File 1031-Improve-warnings-for-failing-io-format-cal... of Package erlang

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File 1031-Improve-warnings-for-failing-io-format-calls.patch of Package erlang (Revision 4833d2389f176a3c117df1d7ab7aa8d7)

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From 76aa3246d87bc1a4ea1438e83d3a381ed1af6a68 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= <bjorn@erlang.org>
Date: Fri, 21 May 2021 09:55:12 +0200
Subject: [PATCH] Improve warnings for failing io:format() calls

The following call to `io:format/1`:

t() ->
        io:format("~p\n"),
        ok.

would produce a warning with line number 0:

t.erl:0: Warning: wrong number of arguments in format call

This commit fixes that issue, and while at it also provides more
information than just "wrong number of arguments in format call" for
other failing calls. For example, given the following function:

t(A) ->
        io:format("~p\n"),
        io:format("~p\n", []),
        io:format("~p ~p\n", [A]),
        io:format("\n", [A]),
        ok.

the following warnings will be produced:

t.erl:5:15: Warning: the format string requires an argument list with 1 argument, but no argument list is given
    %    5|     io:format("~p\n"),
    %     |               ^

t.erl:6:23: Warning: the format string requires an argument list with 1 argument, but the argument list is empty
    %    6|     io:format("~p\n", []),
    %     |                       ^

t.erl:7:26: Warning: the format string requires an argument list with 2 arguments, but the argument list contains only 1 argument
    %    7|     io:format("~p ~p\n", [A]),
    %     |                          ^

t.erl:8:21: Warning: the format string requires an empty argument list, but the argument list contains 1 argument
    %    8|     io:format("\n", [A]),
    %     |                     ^
---
 lib/stdlib/src/erl_lint.erl                   | 43 +++++++++++++++----
 lib/stdlib/test/erl_lint_SUITE.erl            |  2 +-
 .../test/erl_lint_SUITE_data/format.erl       |  3 ++
 3 files changed, 38 insertions(+), 10 deletions(-)

diff --git a/lib/stdlib/src/erl_lint.erl b/lib/stdlib/src/erl_lint.erl
index e3bb694629..1d81f3e514 100644
--- a/lib/stdlib/src/erl_lint.erl
+++ b/lib/stdlib/src/erl_lint.erl
@@ -4115,7 +4115,7 @@ is_format_function(M, F) when is_atom(M), is_atom(F) -> false.
 %% check_format_1([Arg]) -> ok | {warn,Level,Format,[Arg]}.
 
 check_format_1([Fmt]) ->
-    check_format_1([Fmt,{nil,0}]);
+    check_format_1([Fmt,no_argument_list]);
 check_format_1([Fmt,As]) ->
     check_format_2(Fmt, canonicalize_string(As));
 check_format_1([_Dev,Fmt,As]) ->
@@ -4128,8 +4128,6 @@ canonicalize_string({string,Anno,Cs}) ->
 canonicalize_string(Term) ->
     Term.
 
-%% check_format_2([Arg]) -> ok | {warn,Level,Format,[Arg]}.
-
 check_format_2(Fmt, As) ->
     case Fmt of
         {string,A,S} ->
@@ -4141,6 +4139,8 @@ check_format_2(Fmt, As) ->
             {warn,2,Anno,"format string not a textual constant",[]}
     end.
 
+check_format_2a(Fmt, FmtAnno, no_argument_list=As) ->
+    check_format_3(Fmt, FmtAnno, As);
 check_format_2a(Fmt, FmtAnno, As) ->
     case args_list(As) of
         true ->
@@ -4153,19 +4153,44 @@ check_format_2a(Fmt, FmtAnno, As) ->
             {warn,2,Anno,"format arguments perhaps not a list",[]}
     end.
 
