Patch for PR 10728

[Chris Moller <cmoller@redhat.com>]

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The attached stuff is a patch for PR 10728: 
http://sourceware.org/bugzilla/show_bug.cgi?id=10728 "infinite loop 
evaluating pointer difference w/o complete debug info"

The bug was in valarith.c : value_ptrdiff--if the type structs showed 
size == 0, things came unstuck.  This patch fixes that by issuing a 
warning and assuming size = 1.

The patch includes testcase source files and and an expects file.

The gdb.sum diff between the unpatched and patched make check is also 
attached.

Chris Moller,
Red Hat

[-- Attachment #2: pr10728.patch --]
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Index: gdb/ChangeLog
===================================================================
RCS file: /cvs/src/src/gdb/ChangeLog,v
retrieving revision 1.11289
diff -u -r1.11289 ChangeLog
--- gdb/ChangeLog	25 Jan 2010 19:31:23 -0000	1.11289
+++ gdb/ChangeLog	27 Jan 2010 18:56:27 -0000
@@ -1,3 +1,9 @@
+2010-01-25  Chris Moller  <cmoller@redhat.com>
+
+	PR gdb/10728:
+	* valarith.c (value_ptrdiff): Added a test for a zero type length,
+	warn if found, and assume length = 1.
+
 2010-01-25  Tom Tromey  <tromey@redhat.com>
 
 	PR gdb/11049:
Index: gdb/valarith.c
===================================================================
RCS file: /cvs/src/src/gdb/valarith.c,v
retrieving revision 1.79
diff -u -r1.79 valarith.c
--- gdb/valarith.c	20 Jan 2010 18:06:15 -0000	1.79
+++ gdb/valarith.c	27 Jan 2010 18:56:29 -0000
@@ -122,6 +122,13 @@
 an integer nor a pointer of the same type."));
 
   sz = TYPE_LENGTH (check_typedef (TYPE_TARGET_TYPE (type1)));
+  if (sz == 0) 
+    {
+      warning (_("Type size unknown, assuming 1. "
+               "Try casting to a known type, or void *."));
+      sz = 1;
+    }
+
   return (value_as_long (arg1) - value_as_long (arg2)) / sz;
 }
 
Index: gdb/testsuite/ChangeLog
===================================================================
RCS file: /cvs/src/src/gdb/testsuite/ChangeLog,v
retrieving revision 1.2101
diff -u -r1.2101 ChangeLog
--- gdb/testsuite/ChangeLog	25 Jan 2010 19:31:23 -0000	1.2101
+++ gdb/testsuite/ChangeLog	27 Jan 2010 18:56:45 -0000
@@ -1,3 +1,12 @@
+2010-01-26  Chris Moller  <cmoller@redhat.com>
+
+	PR gdb/10728
+	* gdb.cp/pr10728-x.h: New file.
+	* gdb.cp/pr10728-x.cc: New file.
+	* gdb.cp/pr10728-y.cc: New file.
+	* gdb.cp/pr10728.exp: New file.
+	* gdb.cp/Makefile.in (EXECUTABLES): Add pr10728
+	
 2010-01-25  Tom Tromey  <tromey@redhat.com>
 
 	PR gdb/11049:
Index: gdb/testsuite/gdb.cp/Makefile.in
===================================================================
RCS file: /cvs/src/src/gdb/testsuite/gdb.cp/Makefile.in,v
retrieving revision 1.7
diff -u -r1.7 Makefile.in
--- gdb/testsuite/gdb.cp/Makefile.in	10 Dec 2009 20:57:10 -0000	1.7
+++ gdb/testsuite/gdb.cp/Makefile.in	27 Jan 2010 18:56:45 -0000
@@ -4,7 +4,7 @@
 EXECUTABLES = ambiguous annota2 anon-union cplusfuncs cttiadd \
 	derivation inherit local member-ptr method misc \
         overload ovldbreak ref-typ ref-typ2 templates userdef virtfunc namespace \
-	ref-types ref-params method2 pr9594 gdb2495 virtfunc2
+	ref-types ref-params method2 pr9594 gdb2495 virtfunc2 pr10728
 
