Merge branch 'mc/dialyzer-doc' into dev

* mc/dialyzer-doc:
  dialyzer: Update documentation

5 files changed, 231 insertions, 127 deletions

diff --git a/lib/dialyzer/RELEASE_NOTES b/lib/dialyzer/RELEASE_NOTES
index 08f274a996..3fd5e9cc7d 100644
--- a/lib/dialyzer/RELEASE_NOTES
+++ b/lib/dialyzer/RELEASE_NOTES
@@ -3,8 +3,13 @@
 		(in reversed chronological order)
 ==============================================================================
 
-Version 2.x.x (in Erlang/OTP R14B01)
+Version 2.4.0 (in Erlang/OTP R14B01)
 ------------------------------------
+ - Added ability to supply multiple PLTs for the analysis (option --plts).
+   Currently these PLTs must be independent (i.e., no module appears in more
+   than one PLT) and there must not include files with module name clashes.
+ - Strengthened and streamlined hard-coded type information for some BIFs
+   and key library functions.
  - Fixed pretty rare infinite loop when refining the types of an SCC whose
    functions all returned none() (thanks to Stavros Aronis).
  - Fixed pretty rare crash when taking the infimum of two tuple_sets.
diff --git a/lib/dialyzer/doc/manual.txt b/lib/dialyzer/doc/manual.txt
index d9cb52f722..cc6f9130c7 100644
--- a/lib/dialyzer/doc/manual.txt
+++ b/lib/dialyzer/doc/manual.txt
@@ -123,9 +123,9 @@ The exit status of the command line version is:
 
 
 Usage: dialyzer [--help] [--version] [--shell] [--quiet] [--verbose]
-		[-pa dir]* [--plt plt] [--plts plts] [-Ddefine]*
+		[-pa dir]* [--plt plt] [--plts plt*] [-Ddefine]*
                 [-I include_dir]* [--output_plt file] [-Wwarn]*
-                [--src]  [--gui | --wx] [files_or_dirs] [-r dirs]
+                [--src] [--gui | --wx] [files_or_dirs] [-r dirs]
                 [--apps applications] [-o outfile]
 		[--build_plt] [--add_to_plt] [--remove_from_plt]
 		[--check_plt] [--no_check_plt] [--plt_info] [--get_warnings]
@@ -135,63 +135,75 @@ Options:
    files_or_dirs (for backwards compatibility also as: -c files_or_dirs)
        Use Dialyzer from the command line to detect defects in the
        specified files or directories containing .erl or .beam files,
-       depending on the type of the analysis
+       depending on the type of the analysis.
    -r dirs
        Same as the previous but the specified directories are searched
        recursively for subdirectories containing .erl or .beam files in
-       them, depending on the type of analysis
+       them, depending on the type of analysis.
    --apps applications
-       Option typically used when building or modifying PLT as in:
+       Option typically used when building or modifying a plt as in:
          dialyzer --build_plt --apps erts kernel stdlib mnesia ...
        to conveniently refer to library applications corresponding to the
        Erlang/OTP installation. However, the option is general and can also
        be used during analysis in order to refer to Erlang/OTP applications.
        In addition, file or directory names can also be included, as in:
          dialyzer --apps inets ssl ./ebin ../other_lib/ebin/my_module.beam
+   -o outfile (or --output outfile)
+       When using Dialyzer from the command line, send the analysis
+       results to the specified outfile rather than to stdout.
    --raw
        When using Dialyzer from the command line, output the raw analysis
        results (Erlang terms) instead of the formatted result.
        The raw format is easier to post-process (for instance, to filter
-       warnings or to output HTML pages)
+       warnings or to output HTML pages).
    --src
-       Override the default, which is to analyze BEAM bytecode, and
-       analyze starting from Erlang source code instead
+       Override the default, which is to analyze BEAM files, and
+       analyze starting from Erlang source code instead.