-%% check_format_3(FormatString, [Arg]) -> ok | {warn,Level,Format,[Arg]}.
-
 check_format_3(Fmt, FmtAnno, As) ->
     case check_format_string(Fmt) of
         {ok,Need} ->
-            case args_length(As) of
-                Len when length(Need) =:= Len -> ok;
-                _Len -> {warn,1,element(2, As),"wrong number of arguments in format call",[]}
-            end;
+            check_format_4(Need, FmtAnno, As);
         {error,S} ->
             {warn,1,FmtAnno,"format string invalid (~ts)",[S]}
     end.
 
+check_format_4([], _FmtAnno, no_argument_list) ->
+    ok;
+check_format_4(Need, FmtAnno, no_argument_list) ->
+    Msg = "the format string requires an argument list with ~s, but no argument list is given",
+    {warn,1,FmtAnno,Msg,[arguments(length(Need))]};
+check_format_4(Need, _FmtAnno, As) ->
+    Anno = element(2, As),
+    Prefix = "the format string requires an argument list with ~s, but the argument list ",
+    case {args_length(As),length(Need)} of
+        {Same,Same} ->
+            ok;
+        {Actual,0} ->
+            Msg = "the format string requires an empty argument list, but the argument list contains ~s",
+            {warn,1,Anno,Msg,[arguments(Actual)]};
+        {0,Needed} ->
+            Msg = Prefix ++ "is empty",
+            {warn,1,Anno,Msg,[arguments(Needed)]};
+        {Actual,Needed} when Actual < Needed ->
+            Msg = Prefix ++ "contains only ~s",
+            {warn,1,Anno,Msg,[arguments(Needed),arguments(Actual)]};
+        {Actual,Needed} when Actual > Needed ->
+            Msg = Prefix ++ "contains ~s",
+            {warn,1,Anno,Msg,[arguments(Needed),arguments(Actual)]}
+    end.
+
+arguments(1) ->
+    "1 argument";
+arguments(N) ->
+    [integer_to_list(N), " arguments"].
+
 args_list({cons,_A,_H,T}) -> args_list(T);
 %% Strange case: user has written something like [a | "bcd"]; pretend
 %% we don't know:
diff --git a/lib/stdlib/test/erl_lint_SUITE.erl b/lib/stdlib/test/erl_lint_SUITE.erl
index 39f4964e06..134d63477a 100644
--- a/lib/stdlib/test/erl_lint_SUITE.erl
+++ b/lib/stdlib/test/erl_lint_SUITE.erl
@@ -3509,7 +3509,7 @@ otp_8051(Config) when is_list(Config) ->
 
 %% Check that format warnings are generated.
 format_warn(Config) when is_list(Config) ->
-    L1 = 14,
+    L1 = 16,
     L2 = 5,
     format_level(1, L1, Config),
     format_level(2, L1+L2, Config),
diff --git a/lib/stdlib/test/erl_lint_SUITE_data/format.erl b/lib/stdlib/test/erl_lint_SUITE_data/format.erl
index 4748f315c6..65af8d9d9b 100644
--- a/lib/stdlib/test/erl_lint_SUITE_data/format.erl
+++ b/lib/stdlib/test/erl_lint_SUITE_data/format.erl
@@ -24,6 +24,8 @@
 %%% There will be warnings at level 2 and 3.
 
 f(F) ->
+    io:format("~p"),                            %1
+
     io:format("~", F),				%2
     io:format("~", [F]),			%1
     io:format(a, b),				%1
@@ -35,6 +37,7 @@ f(F) ->
     io:format("la cucaracha~n"),
     io:format(""),
     io:format("~p ~p~n", [F]),			%1
+    io:format("~p ~p~n", [1,2,F]),		%1
     io:format("~p~n", [F]),
     io:format("~m"),				%1
     io:format(F, "~p", []),			%1
-- 
2.26.2

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File 1031-Improve-warnings-for-failing-io-format-calls.patch of Package erlang (Revision 4833d2389f176a3c117df1d7ab7aa8d7)

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