Address #575 by adding a new footnote in TY_(ErrorSummary) suggesting that if

this behavior is not wanted, then which option to use to prevent it.

include/tidyenum.h

@@ -122,27 +122,28 @@ extern "C" {
  ** than the short report.
  */
 #define FOREACH_FOOTNOTE_MSG(FN) \
-/** Explanatory text. */           FN(TEXT_ACCESS_ADVICE1)        \
+    FN(FOOTNOTE_TRIM_EMPTY_ELEMENT) \
-/** Explanatory text. */           FN(TEXT_ACCESS_ADVICE2)        \
+    FN(TEXT_ACCESS_ADVICE1)         \
-/** Explanatory text. */           FN(TEXT_BAD_FORM)              \
+    FN(TEXT_ACCESS_ADVICE2)         \
-/** Explanatory text. */           FN(TEXT_BAD_MAIN)              \
+    FN(TEXT_BAD_FORM)               \
-/** Explanatory text. */           FN(TEXT_HTML_T_ALGORITHM)      \
+    FN(TEXT_BAD_MAIN)               \
-/** Explanatory text. */           FN(TEXT_INVALID_URI)           \
+    FN(TEXT_HTML_T_ALGORITHM)       \
-/** Explanatory text. */           FN(TEXT_INVALID_UTF16)         \
+    FN(TEXT_INVALID_URI)            \
-/** Explanatory text. */           FN(TEXT_INVALID_UTF8)          \
+    FN(TEXT_INVALID_UTF16)          \
-/** Explanatory text. */           FN(TEXT_M_IMAGE_ALT)           \
+    FN(TEXT_INVALID_UTF8)           \
-/** Explanatory text. */           FN(TEXT_M_IMAGE_MAP)           \
+    FN(TEXT_M_IMAGE_ALT)            \
-/** Explanatory text. */           FN(TEXT_M_LINK_ALT)            \
+    FN(TEXT_M_IMAGE_MAP)            \
-/** Explanatory text. */           FN(TEXT_M_SUMMARY)             \
+    FN(TEXT_M_LINK_ALT)             \
-/** Explanatory text. */           FN(TEXT_SGML_CHARS)            \
+    FN(TEXT_M_SUMMARY)              \
-/** Explanatory text. */           FN(TEXT_USING_BODY)            \
+    FN(TEXT_SGML_CHARS)             \
-/** Explanatory text. */           FN(TEXT_USING_FONT)            \
+    FN(TEXT_USING_BODY)             \
-/** Explanatory text. */           FN(TEXT_USING_FRAMES)          \
+    FN(TEXT_USING_FONT)             \
-/** Explanatory text. */           FN(TEXT_USING_LAYER)           \
+    FN(TEXT_USING_FRAMES)           \
-/** Explanatory text. */           FN(TEXT_USING_NOBR)            \
+    FN(TEXT_USING_LAYER)            \
-/** Explanatory text. */           FN(TEXT_USING_SPACER)          \
+    FN(TEXT_USING_NOBR)             \
-/** Explanatory text. */           FN(TEXT_VENDOR_CHARS)          \
+    FN(TEXT_USING_SPACER)           \
-/** Explanatory text. */           FN(TEXT_WINDOWS_CHARS)
+    FN(TEXT_VENDOR_CHARS)           \
+    FN(TEXT_WINDOWS_CHARS)
 
 
 /** These messages are used to generate additional dialogue style output from

localize/translations/tidy.pot

@@ -5,7 +5,7 @@ msgstr ""
 "Plural-Forms: nplurals=2; plural=n != 1;\n"
 "X-Generator: HTML Tidy poconvert.rb\n"
 "Project-Id-Version: \n"
-"POT-Creation-Date: 2017-09-28 13:24:51\n"
+"POT-Creation-Date: 2017-09-29 11:24:53\n"
 "Last-Translator: jderry\n"
 "Language-Team: \n"
 
@@ -1980,6 +1980,15 @@ msgid ""
 "include an alternative layout inside a NOFRAMES element.\n"
 msgstr ""
 
