Fix add-symbol-file usage and errors

This patch updates add-symbol-file help and error text.

It changes add-symbol-file to throw an exception if "-s" is seen but
not all of the arguments are given.  Previously this was silently
ignored.

It changes the unrecognized argument message to more clearly state
what went wrong.

Finally, it updates the usage line in the help text to follow GNU
style regarding "metasyntactic variables"; a change I believe should
be made to all gdb help messages.

gdb/ChangeLog
2017-11-29  Tom Tromey  <tom@tromey.com>

	* symfile.c (add_symbol_file_command): Error if some arguments to
	-s are missing.  Change unrecognized-argument error message.
	(_initialize_symfile): Fix usage text for add-symbol-file.

gdb/testsuite/ChangeLog
2017-11-29  Tom Tromey  <tom@tromey.com>

	* gdb.base/relocate.exp: Update invalid argument test.
	Add new tests for invalid arguments.

4 files changed, 31 insertions, 8 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index ebb9699..f3a2175 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,9 @@
+2017-11-29  Tom Tromey  <tom@tromey.com>
+
+	* symfile.c (add_symbol_file_command): Error if some arguments to
+	-s are missing.  Change unrecognized-argument error message.
+	(_initialize_symfile): Fix usage text for add-symbol-file.
+
 2017-11-27  Tom Tromey  <tom@tromey.com>
 
 	* Makefile.in (REMOTE_OBS): Remove.
diff --git a/gdb/symfile.c b/gdb/symfile.c
index feb50f8..c19cdd2 100644
--- a/gdb/symfile.c
+++ b/gdb/symfile.c
@@ -2244,8 +2244,7 @@ add_symbol_file_command (const char *args, int from_tty)
 	      expecting_sec_addr = 1;
 	    }
 	  else
-	    error (_("USAGE: add-symbol-file <filename> <textaddress>"
-		     " [-readnow] [-s <secname> <addr>]*"));
+	    error (_("Unrecognized argument \"%s\""), arg);
 	}
     }
 
@@ -2257,6 +2256,11 @@ add_symbol_file_command (const char *args, int from_tty)
     error (_("The address where %s has been loaded is missing"),
 	   filename.get ());
 
+  if (expecting_sec_name)
+    error (_("Missing section name after \"-s\""));
+  else if (expecting_sec_addr)
+    error (_("Missing section address after \"-s\""));
+
   /* 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
@@ -3882,11 +3886,11 @@ to execute."), &cmdlist);
 
   c = add_cmd ("add-symbol-file", class_files, add_symbol_file_command, _("\
 Load symbols from FILE, assuming FILE has been dynamically loaded.\n\
-Usage: add-symbol-file FILE ADDR [-s <SECT> <SECT_ADDR> -s <SECT> <SECT_ADDR>\
- ...]\nADDR is the starting address of the file's text.\n\
-The optional arguments are section-name section-address pairs and\n\
+Usage: add-symbol-file FILE ADDR [-readnow | -s SECT-NAME SECT-ADDR]...\n\
+ADDR is the starting address of the file's text.\n\
+Each '-s' argument provides a section name and address, and\n\
 should be specified if the data and bss segments are not contiguous\n\
-with the text.  SECT is a section name to be loaded at SECT_ADDR."),
+with the text.  SECT-NAME is a section name to be loaded at SECT-ADDR."),
 	       &cmdlist);
   set_cmd_completer (c, filename_completer);
 
diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 87b917e..4fba24b 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2017-11-29  Tom Tromey  <tom@tromey.com>
+
+	* gdb.base/relocate.exp: Update invalid argument test.
+	Add new tests for invalid arguments.
+
 2017-11-29  Thomas Preud'homme  <thomas.preudhomme@arm.com>
 
 	* gdb.cp/psymtab-parameter.cc (func): Change return type back to long.
diff --git a/gdb/testsuite/gdb.base/relocate.exp b/gdb/testsuite/gdb.base/relocate.exp
index 5639cc8..6eef15f 100644
--- a/gdb/testsuite/gdb.base/relocate.exp
+++ b/gdb/testsuite/gdb.base/relocate.exp
@@ -31,11 +31,19 @@ gdb_reinitialize_dir $srcdir/$subdir
 
 #Check that invalid options are rejected.
 foreach x {"-raednow" "readnow" "foo" "-readnow s"} {
+    set word [lindex $x [expr [llength $x]-1]]
     gdb_test "add-symbol-file ${binfile} 0 $x" \
-	"USAGE: add-symbol-file <filename> <textaddress>.*-readnow.*-s <secname> <addr>.*" \
-	"add-symbol-file: unknown option $x"
+	"Unrecognized argument \"$word\"" \
+	"add-symbol-file: unknown option $word"
 }
 
+gdb_test "add-symbol-file ${binfile} 0 -s" \
+    "Missing section name after .-s." \
+    "add-symbol-file bare -s"
+gdb_test "add-symbol-file ${binfile} 0 -s .whatever" \
+    "Missing section address after .-s." \
+    "add-symbol-file missing address"
+
 # Load the object file.
 gdb_test "add-symbol-file ${binfile} 0" \
 	"Reading symbols from .*${testfile}\\.o\\.\\.\\.done\\.(|\r\nUsing host libthread_db library .*libthread_db.so.*\\.)" \