[stdlib] Open error log file as utf8

This allows the use of ~ts/~tp/~tw in calls to error_logger:format/2,
error_logger:error_msg/2 and error_logger:info_msg/2.

3 files changed, 21 insertions, 3 deletions

diff --git a/lib/kernel/doc/src/error_logger.xml b/lib/kernel/doc/src/error_logger.xml
index 27db00819f..91bf57cb91 100644
--- a/lib/kernel/doc/src/error_logger.xml
+++ b/lib/kernel/doc/src/error_logger.xml
@@ -126,6 +126,12 @@ ok</pre>
 	  <seealso marker="#error_report/1"><c>error_report/1</c></seealso>
 	  instead.</p>
         </warning>
+        <warning>
+          <p>If the Unicode translation modifier (<c>t</c>) is used in
+            the format string, all error handlers must ensure that the
+            formatted output is correctly encoded for the I/O
+            device.</p>
+        </warning>
       </desc>
     </func>
     <func>
@@ -197,6 +203,12 @@ ok</pre>
             the standard event handler, meaning no further events are
             logged. When in doubt, use <c>info_report/1</c> instead.</p>
         </warning>
+        <warning>
+          <p>If the Unicode translation modifier (<c>t</c>) is used in
+            the format string, all error handlers must ensure that the
+            formatted output is correctly encoded for the I/O
+            device.</p>
+        </warning>
       </desc>
     </func>
     <func>
@@ -262,7 +274,7 @@ ok</pre>
               successful, or <c>{error, allready_have_logfile}</c> if
               logging to file is already enabled, or an error tuple if
               another error occurred (for example, if <c><anno>Filename</anno></c>
-              cannot be opened).</p>
+              cannot be opened). The file is opened with encoding UTF-8.</p>
           </item>
           <tag><c>close</c></tag>
           <item>
@@ -345,6 +357,12 @@ ok</pre>
             the standard event handler, meaning no further events are
             logged. When in doubt, use <c>warning_report/1</c> instead.</p>
         </warning>
+        <warning>
+          <p>If the Unicode translation modifier (<c>t</c>) is used in
+            the format string, all error handlers must ensure that the
+            formatted output is correctly encoded for the I/O
+            device.</p>
+        </warning>
       </desc>
     </func>
     <func>
diff --git a/lib/kernel/doc/src/kernel_app.xml b/lib/kernel/doc/src/kernel_app.xml
index 75e1e18d86..e5ac031539 100644
--- a/lib/kernel/doc/src/kernel_app.xml
+++ b/lib/kernel/doc/src/kernel_app.xml
@@ -186,7 +186,7 @@
           <tag><c>{file, FileName}</c></tag>
           <item><p>Installs the standard event handler, which prints error
            reports to file <c>FileName</c>, where <c>FileName</c>
-           is a string.</p></item>
+           is a string. The file is opened with encoding UTF-8.</p></item>
           <tag><c>false</c></tag>
           <item>
             <p>No standard event handler is installed, but
diff --git a/lib/stdlib/src/error_logger_file_h.erl b/lib/stdlib/src/error_logger_file_h.erl
index 76f89841b9..b7c193f965 100644
--- a/lib/stdlib/src/error_logger_file_h.erl
+++ b/lib/stdlib/src/error_logger_file_h.erl
@@ -55,7 +55,7 @@ init(File) ->
 
 init(File, PrevHandler) ->
     process_flag(trap_exit, true),
-    case file:open(File, [write]) of
+    case file:open(File, [write,{encoding,utf8}]) of
 	{ok,Fd} ->
             Depth = error_logger:get_format_depth(),
 	    State = #st{fd=Fd,filename=File,prev_handler=PrevHandler,