dialyzer: Update the PLT properly when a module is changed

Thanks to James Fish for the bug report, and to Stavros Aronis for
fixing the bug.

1 files changed, 61 insertions, 3 deletions

diff --git a/lib/dialyzer/test/plt_SUITE.erl b/lib/dialyzer/test/plt_SUITE.erl
index aee9f449a6..0b8c6dec21 100644
--- a/lib/dialyzer/test/plt_SUITE.erl
+++ b/lib/dialyzer/test/plt_SUITE.erl
@@ -1,17 +1,17 @@
 %% This suite is the only hand made and simply
-%% checks if we can build a plt.
+%% checks if we can build and update a plt.
 
 -module(plt_SUITE).
 
 -include_lib("common_test/include/ct.hrl").
 -include("dialyzer_test_constants.hrl").
 
--export([suite/0, all/0, build_plt/1]).
+-export([suite/0, all/0, build_plt/1, update_plt/1]).
 
 suite() ->
   [{timetrap, ?plt_timeout}].
 
-all() -> [build_plt].
+all() -> [build_plt, update_plt].
 
 build_plt(Config) ->
   OutDir = ?config(priv_dir, Config),
@@ -19,3 +19,61 @@ build_plt(Config) ->
     ok   -> ok;
     fail -> ct:fail(plt_build_fail)
   end.
+
+%%% [James Fish:]
+%%% If a function is removed from a module and the module has previously
+%%% been added to a PLT, the function will not be removed from PLT when
+%%% the PLT is checked. This results in dialyzer failing to produce a
+%%% callgraph warning when doing success typings analysis if the remove
+%%% function is still called in another module
+%%% As the function is not removed from the PLT a prior warning, such as a
+%%% contract types warning, might be emitted when the removed function
+%%% nolonger exists.
+update_plt(Config) ->
+    PrivDir = ?config(priv_dir, Config),
+    Prog1 = <<"-module(plt_gc).
+               -export([one/0]).
+               one() ->
+                  one.">>,
+    {ok, Beam} = compile(Config, Prog1, plt_gc, []),
+
+    ErlangBeam = case code:where_is_file("erlang.beam") of
+                     non_existing ->
+                         filename:join([code:root_dir(),
+                                        "erts", "preloaded", "ebin",
+                                        "erlang.beam"]);
+                     EBeam ->
+                         EBeam
+                 end,
+    Plt = filename:join(PrivDir, "plt_gc.plt"),
+    Opts = [{check_plt, true}, {from, byte_code}],
+    [] = dialyzer:run([{analysis_type, plt_build},
+                       {files, [Beam, ErlangBeam]},
+                       {output_plt, Plt}] ++ Opts),
+
+    Prog2 = <<"-module(plt_gc).
+               -export([two/0]).
+               two() ->
+                  two.">>,
+    {ok, Beam} = compile(Config, Prog2, plt_gc, []),
+
+    Test = <<"-module(test).
+              -export([test/0]).
+              -spec test() -> test.
+              test() ->
+                  plt_gc:one().">>,
+    {ok, TestBeam} = compile(Config, Test, test, []),
+    [{warn_callgraph, _, {call_to_missing, [plt_gc, one, 0]}}] =
+        dialyzer:run([{analysis_type, succ_typings},
+                      {files, [TestBeam]},
+                      {init_plt, Plt}] ++ Opts),
+    ok.
+
+compile(Config, Prog, Module, CompileOpts) ->
+    Source = lists:concat([Module, ".erl"]),
+    PrivDir = ?config(priv_dir,Config),
+    Filename = filename:join([PrivDir, Source]),
+    ok = file:write_file(Filename, Prog),
+    Opts = [{outdir, PrivDir}, debug_info | CompileOpts],
+    {ok, Module} = compile:file(Filename, Opts),
+    {ok, filename:join([PrivDir, lists:concat([Module, ".beam"])])}.