[2/4] Make add-symbol-file's address argument optional

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 27c6ed0a7c..e6e763b506 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -3,6 +3,8 @@ 
 	* symfile.c (symbol_file_command, symbol_file_add_main_1)
 	(_initialize_symfile): Add option "-o" to symbol-file to add an
 	offset to each section of the symbol file.
+	(add_symbol_file_command): Do not require the second argument.  If
+	omitted, load sections at the addresses specified in the file.
 
 2018-06-07  Pedro Alves  <palves@redhat.com>
 
diff --git a/gdb/doc/ChangeLog b/gdb/doc/ChangeLog
index 319d06a25f..7ddf5b0e9d 100644
--- a/gdb/doc/ChangeLog
+++ b/gdb/doc/ChangeLog
@@ -1,6 +1,8 @@ 
 2018-06-08  Petr Tesarik  <ptesarik@suse.com>
 
 	* gdb.texinfo (Files): Document "symbol-file -o offset".
+	(Files): The address argument for "add-symbol-file" is no longer
+	mandatory.
 
 2018-06-05  Tom Tromey	<tom@tromey.com>
 
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 9d1c29612b..b83ce052e7 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -18917,18 +18917,21 @@  the program is running.  To do this, use the @code{kill} command
 
 @kindex add-symbol-file
 @cindex dynamic linking
-@item add-symbol-file @var{filename} @var{address}
-@itemx add-symbol-file @var{filename} @var{address} @r{[} -readnow @r{|} -readnever @r{]}
-@itemx add-symbol-file @var{filename} @var{address} -s @var{section} @var{address} @dots{}
+@item add-symbol-file @var{filename} @r{[} @var{address} @r{]}
+@itemx add-symbol-file @var{filename} @r{[} @var{address} @r{]} @r{[} -readnow @r{|} -readnever @r{]}
+@itemx add-symbol-file @var{filename} @r{[} @var{address} @r{]} -s @var{section} @var{address} @dots{}
 The @code{add-symbol-file} command reads additional symbol table
 information from the file @var{filename}.  You would use this command
 when @var{filename} has been dynamically loaded (by some other means)
 into the program that is running.  The @var{address} should give the memory
-address at which the file has been loaded; @value{GDBN} cannot figure
-this out for itself.  You can additionally specify an arbitrary number
+address at which the file has been loaded.
+You can additionally specify an arbitrary number
 of @samp{-s @var{section} @var{address}} pairs, to give an explicit
 section name and base address for that section.  You can specify any
 @var{address} as an expression.
+If @var{address} is omitted, @value{GDBN} will use the section
+addresses found in @var{filename}.  You can use @samp{-s} to
+override this default and load a section at a different address.
 
 The symbol table of the file @var{filename} is added to the symbol table
 originally read with the @code{symbol-file} command.  You can use the
diff --git a/gdb/symfile.c b/gdb/symfile.c
index 09344f83d2..d319bb0564 100644
--- a/gdb/symfile.c
+++ b/gdb/symfile.c
@@ -2161,29 +2161,26 @@  add_symbol_file_command (const char *args, int from_tty)
 
   validate_readnow_readnever (flags);
 
-  /* This command takes at least two arguments.  The first one is a
-     filename, and the second is the address where this file has been
-     loaded.  Abort now if this address hasn't been provided by the
-     user.  */
-  if (!seen_addr)
-    error (_("The address where %s has been loaded is missing"),
-	   filename.get ());
-
   /* Print the prompt for the query below.  And save the arguments into
      a sect_addr_info structure to be passed around to other
      functions.  We have to split this up into separate print
      statements because hex_string returns a local static
      string.  */
 
-  printf_unfiltered (_("add symbol table from file \"%s\" at\n"),
+  printf_unfiltered (_("add symbol table from file \"%s\""),
 		     filename.get ());
   section_addr_info section_addrs;
-  for (sect_opt &sect : sect_opts)
+  std::vector<sect_opt>::const_iterator it = sect_opts.begin ();
+  if (!seen_addr)
+    ++it;
+  for (; it != sect_opts.end (); ++it)
     {
       CORE_ADDR addr;
-      const char *val = sect.value;
-      const char *sec = sect.name;
+      const char *val = it->value;
+      const char *sec = it->name;
 
+      if (section_addrs.size () == 0)
+	printf_unfiltered (_(" at\n"));
       addr = parse_and_eval_address (val);
 
       /* Here we store the section offsets in the order they were
@@ -2198,6 +2195,8 @@  add_symbol_file_command (const char *args, int from_tty)
 	 At this point, we don't know what file type this is,
 	 so we can't determine what section names are valid.  */
     }
+  if (section_addrs.size () == 0)
+    printf_unfiltered ("\n");
 
   if (from_tty && (!query ("%s", "")))
     error (_("Not confirmed."));
diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index a9e0ec09ff..ffd97e66b9 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,6 +1,8 @@ 
 2018-06-08  Petr Tesarik  <ptesarik@suse.com>
 
 	* gdb.base/relocate.exp: Add test for "symbol-file -o ".
+	Test add-symbol-file behavior when the address argument is
+	omitted.
 
 2018-06-05  Tom Tromey  <tom@tromey.com>
 
diff --git a/gdb/testsuite/gdb.base/relocate.exp b/gdb/testsuite/gdb.base/relocate.exp
index 77f6a88159..a3af8cea61 100644
--- a/gdb/testsuite/gdb.base/relocate.exp
+++ b/gdb/testsuite/gdb.base/relocate.exp
@@ -73,6 +73,21 @@  gdb_test_multiple "add-symbol-file -s .text 0x200 $binfile 0x100" $test {
 	gdb_test "n" "Not confirmed\." $test
     }
 }
+# Check that passing a single "-s .text" is equivallent to passing
+# the text address in a positional argument.
+set test "add-symbol-file -s .text, no address"
+gdb_test_multiple "add-symbol-file $binfile -s .text 0x100" $test {
+    -re "add symbol table from file \"${binfile}\" at\r\n\t\.text_addr = 0x100\r\n\\(y or n\\) " {
+	gdb_test "n" "Not confirmed\." $test
+    }
+}
+# Check section addresses can be omitted.
+set test "add-symbol-file no address"
+gdb_test_multiple "add-symbol-file $binfile" $test {
+    -re "add symbol table from file \"${binfile}\"\r\n\\(y or n\\) " {
+	gdb_test "n" "Not confirmed\." $test
+    }
+}
 # Test that passing "--" disables option processing.
 gdb_test "add-symbol-file -- $binfile 0x100 -s .bss 0x3" \
     "Unrecognized argument \"-s\"" \