    -Dname (or -Dname=value)
-       When analyzing from source, pass the define to Dialyzer (**)
+       When analyzing from source, pass the define to Dialyzer. (**)
    -I include_dir
-       When analyzing from source, pass the include_dir to Dialyzer (**)
+       When analyzing from source, pass the include_dir to Dialyzer. (**)
    -pa dir
        Include dir in the path for Erlang (useful when analyzing files
-       that have '-include_lib()' directives)
+       that have '-include_lib()' directives).
    --output_plt file
-       Store the plt at the specified file after building it
+       Store the plt at the specified file after building it.
    --plt plt
        Use the specified plt as the initial plt (if the plt was built 
-       during setup the files will be checked for consistency)
-   --plts plts
-       Merges the specified plts to create the initial plt -- requires
-       that the plts are disjoint (i.e., do not have any module
-       appearing in more than one plt)
+       during setup the files will be checked for consistency).
+   --plts plt*
+      Merge the specified plts to create the initial plt -- requires
+      that the plts are disjoint (i.e., do not have any module
+      appearing in more than one plt).
+      The plts are created in the usual way:
+        dialyzer --build_plt --output_plt plt_1 files_to_include
+        ...
+        dialyzer --build_plt --output_plt plt_n files_to_include
+      and then can be used in either of the following ways:
+        dialyzer files_to_analyze --plts plt_1 ... plt_n
+      or:
+        dialyzer --plts plt_1 ... plt_n -- files_to_analyze
+      (Note the -- delimiter in the second case)
    -Wwarn
        A family of options which selectively turn on/off warnings
-       (for help on the names of warnings use dialyzer -Whelp)
+       (for help on the names of warnings use dialyzer -Whelp).
    --shell
-       Do not disable the Erlang shell while running the GUI
+       Do not disable the Erlang shell while running the GUI.
    --version (or -v)
-       Prints the Dialyzer version and some more information and exits
+       Print the Dialyzer version and some more information and exit.
    --help (or -h)
-       Prints this message and exits
+       Print this message and exit.
    --quiet (or -q)
-       Makes Dialyzer a bit more quiet
+       Make Dialyzer a bit more quiet.
    --verbose
-       Makes Dialyzer a bit more verbose
+       Make Dialyzer a bit more verbose.
    --build_plt
        The analysis starts from an empty plt and creates a new one from the
        files specified with -c and -r. Only works for beam files.
        Use --plt or --output_plt to override the default plt location.
    --add_to_plt
        The plt is extended to also include the files specified with -c and -r.
-       Use --plt to specify wich plt to start from, and --output_plt to 
+       Use --plt to specify which plt to start from, and --output_plt to
        specify where to put the plt. Note that the analysis might include 
        files from the plt if they depend on the new files. 
        This option only works with beam files.
@@ -200,23 +212,23 @@ Options:
        from the plt. Note that this may cause a re-analysis of the remaining
        dependent files.
    --check_plt
-       Checks the plt for consistency and rebuilds it if it is not up-to-date.
+       Check the plt for consistency and rebuild it if it is not up-to-date.
    --no_check_plt
        Skip the plt check when running Dialyzer. Useful when working with
        installed plts that never change.
    --plt_info
-       Makes Dialyzer print information about the plt and then quit. The plt 
-       can be specified with --plt.
+       Make Dialyzer print information about the plt and then quit. The plt
+       can be specified with --plt(s).
    --get_warnings
-       Makes Dialyzer emit warnings even when manipulating the plt. Only 
-       emits warnings for files that are actually analyzed.
+       Make Dialyzer emit warnings even when manipulating the plt. Warnings
+       are only emitted for files that are actually analyzed.
    --dump_callgraph file
        Dump the call graph into the specified file whose format is determined
        by the file name extension. Supported extensions are: raw, dot, and ps.
        If something else is used as file name extension, default format '.raw'
        will be used.
    --no_native (or -nn)
-       Bypass the native code compilation of some key files that dialyzer
+       Bypass the native code compilation of some key files that Dialyzer
        heuristically performs when dialyzing many files; this avoids the
        compilation time but it may result in (much) longer analysis time.
    --gui
@@ -236,12 +248,17 @@ Warning options:
      Suppress warnings for unused functions.
   -Wno_improper_lists
      Suppress warnings for construction of improper lists.
