errors: indent "symbol redeclaration" context

This is the continuation of the work on the readability of errors
context.

For example, what used to be:
  input.y:5.10-24: %printer redeclaration for <field2>
  input.y:3.11-25: previous declaration

is now:
  input.y:5.10-24: %printer redeclaration for <field2>
  input.y:3.11-25:     previous declaration

* NEWS: Document this change.
* src/symtab.c (symbol_redeclaration, semantic_type_redeclaration,
user_token_number_redeclaration, default_tagged_destructor_set,
default_tagless_destructor_set, default_tagged_printer_set,
default_tagless_printer_set): Use complain_at_indent to
output with increased indentation level.
* tests/input.at: Apply this change.

Signed-off-by: Akim Demaille <akim@lrde.epita.fr>

NEWS

@@ -14,6 +14,18 @@ GNU Bison NEWS
   Incorrect definitions of YY_, issued by yacc.c when no parser header is
   generated, are removed.
 
+** Changes in the format of errors and exceptions output
+
+  This used to be the format of many error reports:
+
+    foo.y:5.10-24: result type clash on merge function 'merge': <t3> != <t2>
+    foo.y:4.13-27: previous declaration
+
+  It is now:
+
+    foo.y:5.10-25: result type clash on merge function 'merge': <t3> != <t2>
+    foo.y:4.13-27:     previous declaration
+
 * Noteworthy changes in release 2.6.2 (2012-08-03) [stable]
 
 ** Bug fixes

src/symtab.c

@@ -150,16 +150,20 @@ static void
 symbol_redeclaration (symbol *s, const char *what, location first,
                       location second)
 {
-  complain_at (second, _("%s redeclaration for %s"), what, s->tag);
+  unsigned i = 0;
-  complain_at (first, _("previous declaration"));
+  complain_at_indent (second, &i, _("%s redeclaration for %s"), what, s->tag);
+  i += SUB_INDENT;
+  complain_at_indent (first, &i, _("previous declaration"));
 }
 
 static void
 semantic_type_redeclaration (semantic_type *s, const char *what, location first,
                              location second)
 {
-  complain_at (second, _("%s redeclaration for <%s>"), what, s->tag);
+  unsigned i = 0;
-  complain_at (first, _("previous declaration"));
+  complain_at_indent (second, &i, _("%s redeclaration for <%s>"), what, s->tag);
+  i += SUB_INDENT;
+  complain_at_indent (first, &i, _("previous declaration"));
 }
 
 
@@ -515,6 +519,7 @@ symbol_pack_processor (void *this, void *null ATTRIBUTE_UNUSED)
 static void
 user_token_number_redeclaration (int num, symbol *first, symbol *second)
 {
+  unsigned i = 0;
   /* User token numbers are not assigned during the parsing, but in a
      second step, via a traversal of the symbol table sorted on tag.
 
@@ -526,10 +531,11 @@ user_token_number_redeclaration (int num, symbol *first, symbol *second)
       first = second;
       second = tmp;
     }
-  complain_at (second->location,
+  complain_at_indent (second->location, &i,
                       _("user token number %d redeclaration for %s"),
                       num, second->tag);
-  complain_at (first->location, _("previous declaration for %s"),
+  complain_at_indent (first->location, &i,
+                      _("previous declaration for %s"),
                       first->tag);
 }
 
@@ -923,9 +929,11 @@ default_tagged_destructor_set (code_props const *destructor)
 {
   if (default_tagged_destructor.code)
     {
-      complain_at (destructor->location,
+      unsigned i = 0;
+      complain_at_indent (destructor->location, &i,
                           _("redeclaration for default tagged %%destructor"));
-      complain_at (default_tagged_destructor.location,
+      i += SUB_INDENT;
+      complain_at_indent (default_tagged_destructor.location, &i,
 		          _("previous declaration"));
     }
   default_tagged_destructor = *destructor;
@@ -936,9 +944,11 @@ default_tagless_destructor_set (code_props const *destructor)
 {
   if (default_tagless_destructor.code)
     {
-      complain_at (destructor->location,
+      unsigned i = 0;
+      complain_at_indent (destructor->location, &i,
                           _("redeclaration for default tagless %%destructor"));
-      complain_at (default_tagless_destructor.location,
+      i += SUB_INDENT;
+      complain_at_indent (default_tagless_destructor.location, &i,
                           _("previous declaration"));
     }
   default_tagless_destructor = *destructor;
@@ -949,9 +959,11 @@ default_tagged_printer_set (code_props const *printer)
 {
   if (default_tagged_printer.code)
     {
-      complain_at (printer->location,
+      unsigned i = 0;
+      complain_at_indent (printer->location, &i,
                           _("redeclaration for default tagged %%printer"));
-      complain_at (default_tagged_printer.location,
+      i += SUB_INDENT;
+      complain_at_indent (default_tagged_printer.location, &i,
 		          _("previous declaration"));
     }
   default_tagged_printer = *printer;
@@ -962,9 +974,11 @@ default_tagless_printer_set (code_props const *printer)
 {
   if (default_tagless_printer.code)
     {
-      complain_at (printer->location,
+      unsigned i = 0;
+      complain_at_indent (printer->location, &i,
                           _("redeclaration for default tagless %%printer"));
-      complain_at (default_tagless_printer.location,
+      i += SUB_INDENT;
+      complain_at_indent (default_tagless_printer.location, &i,
 		          _("previous declaration"));
     }
   default_tagless_printer = *printer;