compiler: Don't create filenames starting with "./"

In the location information tables in the run-time system, source
filenames that are the same as the module name plus ".erl" extension
are not stored explicitly, thus saving memory.

To take advantage of that optimization, avoid complicating the names of
files in the current working directory; specifically, make sure that
"./" is not prepended to the name.

3 files changed, 15 insertions, 3 deletions

diff --git a/lib/compiler/src/compile.erl b/lib/compiler/src/compile.erl
index ce8a5bf864..ee7c87fced 100644
--- a/lib/compiler/src/compile.erl
+++ b/lib/compiler/src/compile.erl
@@ -1426,6 +1426,8 @@ iofile(File) when is_atom(File) ->
 iofile(File) ->
     {filename:dirname(File), filename:basename(File, ".erl")}.
 
+erlfile(".", Base, Suffix) ->
+    Base ++ Suffix;
 erlfile(Dir, Base, Suffix) ->
     filename:join(Dir, Base ++ Suffix).
 
diff --git a/lib/kernel/src/file.erl b/lib/kernel/src/file.erl
index 5e4e1b0ba8..706c60caaf 100644
--- a/lib/kernel/src/file.erl
+++ b/lib/kernel/src/file.erl
@@ -1163,7 +1163,7 @@ path_open_first([Path|Rest], Name, Mode, LastError) ->
 	{error, _} = Error ->
 	    Error;
 	FilePath ->
-	    FileName = filename:join(FilePath, Name),
+	    FileName = fname_join(FilePath, Name),
 	    case open(FileName, Mode) of
 		{ok, Fd} ->
 		    {ok, Fd, FileName};
@@ -1176,6 +1176,11 @@ path_open_first([Path|Rest], Name, Mode, LastError) ->
 path_open_first([], _Name, _Mode, LastError) ->
     {error, LastError}.
 
+fname_join(".", Name) ->
+    Name;
+fname_join(Dir, Name) ->
+    filename:join(Dir, Name).
+
 %%%-----------------------------------------------------------------
 %%% Utility functions.
 
diff --git a/lib/stdlib/src/epp.erl b/lib/stdlib/src/epp.erl
index d804c1dee5..230a4a0612 100644
--- a/lib/stdlib/src/epp.erl
+++ b/lib/stdlib/src/epp.erl
@@ -684,7 +684,7 @@ scan_include_lib([{'(',_Llp},{string,_Lf,NewName0},{')',_Lrp},{dot,_Ld}],
 	{error,_E1} ->
 	    case catch find_lib_dir(NewName) of
 		{LibDir, Rest} when is_list(LibDir) ->
-		    LibName = filename:join([LibDir | Rest]),
+		    LibName = fname_join([LibDir | Rest]),
 		    case file:open(LibName, [read]) of
 			{ok,NewF} ->
 			    ExtraPath = [filename:dirname(LibName)],
@@ -1154,7 +1154,12 @@ expand_var1(NewName) ->
     [[$$ | Var] | Rest] = filename:split(NewName),
     Value = os:getenv(Var),
     true = Value =/= false,
-    {ok, filename:join([Value | Rest])}.
+    {ok, fname_join([Value | Rest])}.
+
+fname_join(["." | [_|_]=Rest]) ->
+    fname_join(Rest);
+fname_join(Components) ->
+    filename:join(Components).
 
 %% The line only. (Other tokens may have the column and text as well...)
 loc_attr(Line) when is_integer(Line) ->