Minus8C, Plus8C] =
+        [case TextToo of
+             true ->
+                 erl_anno:set_text("foo", A);
+             false ->
+                 A
+         end || A <- [Minus8_0, Plus8_0, Minus8C_0, Plus8C_0]],
+
+    tst(-3, erl_anno:set_location(3, Minus8)),
+    tst(-3, erl_anno:set_location(-3, Plus8)),
+    tst(-3, erl_anno:set_location(-3, Minus8)),
+    tst({-3,9}, erl_anno:set_location({3, 9}, Minus8)),
+    tst({-3,9}, erl_anno:set_location({-3, 9}, Plus8)),
+    tst({-3,9}, erl_anno:set_location({-3, 9}, Minus8)),
+    tst(-3, erl_anno:set_location(3, Minus8C)),
+    tst(-3, erl_anno:set_location(-3, Plus8C)),
+    tst(-3, erl_anno:set_location(-3, Minus8C)),
+    tst({-3,9}, erl_anno:set_location({3, 9}, Minus8C)),
+    tst({-3,9}, erl_anno:set_location({-3, 9}, Plus8C)),
+    tst({-3,9}, erl_anno:set_location({-3, 9}, Minus8C)),
+
+    tst(-8, erl_anno:set_generated(true, Plus8)),
+    tst(-8, erl_anno:set_generated(true, Minus8)),
+    tst({-8,17}, erl_anno:set_generated(true, Plus8C)),
+    tst({-8,17}, erl_anno:set_generated(true, Minus8C)),
+    tst(8, erl_anno:set_generated(false, Plus8)),
+    tst(8, erl_anno:set_generated(false, Minus8)),
+    tst({8,17}, erl_anno:set_generated(false, Plus8C)),
+    tst({8,17}, erl_anno:set_generated(false, Minus8C)),
+
+    tst(-3, erl_anno:set_line(3, Minus8)),
+    tst(-3, erl_anno:set_line(-3, Plus8)),
+    tst(-3, erl_anno:set_line(-3, Minus8)),
+    tst({-3,17}, erl_anno:set_line(3, Minus8C)),
+    tst({-3,17}, erl_anno:set_line(-3, Plus8C)),
+    tst({-3,17}, erl_anno:set_line(-3, Minus8C)),
+    ok.
+
+tst(Term, Anno) ->
+    ?format("Term: ~p\n", [Term]),
+    ?format("Anno: ~p\n", [Anno]),
+    case anno_to_term(Anno) of
+        Term ->
+            ok;
+        Else ->
+            case lists:keyfind(location, 1, Else) of
+                {location, Term} ->
+                    ok;
+                _Else2 ->
+                    ?format("Else2 ~p\n", [_Else2]),
+                    io:format("expected ~p\n got     ~p\n", [Term, Else]),
+                    exit({Term, Else})
+            end
+    end.
+
+parse_abstract(doc) ->
+    ["Test erl_parse:new_anno/1, erl_parse:anno_to_term/1"
+     ", and erl_parse:anno_from_term/1"];
+parse_abstract(_Config) ->
+    T = sample_term(),
+    A = erl_parse:abstract(T, [{line,17}]),
+    T1 = erl_parse:anno_to_term(A),
+    Abstr = erl_parse:new_anno(T1),
+    T = erl_parse:normalise(Abstr),
+    Abstr2 = erl_parse:anno_from_term(T1),
+    T = erl_parse:normalise(Abstr2),
+    ok.
+
+mapfold_anno(doc) ->
+    ["Test erl_parse:{map_anno/2,fold_anno/3, and mapfold_anno/3}"];
+mapfold_anno(_Config) ->
+    T = sample_term(),
+    Abstr = erl_parse:abstract(T),
+    CF = fun(Anno, {L, D}) ->
+                 {erl_anno:new(L), {L+1, dict:store(L, Anno, D)}}
+         end,
+    {U, {N, D}} = erl_parse:mapfold_anno(CF, {1, dict:new()}, Abstr),
+    SeqA = erl_parse:fold_anno(fun(Anno, Acc) -> [Anno|Acc] end, [], U),
+    Seq = [erl_anno:location(A) || A <- SeqA],
+    Seq = lists:seq(N-1, 1, -1),
+    NF = fun(Anno) ->
+                 L = erl_anno:location(Anno),
+                 dict:fetch(L, D)
+         end,
+    Abstr = erl_parse:map_anno(NF, U),
+    ok.