 all info install-info dvi install uninstall installcheck check:
 	@echo "Nothing to be done for $@..."
Index: gdb/testsuite/gdb.cp/pr10728-x.cc
===================================================================
RCS file: gdb/testsuite/gdb.cp/pr10728-x.cc
diff -N gdb/testsuite/gdb.cp/pr10728-x.cc
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ gdb/testsuite/gdb.cp/pr10728-x.cc	27 Jan 2010 18:56:45 -0000
@@ -0,0 +1,7 @@
+#include "pr10728-x.h"
+
+int main()
+{
+  X* x = y();
+  return 0;		// marker 1
+}
Index: gdb/testsuite/gdb.cp/pr10728-x.h
===================================================================
RCS file: gdb/testsuite/gdb.cp/pr10728-x.h
diff -N gdb/testsuite/gdb.cp/pr10728-x.h
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ gdb/testsuite/gdb.cp/pr10728-x.h	27 Jan 2010 18:56:45 -0000
@@ -0,0 +1,9 @@
+struct Y;
+struct X
+{
+  Y* y1;
+  Y* y2;
+};
+
+X* y();
+
Index: gdb/testsuite/gdb.cp/pr10728-y.cc
===================================================================
RCS file: gdb/testsuite/gdb.cp/pr10728-y.cc
diff -N gdb/testsuite/gdb.cp/pr10728-y.cc
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ gdb/testsuite/gdb.cp/pr10728-y.cc	27 Jan 2010 18:56:45 -0000
@@ -0,0 +1,11 @@
+#include "pr10728-x.h"
+struct Y{};
+
+X* y()
+{
+  static X xx;
+  static Y yy;
+  xx.y1 = &yy;
+  xx.y2 = xx.y1+1;
+  return &xx;
+}
Index: gdb/testsuite/gdb.cp/pr10728.exp
===================================================================
RCS file: gdb/testsuite/gdb.cp/pr10728.exp
diff -N gdb/testsuite/gdb.cp/pr10728.exp
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ gdb/testsuite/gdb.cp/pr10728.exp	27 Jan 2010 18:56:45 -0000
@@ -0,0 +1,73 @@
+# Copyright 2010 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# This file is part of the gdb testsuite
+
+set nl		"\[\r\n\]+"
+
+if { [skip_cplus_tests] } { continue }
+
+load_lib "cp-support.exp"
+
+set testfile "pr10728"
+set srcfile ${testfile}-x.cc
+set tfx ${testfile}-x
+set tfy ${testfile}-y
+set binfile ${objdir}/${subdir}/${testfile}
+
+if  { [gdb_compile "${srcdir}/${subdir}/${tfy}.cc" "${tfy}.o" object {c++}] != "" } {
+     untested psmang.exp
+     return -1
+}
+
+if  { [gdb_compile "${srcdir}/${subdir}/${tfx}.cc" "${tfx}.o" object {debug c++}] != "" } {
+     untested psmang.exp
+     return -1
+}
+
+if  { [gdb_compile "${tfx}.o ${tfy}.o" ${binfile} executable {debug c++}] != "" } {
+     untested psmang.exp
+     return -1
+}
+
+
+gdb_exit
+gdb_start
+gdb_reinitialize_dir $srcdir/$subdir
+gdb_load ${binfile}
+
+if ![runto_main] then {
+    perror "couldn't run to breakpoint"
+    continue
+}
+
+# set a breakpoint at the return stmt
+
+gdb_breakpoint [gdb_get_line_number "marker 1"]
+gdb_continue_to_breakpoint "marker 1"
+
+send_gdb "print x->y2 - x->y1\n"
+
+gdb_expect {
+  -re "warning: Type size unknown, assuming 1\. Try casting to a known type, or void \*\.\[^=\]*= 1" {
+     pass "print x->y2 - x->y1"
+  }
+  timeout { fail "(timeout) print x->y2 - x->y1" }
+}
+
+gdb_exit
+return 0
+
+

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--- gdb-virgin.sum	2010-01-25 22:03:19.916165023 -0500
+++ gdb-patched2.sum	2010-01-26 22:24:47.539164893 -0500
@@ -1,4 +1,4 @@
-Test Run By moller on Mon Jan 25 21:55:54 2010
+Test Run By moller on Tue Jan 26 22:06:34 2010
 Native configuration is i686-pc-linux-gnu
 
 		=== gdb tests ===
@@ -11460,6 +11460,9 @@
 Running ../../../src/gdb/testsuite/gdb.cp/pr-574.exp ...
 PASS: gdb.cp/pr-574.exp: continue to breakpoint: end of constructors
 PASS: gdb.cp/pr-574.exp: PR gdb/574
+Running ../../../src/gdb/testsuite/gdb.cp/pr10728.exp ...
+PASS: gdb.cp/pr10728.exp: continue to breakpoint: marker 1
+PASS: gdb.cp/pr10728.exp: print x->y2 - x->y1
 Running ../../../src/gdb/testsuite/gdb.cp/pr9631.exp ...
 PASS: gdb.cp/pr9631.exp: continue to breakpoint: after bar tender is initialized
 PASS: gdb.cp/pr9631.exp: print tender
@@ -12530,7 +12533,7 @@
 PASS: gdb.mi/mi-nsmoribund.exp: resume all, thread specific breakpoint
 PASS: gdb.mi/mi-nsmoribund.exp: hit thread specific breakpoint
 PASS: gdb.mi/mi-nsmoribund.exp: thread state: all running except the breakpoint thread
-FAIL: gdb.mi/mi-nsmoribund.exp: unexpected stop
+PASS: gdb.mi/mi-nsmoribund.exp: resume all, program exited normally
 Running ../../../src/gdb/testsuite/gdb.mi/mi-nsthrexec.exp ...
 PASS: gdb.mi/mi-nsthrexec.exp: successfully compiled posix threads test case
 PASS: gdb.mi/mi-nsthrexec.exp: breakpoint at main
@@ -15083,7 +15086,8 @@
 PASS: gdb.threads/local-watch-wrong-thread.exp: local watchpoint still triggers
 PASS: gdb.threads/local-watch-wrong-thread.exp: let thread_function0 return
 PASS: gdb.threads/local-watch-wrong-thread.exp: breakpoint on thread_function0's caller
-PASS: gdb.threads/local-watch-wrong-thread.exp: local watchpoint automatically deleted
+ERROR: Process no longer exists
+UNRESOLVED: gdb.threads/local-watch-wrong-thread.exp: local watchpoint automatically deleted
 Running ../../../src/gdb/testsuite/gdb.threads/manythreads.exp ...
 PASS: gdb.threads/manythreads.exp: successfully compiled posix threads test case
 PASS: gdb.threads/manythreads.exp: set print sevenbit-strings
@@ -15640,11 +15644,11 @@
 
 		=== gdb Summary ===
 
-# of expected passes		14847
-# of unexpected failures	26
+# of expected passes		14849
+# of unexpected failures	25
 # of expected failures		41
 # of untested testcases		3
-# of unresolved testcases	1
+# of unresolved testcases	2
 # of unsupported tests		61
 /home/moller/tinkering/fsfgdb-10728/build/gdb/testsuite/../../gdb/gdb version  7.0.50.20100125-cvs -nw -nx