+  -Wno_tuple_as_fun
+     Suppress warnings for using tuples instead of funs.
   -Wno_fun_app
      Suppress warnings for fun applications that will fail.
   -Wno_match
      Suppress warnings for patterns that are unused or cannot match.
+  -Wno_opaque
+     Suppress warnings for violations of opaqueness of data types.
   -Wunmatched_returns ***
-     Include warnings for function calls which ignore the return value(s).
+     Include warnings for function calls which ignore a structured return
+     value or do not match against one of many possible return value(s).
   -Werror_handling ***
      Include warnings for functions that only return by means of an exception.
   -Wrace_conditions ***
@@ -262,7 +279,7 @@ The following options are also available but their use is not recommended:
      Warn when the -spec is different than the success typing.
 
 Note:
-   *** These are options that turn on warnings rather than turning them off.
+   *** Identifies options that turn on warnings rather than turning them off.
 
 
 -----------------------------------------------
diff --git a/lib/dialyzer/doc/src/dialyzer.xml b/lib/dialyzer/doc/src/dialyzer.xml
index 29308885fd..01a7e478bc 100644
--- a/lib/dialyzer/doc/src/dialyzer.xml
+++ b/lib/dialyzer/doc/src/dialyzer.xml
@@ -64,81 +64,144 @@
     ]]></code>
     <p>Usage:</p>
     <code type="none"><![CDATA[
-   dialyzer [--help] [--version] [--shell] [--quiet] [--verbose]
-		[-pa dir]* [--plt plt] [-Ddefine]* [-I include_dir]* 
-		[--output_plt file] [-Wwarn]* [--src] 
-		[-c applications] [-r applications] [-o outfile]
+       dialyzer [--help] [--version] [--shell] [--quiet] [--verbose]
+		[-pa dir]* [--plt plt] [--plts plt*] [-Ddefine]*
+                [-I include_dir]* [--output_plt file] [-Wwarn]*
+                [--src] [--gui | --wx] [files_or_dirs] [-r dirs]
+                [--apps applications] [-o outfile]
 		[--build_plt] [--add_to_plt] [--remove_from_plt]
 		[--check_plt] [--no_check_plt] [--plt_info] [--get_warnings]
+                [--no_native]
     ]]></code>
     <p>Options:</p>
     <taglist>
-      <tag><c><![CDATA[-c applications]]></c>(or <c><![CDATA[--command-line applications]]></c>)</tag>
-      <item>use Dialyzer from the command line (no GUI) to detect defects in the
-       specified applications (directories or <c><![CDATA[.erl]]></c> or <c><![CDATA[.beam]]></c> files)</item>
-      <tag><c><![CDATA[-r applications]]></c></tag>
-      <item>same as <c><![CDATA[-c]]></c> only that directories are searched recursively for 
-       subdirectories containing <c><![CDATA[.erl]]></c> or <c><![CDATA[.beam]]></c> files (depending on the 
-       type of analysis)</item>
-      <tag><c><![CDATA[-o outfile]]></c>(or <c><![CDATA[--output outfile]]></c>)</tag>
-      <item>when using Dialyzer from the command line, send the analysis
-       results in the specified <c><![CDATA[outfile]]></c> rather than in stdout</item>
-      <tag><c><![CDATA[--src]]></c></tag>
-      <item>override the default, which is to analyze debug compiled BEAM 
-       bytecode, and analyze starting from Erlang source code instead</item>
+      <tag><c><![CDATA[files_or_dirs]]></c> (for backwards compatibility also
+        as: <c><![CDATA[-c files_or_dirs]]></c></tag>
+      <item>Use Dialyzer from the command line to detect defects in the
+        specified files or directories containing <c><![CDATA[.erl]]></c> or
+         <c><![CDATA[.beam]]></c> files, depending on the type of the
+         analysis.</item>
+      <tag><c><![CDATA[-r dirs]]></c></tag>
+      <item>Same as the previous but the specified directories are searched
+        recursively for subdirectories containing <c><![CDATA[.erl]]></c> or
+        <c><![CDATA[.beam]]></c> files in them, depending on the type of
+        analysis.</item>
+      <tag><c><![CDATA[--apps applications]]></c></tag>
+      <item>Option typically used when building or modifying a plt as in:
+        <code type="none"><![CDATA[
+           dialyzer --build_plt --apps erts kernel stdlib mnesia ...