+
+sample_term() ->
+    %% This is just a sample.
+    {3,a,4.0,"foo",<<"bar">>,#{a => <<19:64/unsigned-little>>},
+     [1000,2000]}.
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+test(StartLocation, Updates) ->
+    S0 = init(StartLocation),
+    A0 = erl_anno:new(StartLocation),
+    chk(S0, A0, []),
+    eval(Updates, S0, A0).
+
+eval([], _S0, _A0) ->
+    ok;
+eval([{Item, Value}|Updates], S0, A0) ->
+    {S, A} = set(Item, Value, A0, S0, []),
+    eval(Updates, S, A);
+eval([{Item, Value, Secondary}|Updates], S0, A0) ->
+    {S, A} = set(Item, Value, A0, S0, Secondary),
+    eval(Updates, S, A).
+
+init({Line, Column}) ->
+    lists:sort([{location, {Line, Column}} | default()]);
+init(Line) when is_integer(Line) ->
+    lists:sort([{location, Line} | default()]).
+
+set(Item, Value, Anno0, State0, Secondary) ->
+    true = lists:member(Item, primary_items()),
+    ?format("Set '~w' to ~p\n", [Item, Value]),
+    State = set_value(Item, Value, State0),
+    Anno = anno_set(Item, Value, Anno0),
+    ?format("State0 ~p\n", [State0]),
+    ?format("State  ~p\n", [State]),
+    ?format("Anno0  ~p\n", [anno_to_term(Anno0)]),
+    ?format("Anno   ~p\n", [anno_to_term(Anno)]),
+    chk(State, Anno, Secondary),
+    ok = frame(Anno0, Anno, Secondary),
+    {State, Anno}.
+
+frame(OldAnno, NewAnno, Secondary) ->
+    SecItems = [I || {I, _} <- Secondary],
+    Frame = secondary_items() -- (SecItems ++ primary_items()),
+    ?format("Frame items ~p\n", [Frame]),
+    frame1(Frame, OldAnno, NewAnno).
+
+frame1([], _OldAnno, _NewAnno) ->
+    ok;
+frame1([Item|Items], OldAnno, NewAnno) ->
+    V1 = anno_info(OldAnno, Item),
+    V2 = anno_info(NewAnno, Item),
+    ok = check_value(Item, V1, V2),
+    frame1(Items, OldAnno, NewAnno).
+
+chk(State, Anno, Secondary) ->
+    ok = check_simple(Anno),
+    ok = chk_primary(State, Anno),
+    ok = check_secondary(Secondary, State, Anno).
+
+chk_primary(State, Anno) ->
+    chk_primary(primary_items(), State, Anno).
+
+chk_primary([], _State, _Anno) ->
+    ok;
+chk_primary([Item | Items], State, Anno) ->
+    V1 = primary_value(Item, State),
+    V2 = anno_info(Anno, Item),
+    ok = check_value(Item, V1, V2),
+    chk_primary(Items, State, Anno).
+
+check_secondary([], _State, _Anno) ->
+    ok;
+check_secondary([{Item, _}=V1 | Secondary], State, Anno) ->
+    V2 = anno_info(Anno, Item),
+    case {V1, V2} of
+        {{Item, undefined}, undefined} ->
+            ok;
+        _ ->
+            ok = check_value(Item, V1, V2)
+    end,
+    check_secondary(Secondary, State, Anno).
+
+check_value(Item, V1, V2) ->
+    ?format("~w: V1 ~p\n", [Item, V1]),
+    ?format("~w: V2 ~p\n", [Item, V2]),
+    case V1 =:= V2 of
+        true ->
+            ok;
+        false ->
+            io:format("~w: expected ~p\n got     ~p\n", [Item, V1, V2]),
+            exit({V1, V2})
+    end.