+#. This console output should be limited to 78 characters per line.
+msgctxt "FOOTNOTE_TRIM_EMPTY_ELEMENT"
+msgid ""
+"One or more empty elements were present in the source document but\n"
+"dropped on output. If these elements are necessary or you don't want\n"
+"this behavior, then consider setting the option \"drop-empty-elements\"\n"
+"to no.\n"
+msgstr ""
+
 #. This console output should be limited to 78 characters per line.
 #. - The URL should not be translated unless you find a matching URL in your language.
 msgctxt "TEXT_ACCESS_ADVICE1"

src/language_en.h

@@ -1761,6 +1761,13 @@ static languageDefinition language_en = { whichPluralForm_en, {
         "doesn't support frames. A frames-based page should always\n"
         "include an alternative layout inside a NOFRAMES element.\n"
     },
+    {/* This console output should be limited to 78 characters per line. */
+      FOOTNOTE_TRIM_EMPTY_ELEMENT,  0,
+        "One or more empty elements were present in the source document but\n"
+        "dropped on output. If these elements are necessary or you don't want\n"
+        "this behavior, then consider setting the option \"drop-empty-elements\"\n"
+        "to no.\n"
+    },
     {/* This console output should be limited to 78 characters per line.
         - The URL should not be translated unless you find a matching URL in your language. */
       TEXT_ACCESS_ADVICE1,          0,

src/message.c

@@ -1010,6 +1010,7 @@ static struct _dialogueDispatchTable {
     { STRING_NO_ERRORS,            TidyDialogueSummary  }, /* ReportNumWarnings() */
     { STRING_NOT_ALL_SHOWN,        TidyDialogueSummary  }, /* ReportNumWarnings() */
     
+    { FOOTNOTE_TRIM_EMPTY_ELEMENT, TidyDialogueFootnote },
     { TEXT_ACCESS_ADVICE1,         TidyDialogueFootnote }, /* errorSummary() */
     { TEXT_ACCESS_ADVICE2,         TidyDialogueFootnote },
     { TEXT_BAD_FORM,               TidyDialogueFootnote },
@@ -1030,6 +1031,8 @@ static struct _dialogueDispatchTable {
     { TEXT_USING_NOBR,             TidyDialogueFootnote },
     { TEXT_USING_SPACER,           TidyDialogueFootnote },
     { TEXT_VENDOR_CHARS,           TidyDialogueFootnote },
+    
+    { 0, 0 }
 };
 
 
@@ -1054,6 +1057,7 @@ TidyMessageImpl *formatDialogue( TidyDocImpl* doc, uint code, TidyReportLevel le
                                            doc->warnings, tidyLocalizedStringN( STRING_ERROR_COUNT_WARNING, doc->warnings ),
                                            doc->errors, tidyLocalizedStringN( STRING_ERROR_COUNT_ERROR, doc->errors ) );
 
+        case FOOTNOTE_TRIM_EMPTY_ELEMENT:
         case STRING_HELLO_ACCESS:
         case STRING_NEEDS_INTERVENTION:
         case STRING_NO_ERRORS:
@@ -1222,6 +1226,13 @@ void TY_(ErrorSummary)( TidyDocImpl* doc )
         if (doc->badLayout & USING_BODY)
             TY_(Dialogue)( doc, TEXT_USING_BODY );
     }
+    
+    if (doc->footnotes)
+    {
+        if (doc->footnotes & FN_TRIM_EMPTY_ELEMENT)
+            TY_(Dialogue)( doc, FOOTNOTE_TRIM_EMPTY_ELEMENT );
+    }
+
 }
 
 

src/message.h

@@ -260,6 +260,10 @@ uint TY_(getNextErrorCode)( TidyIterator* iter );
 #define BC_INVALID_URI             32
 #define BC_INVALID_NCR             64
 
+/* other footnote bit field (temporary until formalized) */
+
+#define FN_TRIM_EMPTY_ELEMENT     1
+
 /* Lexer and I/O Macros */
 
 #define REPLACED_CHAR           0

src/parser.c

@@ -337,7 +337,10 @@ Node *TY_(TrimEmptyElement)( TidyDocImpl* doc, Node *element )
     if ( CanPrune(doc, element) )
     {
         if (element->type != TextNode)
+        {
+            doc->footnotes |= FN_TRIM_EMPTY_ELEMENT;
             TY_(Report)(doc, element, NULL, TRIM_EMPTY_ELEMENT);
+        }
         
         return TY_(DiscardElement)(doc, element);
     }

src/tidy-int.h

@@ -76,6 +76,7 @@ struct _TidyDocImpl
     uint                badLayout;   /* for bad style errors */
     uint                badChars;    /* for bad char encodings */
     uint                badForm;     /* bit field, for badly placed form tags, or other format errors */
+    uint                footnotes;   /* bit field, for other footnotes, until formalized */
 
     Bool                HTML5Mode;   /* current mode is html5 */
     Bool                xmlDetected; /* true if XML was used/detected */