+        ]]></code>
+        to conveniently refer to library applications corresponding to the
+        Erlang/OTP installation. However, the option is general and can also
+        be used during analysis in order to refer to Erlang/OTP applications.
+        In addition, file or directory names can also be included, as in:
+        <code type="none"><![CDATA[
+           dialyzer --apps inets ssl ./ebin ../other_lib/ebin/my_module.beam
+        ]]></code></item>
+      <tag><c><![CDATA[-o outfile]]></c> (or
+        <c><![CDATA[--output outfile]]></c>)</tag>
+      <item>When using Dialyzer from the command line, send the analysis
+        results to the specified outfile rather than to stdout.</item>
       <tag><c><![CDATA[--raw]]></c></tag>
       <item>When using Dialyzer from the command line, output the raw analysis
-       results (Erlang terms) instead of the formatted result.
-       The raw format is easier to post-process (for instance, to filter
-       warnings or to output HTML pages).</item>
-      <tag><c><![CDATA[-Dname]]></c>(or <c><![CDATA[-Dname=value]]></c>)</tag>
-      <item>when analyzing from source, pass the define to Dialyzer (**)</item>
+        results (Erlang terms) instead of the formatted result. The raw format
+        is easier to post-process (for instance, to filter warnings or to
+        output HTML pages).</item>
+      <tag><c><![CDATA[--src]]></c></tag>
+      <item>Override the default, which is to analyze BEAM files, and
+        analyze starting from Erlang source code instead.</item>
+      <tag><c><![CDATA[-Dname]]></c> (or <c><![CDATA[-Dname=value]]></c>)</tag>
+      <item>When analyzing from source, pass the define to Dialyzer. (**)</item>
       <tag><c><![CDATA[-I include_dir]]></c></tag>
-      <item>when analyzing from source, pass the <c><![CDATA[include_dir]]></c> to Dialyzer (**)</item>
+      <item>When analyzing from source, pass the <c><![CDATA[include_dir]]></c>
+        to Dialyzer. (**)</item>
       <tag><c><![CDATA[-pa dir]]></c></tag>
-      <item>Include <c><![CDATA[dir]]></c> in the path for Erlang. Useful when analyzing files
-       that have <c><![CDATA[-include_lib()]]></c> directives.</item>
+      <item>Include <c><![CDATA[dir]]></c> in the path for Erlang (useful when
+        analyzing files that have <c><![CDATA['-include_lib()']]></c>
+        directives).</item>
       <tag><c><![CDATA[--output_plt file]]></c></tag>
-      <item>Store the PLT at the specified location after building it.</item>
+      <item>Store the plt at the specified file after building it.</item>
       <tag><c><![CDATA[--plt plt]]></c></tag>
-      <item>Use the specified PLT as the initial persistent lookup table.</item>
+      <item>Use the specified plt as the initial plt (if the plt was built
+        during setup the files will be checked for consistency).</item>
+      <tag><c><![CDATA[--plts plt*]]></c></tag>
+      <item>Merge the specified plts to create the initial plt -- requires
+        that the plts are disjoint (i.e., do not have any module
+        appearing in more than one plt).
+        The plts are created in the usual way:
+        <code type="none"><![CDATA[
+           dialyzer --build_plt --output_plt plt_1 files_to_include
+           ...
+           dialyzer --build_plt --output_plt plt_n files_to_include
+        ]]></code>
+        and then can be used in either of the following ways:
+        <code type="none"><![CDATA[
+           dialyzer files_to_analyze --plts plt_1 ... plt_n
+        ]]></code>
+        or:
+        <code type="none"><![CDATA[
+           dialyzer --plts plt_1 ... plt_n -- files_to_analyze
+        ]]></code>
+        (Note the -- delimiter in the second case)</item>
       <tag><c><![CDATA[-Wwarn]]></c></tag>
-      <item>a family of options which selectively turn on/off warnings.