+
+check_simple(Anno) ->
+    Term = anno_to_term(Anno),
+    case find_defaults(Term) of
+        [] ->
+            ok;
+        Ds ->
+            io:format("found default values ~w in ~p\n", [Ds, Anno]),
+            exit({defaults, Anno})
+    end,
+    case check_simple1(Term) of
+        true ->
+            ok;
+        false ->
+            io:format("not simple ~p\n", [Anno]),
+            exit({not_simple, Anno})
+    end.
+
+check_simple1(L) when is_integer(L) ->
+    true;
+check_simple1({L, C}) when is_integer(L), is_integer(C) ->
+    true;
+check_simple1(List) ->
+    case lists:sort(List) of
+        [{location, _}] ->
+            false;
+        _ ->
+            true
+    end.
+
+find_defaults(L) when is_list(L) ->
+    [I ||
+        I <- default_items(),
+        {I1, Value} <- L,
+        I =:= I1,
+        Value =:= default_value(I)];
+find_defaults(_) ->
+    [].
+
+anno_to_term(Anno) ->
+    T = erl_anno:to_term(Anno),
+    maybe_sort(T).
+
+maybe_sort(L) when is_list(L) ->
+    lists:sort(L);
+maybe_sort(T) ->
+    T.
+
+anno_set(file, Value, Anno) ->
+    erl_anno:set_file(Value, Anno);
+anno_set(generated, Value, Anno) ->
+    erl_anno:set_generated(Value, Anno);
+anno_set(line, Value, Anno) ->
+    erl_anno:set_line(Value, Anno);
+anno_set(location, Value, Anno) ->
+    erl_anno:set_location(Value, Anno);
+anno_set(record, Value, Anno) ->
+    erl_anno:set_record(Value, Anno);
+anno_set(text, Value, Anno) ->
+    erl_anno:set_text(Value, Anno).
+
+anno_info(Anno, Item) ->
+    Value =
+        case Item of
+            column ->
+                erl_anno:column(Anno);
+            generated ->
+                erl_anno:generated(Anno);
+            end_location ->
+                erl_anno:end_location(Anno);
+            file ->
+                erl_anno:file(Anno);
+            length ->
+                case erl_anno:text(Anno) of
+                    undefined ->
+                        undefined;
+                    Text ->
+                        length(Text)
+                end;
+            line ->
+                erl_anno:line(Anno);
+            location ->
+                erl_anno:location(Anno);
+            record ->
+                erl_anno:record(Anno);
+            text ->
+                erl_anno:text(Anno);
+            _ ->
+                erlang:error(badarg, [Anno, Item])
+        end,
+    if
+        Value =:= undefined ->
+            undefined;
+        true ->
+            {Item, Value}
+    end.
+
+%%% Originally 'location' was primary while 'line' and 'column' were
+%%% secondary (their values are determined by 'location'). But since
+%%% set_line() is used kind of frequently, 'line' is also primary,
+%%% and 'location' secondary (depends on 'line'). 'line' need to be
+%%% handled separately.
+
+set_value(line, Line, State) ->
+    {location, Location} = primary_value(location, State),
+    NewLocation = case Location of
+                      {_, Column} ->
+                          {Line, Column};
+                      _ ->
+                          Line
+                  end,
+    set_value(location, NewLocation, State);
+set_value(Item, Value, State) ->
+    lists:ukeymerge(1, [{Item, Value}], State).
+
+primary_value(line, State) ->
+    {location, Location} = primary_value(location, State),
+    {line, case Location of
+               {Line, _} ->
+                   Line;
+               Line ->
+                   Line
+           end};
+primary_value(Item, State) ->
+    case lists:keyfind(Item, 1, State) of
+        false ->
+            undefined;
+        Tuple ->
+            Tuple
+    end.
+
+default() ->
+    [{Tag, default_value(Tag)} || Tag <- default_items()].
+
+primary_items() ->
+    [file, generated, line, location, record, text].
+
+secondary_items() ->
+    %% 'length' has not been implemented
+    [column, end_location, length, line, location].
+
+default_items() ->
+    [generated, record].
+
+default_value(generated) -> false;
+default_value(record) -> false.