EOF before first field is only ok for first character in io:fread

2 files changed, 10 insertions, 4 deletions

diff --git a/lib/stdlib/src/io_lib_fread.erl b/lib/stdlib/src/io_lib_fread.erl
index 137759bbab..411d293876 100644
--- a/lib/stdlib/src/io_lib_fread.erl
+++ b/lib/stdlib/src/io_lib_fread.erl
@@ -123,8 +123,8 @@ fread([_F|_Format], [_C|_Line], _N, _Results) ->
     fread_error(input);
 fread([_|_]=Format, [], N, Results) ->
     {more,Format,N,Results};
-fread([_|_], eof, _N, []) ->
-    %% This is at start of format string so no error.
+fread([_|_], eof, 0, []) ->
+    %% This is at start of input so no error.
     eof;
 fread([_|_], eof, _N, _Results) ->
     %% This is an error as there is no more input.
@@ -175,8 +175,8 @@ fread1([$l|Format], _F, Sup, _U, Line, N, Res, _AllFormat) ->
 fread1(_Format, _F, _Sup, _U, [], N, Res, AllFormat) ->
     %% Need more input here.
     {more,[$~|AllFormat],N,Res};
-fread1(_Format, _F, _Sup, _U, eof, _N, [], _AllFormat) ->
-    %% This is at start of format string so no error.
+fread1(_Format, _F, _Sup, _U, eof, 0, [], _AllFormat) ->
+    %% This is at start of input so no error.
     eof;
 fread1(_Format, _F, _Sup, _U, eof, _N, _Res, _AllFormat) ->
     %% This is an error as there is no more input.
diff --git a/lib/stdlib/test/io_SUITE.erl b/lib/stdlib/test/io_SUITE.erl
index 03dc655426..bb02a879c2 100644
--- a/lib/stdlib/test/io_SUITE.erl
+++ b/lib/stdlib/test/io_SUITE.erl
@@ -2011,7 +2011,13 @@ io_lib_fread_literal(Suite) when is_list(Suite) ->
     %%
     ?line {done,eof,_} = io_lib:fread([], eof, "~d"),
     ?line {done,eof,_} = io_lib:fread([], eof, " ~d"),
+    ?line {more,C1} = io_lib:fread([], " \n", " ~d"),
+    ?line {done,{error,{fread,input}},_} = io_lib:fread(C1, eof, " ~d"),
+    ?line {done,{ok,[18]},""} = io_lib:fread(C1, "18\n", " ~d"),
     %%
     ?line {done,eof,_} = io_lib:fread([], eof, "d"),
     ?line {done,eof,_} = io_lib:fread([], eof, " d"),
+    ?line {more,C2} = io_lib:fread([], " \n", " d"),
+    ?line {done,{error,{fread,input}},_} = io_lib:fread(C2, eof, " d"),
+    ?line {done,{ok,[]},[]} = io_lib:fread(C2, "d\n", " d"),
     ok.