-       (for help on the names of warnings use <c><![CDATA[dialyzer -Whelp]]></c>)</item>
+      <item>A family of options which selectively turn on/off warnings
+        (for help on the names of warnings use
+        <c><![CDATA[dialyzer -Whelp]]></c>).</item>
       <tag><c><![CDATA[--shell]]></c></tag>
-      <item>do not disable the Erlang shell while running the GUI</item>
-      <tag><c><![CDATA[--version (or -v)]]></c></tag>
-      <item>prints the Dialyzer version and some more information and exits</item>
-      <tag><c><![CDATA[--help (or -h)]]></c></tag>
-      <item>prints this message and exits</item>
-      <tag><c><![CDATA[--quiet (or -q)]]></c></tag>
-      <item>makes Dialyzer a bit more quiet</item>
+      <item>Do not disable the Erlang shell while running the GUI.</item>
+      <tag><c><![CDATA[--version]]></c> (or <c><![CDATA[-v]]></c>)</tag>
+      <item>Print the Dialyzer version and some more information and
+        exit.</item>
+      <tag><c><![CDATA[--help]]></c> (or <c><![CDATA[-h]]></c>)</tag>
+      <item>Print this message and exit.</item>
+      <tag><c><![CDATA[--quiet]]></c> (or <c><![CDATA[-q]]></c>)</tag>
+      <item>Make Dialyzer a bit more quiet.</item>
       <tag><c><![CDATA[--verbose]]></c></tag>
-      <item>makes Dialyzer a bit more verbose</item>
-      <tag><c><![CDATA[--check_plt]]></c></tag>
-      <item>Only checks if the initial PLT is up to date and rebuilds it if this is not the case</item>
-      <tag><c><![CDATA[--no_check_plt (or -n)]]></c></tag>
-      <item>Skip the PLT integrity check when running Dialyzer.
-       Useful when working with installed PLTs that never change.</item>
+      <item>Make Dialyzer a bit more verbose.</item>
       <tag><c><![CDATA[--build_plt]]></c></tag>
-      <item>The analysis starts from an empty PLT and creates a new one from
-       the files specified with -c and -r. Only works for beam files.
-       Use --plt or --output_plt to override the default PLT location.</item>
-      <tag><c><![CDATA[--add_to_plt]]></c></tag>   
-      <item> The PLT is extended to also include the files specified with 
-       -c and -r. Use --plt to specify which PLT to start from, and --output_plt 
-       to specify where to put the PLT. Note that the analysis might include 
-       files from the PLT if they depend on the new files. 
-       This option only works with beam files.</item>
+      <item>The analysis starts from an empty plt and creates a new one from
+        the files specified with <c><![CDATA[-c]]></c> and
+        <c><![CDATA[-r]]></c>. Only works for beam files. Use
+        <c><![CDATA[--plt]]></c> or <c><![CDATA[--output_plt]]></c> to
+        override the default plt location.</item>
+       <tag><c><![CDATA[--add_to_plt]]></c></tag>
+       <item>The plt is extended to also include the files specified with
+         <c><![CDATA[-c]]></c> and <c><![CDATA[-r]]></c>. Use
+         <c><![CDATA[--plt]]></c> to specify which plt to start from,
+         and <c><![CDATA[--output_plt]]></c> to specify where to put the plt.
+         Note that the analysis might include files from the plt if they depend
+         on the new files. This option only works with beam files.</item>
        <tag><c><![CDATA[--remove_from_plt]]></c></tag>
-       <item>The information from the files specified with -c and -r is removed
-       from the PLT. Note that this may cause a re-analysis of the remaining
-       dependent files.</item>
+       <item>The information from the files specified with
+         <c><![CDATA[-c]]></c> and <c><![CDATA[-r]]></c> is removed
+         from the plt. Note that this may cause a re-analysis of the remaining
+         dependent files.</item>
+       <tag><c><![CDATA[--check_plt]]></c></tag>
+       <item>Check the plt for consistency and rebuild it if it is not
+         up-to-date.</item>
+       <tag><c><![CDATA[--no_check_plt]]></c></tag>
+       <item>Skip the plt check when running Dialyzer. Useful when working with
+         installed plts that never change.</item>
+       <tag><c><![CDATA[--plt_info]]></c></tag>
+       <item>Make Dialyzer print information about the plt and then quit. The
+         plt can be specified with <c><![CDATA[--plt(s)]]></c>.</item>
        <tag><c><![CDATA[--get_warnings]]></c></tag>
-       <item>Makes Dialyzer emit warnings even when manipulating the PLT. Only 
-       emits warnings for files that are actually analyzed. The default is to
-       not emit any warnings when manipulating the PLT. This option has no 
-       effect when performing a normal analysis.</item>
+       <item>Make Dialyzer emit warnings even when manipulating the plt.
+         Warnings are only emitted for files that are actually analyzed.</item>
+       <tag><c><![CDATA[--dump_callgraph file]]></c></tag>
+       <item>Dump the call graph into the specified file whose format is
+         determined by the file name extension. Supported extensions are: raw,
+         dot, and ps. If something else is used as file name extension, default
+         format '.raw' will be used.</item>
+       <tag><c><![CDATA[--no_native]]></c> (or <c><![CDATA[-nn]]></c>)</tag>
+       <item>Bypass the native code compilation of some key files that Dialyzer
+         heuristically performs when dialyzing many files; this avoids the
+         compilation time but it may result in (much) longer analysis
+         time.</item>
+       <tag><c><![CDATA[--gui]]></c></tag>
+       <item>Use the gs-based GUI.</item>
+       <tag><c><![CDATA[--wx]]></c></tag>
+       <item>Use the wx-based GUI..</item>
     </taglist>
     <note>
       <p>* denotes that multiple occurrences of these options are possible.</p>
@@ -148,11 +211,14 @@
     <p>Warning options:</p>
     <taglist>
       <tag><c><![CDATA[-Wno_return]]></c></tag>
-      <item>Suppress warnings for functions of no return.</item>
+      <item>Suppress warnings for functions that will never return a
+        value.</item>
       <tag><c><![CDATA[-Wno_unused]]></c></tag>
       <item>Suppress warnings for unused functions.</item>
       <tag><c><![CDATA[-Wno_improper_lists]]></c></tag>
       <item>Suppress warnings for construction of improper lists.</item>
+      <tag><c><![CDATA[-Wno_tuple_as_fun]]></c></tag>
+      <item>Suppress warnings for using tuples instead of funs.</item>
       <tag><c><![CDATA[-Wno_fun_app]]></c></tag>
       <item>Suppress warnings for fun applications that will fail.</item>
       <tag><c><![CDATA[-Wno_match]]></c></tag>
@@ -160,6 +226,10 @@
        match.</item>
       <tag><c><![CDATA[-Wno_opaque]]></c></tag>
       <item>Suppress warnings for violations of opaqueness of data types.</item>
+      <tag><c><![CDATA[-Wunmatched_returns]]></c>***</tag>
+      <item>Include warnings for function calls which ignore a structured return
+        value or do not match against one of many possible return
+        value(s).</item>
       <tag><c><![CDATA[-Werror_handling]]></c>***</tag>
       <item>Include warnings for functions that only return by means of an
        exception.</item>
@@ -168,20 +238,22 @@
       <tag><c><![CDATA[-Wbehaviours]]></c>***</tag>
       <item>Include warnings about behaviour callbacks which drift from the
        published recommended interfaces.</item>
-      <tag><c><![CDATA[-Wunmatched_returns]]></c>***</tag>
-      <item>Include warnings for function calls which ignore a structured return
-       value or do not match against one of many possible return value(s).</item>
       <tag><c><![CDATA[-Wunderspecs]]></c>***</tag>
       <item>Warn about underspecified functions 
-      (the -spec is strictly more allowing than the success typing)</item>
+      (the -spec is strictly more allowing than the success typing).</item>
+    </taglist>
+    <p>The following options are also available but their use is not
+      recommended: (they are mostly for Dialyzer developers and internal
+      debugging)</p>
+    <taglist>
       <tag><c><![CDATA[-Woverspecs]]></c>***</tag>
       <item>Warn about overspecified functions 
-      (the -spec is strictly less allowing than the success typing)</item>
+      (the -spec is strictly less allowing than the success typing).</item>
       <tag><c><![CDATA[-Wspecdiffs]]></c>***</tag>
-      <item>Warn when the -spec is different than the success typing</item>
+      <item>Warn when the -spec is different than the success typing.</item>
     </taglist>
     <note>
-      <p>*** These are options that turn on warnings rather than
+      <p>*** Identifies options that turn on warnings rather than
       turning them off.</p>
     </note>
   </section>
@@ -210,6 +282,7 @@ Option   : {files,          [Filename : string()]}
          | {defines,        [{Macro: atom(), Value : term()}]}
          | {from,           src_code | byte_code} %% Defaults to byte_code
          | {init_plt,       FileName : string()}  %% If changed from default
+         | {plts,           [FileName :: string()]} %% If changed from default
          | {include_dirs,   [DirName : string()]} 
          | {output_file,    FileName : string()}
          | {output_plt,     FileName :: string()}
diff --git a/lib/dialyzer/src/dialyzer_cl_parse.erl b/lib/dialyzer/src/dialyzer_cl_parse.erl
index 2f9e577544..5ca7599b35 100644
--- a/lib/dialyzer/src/dialyzer_cl_parse.erl
+++ b/lib/dialyzer/src/dialyzer_cl_parse.erl
@@ -329,7 +329,7 @@ help_warnings() ->
 
 help_message() ->
   S = "Usage: dialyzer [--help] [--version] [--shell] [--quiet] [--verbose]
-		[-pa dir]* [--plt plt] [--plts plts] [-Ddefine]*
+		[-pa dir]* [--plt plt] [--plts plt*] [-Ddefine]*
                 [-I include_dir]* [--output_plt file] [-Wwarn]*
                 [--src] [--gui | --wx] [files_or_dirs] [-r dirs]
                 [--apps applications] [-o outfile]
@@ -340,13 +340,13 @@ Options:
   files_or_dirs (for backwards compatibility also as: -c files_or_dirs)
       Use Dialyzer from the command line to detect defects in the
       specified files or directories containing .erl or .beam files,
-      depending on the type of the analysis
+      depending on the type of the analysis.
   -r dirs
       Same as the previous but the specified directories are searched
       recursively for subdirectories containing .erl or .beam files in
-      them, depending on the type of analysis
+      them, depending on the type of analysis.
   --apps applications
-      Option typically used when building or modifying a PLT as in:
+      Option typically used when building or modifying a plt as in:
         dialyzer --build_plt --apps erts kernel stdlib mnesia ...
       to conveniently refer to library applications corresponding to the
       Erlang/OTP installation. However, the option is general and can also
@@ -355,51 +355,60 @@ Options:
         dialyzer --apps inets ssl ./ebin ../other_lib/ebin/my_module.beam
   -o outfile (or --output outfile)
       When using Dialyzer from the command line, send the analysis
-      results to the specified \"outfile\" rather than to stdout
+      results to the specified outfile rather than to stdout.
   --raw
       When using Dialyzer from the command line, output the raw analysis
       results (Erlang terms) instead of the formatted result.
       The raw format is easier to post-process (for instance, to filter
-      warnings or to output HTML pages)
+      warnings or to output HTML pages).
   --src
       Override the default, which is to analyze BEAM files, and
-      analyze starting from Erlang source code instead
+      analyze starting from Erlang source code instead.
   -Dname (or -Dname=value)
-      When analyzing from source, pass the define to Dialyzer (**)
+      When analyzing from source, pass the define to Dialyzer. (**)
   -I include_dir
-      When analyzing from source, pass the include_dir to Dialyzer (**)
+      When analyzing from source, pass the include_dir to Dialyzer. (**)
   -pa dir
       Include dir in the path for Erlang (useful when analyzing files
-      that have '-include_lib()' directives)
+      that have '-include_lib()' directives).
   --output_plt file
-      Store the plt at the specified file after building it
+      Store the plt at the specified file after building it.
   --plt plt
       Use the specified plt as the initial plt (if the plt was built 
-      during setup the files will be checked for consistency)
-  --plts plts
-      Merges the specified plts to create the initial plt -- requires
+      during setup the files will be checked for consistency).
+  --plts plt*
+      Merge the specified plts to create the initial plt -- requires
       that the plts are disjoint (i.e., do not have any module
-      appearing in more than one plt)
+      appearing in more than one plt).
+      The plts are created in the usual way:
+        dialyzer --build_plt --output_plt plt_1 files_to_include
+        ...
+        dialyzer --build_plt --output_plt plt_n files_to_include
+      and then can be used in either of the following ways:
+        dialyzer files_to_analyze --plts plt_1 ... plt_n
+      or:
+        dialyzer --plts plt_1 ... plt_n -- files_to_analyze
+      (Note the -- delimiter in the second case)
   -Wwarn
       A family of options which selectively turn on/off warnings
-      (for help on the names of warnings use dialyzer -Whelp)
+      (for help on the names of warnings use dialyzer -Whelp).
   --shell
-      Do not disable the Erlang shell while running the GUI
+      Do not disable the Erlang shell while running the GUI.
   --version (or -v)
-      Prints the Dialyzer version and some more information and exits
+      Print the Dialyzer version and some more information and exit.
   --help (or -h)
-      Prints this message and exits
+      Print this message and exit.
   --quiet (or -q)
-      Makes Dialyzer a bit more quiet
+      Make Dialyzer a bit more quiet.
   --verbose
-      Makes Dialyzer a bit more verbose
+      Make Dialyzer a bit more verbose.
   --build_plt
       The analysis starts from an empty plt and creates a new one from the
       files specified with -c and -r. Only works for beam files.
       Use --plt(s) or --output_plt to override the default plt location.
   --add_to_plt
       The plt is extended to also include the files specified with -c and -r.
-      Use --plt(s) to specify wich plt to start from, and --output_plt to
+      Use --plt(s) to specify which plt to start from, and --output_plt to
       specify where to put the plt. Note that the analysis might include
       files from the plt if they depend on the new files.
       This option only works with beam files.
@@ -408,24 +417,24 @@ Options:
       from the plt. Note that this may cause a re-analysis of the remaining
       dependent files.
   --check_plt
-      Checks the plt for consistency and rebuilds it if it is not up-to-date.
+      Check the plt for consistency and rebuild it if it is not up-to-date.
       Actually, this option is of rare use as it is on by default.
   --no_check_plt (or -n)
       Skip the plt check when running Dialyzer. Useful when working with
       installed plts that never change.
   --plt_info
-      Makes Dialyzer print information about the plt and then quit. The plt
+      Make Dialyzer print information about the plt and then quit. The plt
       can be specified with --plt(s).
   --get_warnings
-      Makes Dialyzer emit warnings even when manipulating the plt. Only 
-      emits warnings for files that are actually analyzed.
+      Make Dialyzer emit warnings even when manipulating the plt. Warnings
+      are only emitted for files that are actually analyzed.
   --dump_callgraph file
       Dump the call graph into the specified file whose format is determined
       by the file name extension. Supported extensions are: raw, dot, and ps.
       If something else is used as file name extension, default format '.raw'
       will be used.
   --no_native (or -nn)
-      Bypass the native code compilation of some key files that dialyzer
+      Bypass the native code compilation of some key files that Dialyzer
       heuristically performs when dialyzing many files; this avoids the
       compilation time but it may result in (much) longer analysis time.
   --gui
diff --git a/lib/dialyzer/vsn.mk b/lib/dialyzer/vsn.mk
index d3574e0a71..b2902e95ed 100644
--- a/lib/dialyzer/vsn.mk
+++ b/lib/dialyzer/vsn.mk
@@ -1 +1 @@
-DIALYZER_VSN = 2.3.1
+DIALYZER_VSN = 2.4.0