mmix bfd: fix bfd_assert for R_MMIX_PUSHJ_STUBBABLE against undef'd symbol

Spotted when inspecting gcc testsuite logs, but this already is
covered by the ld-mmix testsuite, it's just that the assert is ignored
since the regexp match is for a substring and not anchored.

With the anchors added but not the bugfix, the ld.log shows that the
asserts cause a non-match as intended:

Executing on host: sh -c {./ld-new   -LX/src/ld/testsuite/ld-mmix  -m elf64mmix -o tmpdir/dump tmpdir/undef-2.o tmpdir/start.o  2>&1}  /dev/null dump.tmp (timeout = 300)
./ld-new: BFD (GNU Binutils) 2.34.50.20200629 assertion fail X/src/bfd/elf64-mmix.c:2845
./ld-new: BFD (GNU Binutils) 2.34.50.20200629 assertion fail X/src/bfd/elf64-mmix.c:2845
./ld-new: BFD (GNU Binutils) 2.34.50.20200629 assertion fail X/src/bfd/elf64-mmix.c:2845
./ld-new: tmpdir/undef-2.o:(.text+0x0): undefined reference to `undefd'
failed with: <./ld-new: BFD (GNU Binutils) 2.34.50.20200629 assertion fail X/src/bfd/elf64-mmix.c:2845
./ld-new: BFD (GNU Binutils) 2.34.50.20200629 assertion fail X/src/bfd/elf64-mmix.c:2845
./ld-new: BFD (GNU Binutils) 2.34.50.20200629 assertion fail X/src/bfd/elf64-mmix.c:2845
./ld-new: tmpdir/undef-2.o:(.text+0x0): undefined reference to `undefd'>, expected: <\A[^\n\r]*undefined reference to `undefd'\Z>
FAIL: ld-mmix/undef-2

Gone with the fix of course, leaving just the intended "undefined
reference" like.

I'm not going to add anchors manually for all the "error:" strings in
the test-suite, not even in the mmix parts.  Sorry, but I'll just do
it for *these* specific undefined-reference tests.

Just a thought: maybe the run_dump_test "error:" string should
*automatically* get anchor marks prepended and appended for a single
line match as in the patch, "\A[^\n\r]*" prepended and \Z appended
unless either anchor mark or \r or \n is present in the regexp?

Committed.

bfd:
	* elf64-mmix.c (mmix_elf_relax_section): Improve accounting for
	R_MMIX_PUSHJ_STUBBABLE relocs against undefined symbols.

ld/testsuite:
	* testsuite/ld-mmix/undef-1.d, testsuite/ld-mmix/undef-1m.d,
	testsuite/ld-mmix/undef-2.d, testsuite/ld-mmix/undef-2m.d: Add
	start- and end-anchors to error-string to match just a
	single-line error-message.

5 files changed, 11 insertions, 4 deletions

diff --git a/ld/ChangeLog b/ld/ChangeLog
index 98d10c0..b667566 100644
--- a/ld/ChangeLog
+++ b/ld/ChangeLog
@@ -1,3 +1,10 @@
+2020-07-15  Hans-Peter Nilsson  <hp@bitrange.com>
+
+	* testsuite/ld-mmix/undef-1.d, testsuite/ld-mmix/undef-1m.d,
+	testsuite/ld-mmix/undef-2.d, testsuite/ld-mmix/undef-2m.d: Add
+	start- and end-anchors to error-string to match just a
+	single-line error-message.
+
 2020-07-13  Alan Modra  <amodra@gmail.com>
 
 	* testsuite/ld-scripts/default-script1.d: Don't skip, xfail
diff --git a/ld/testsuite/ld-mmix/undef-1.d b/ld/testsuite/ld-mmix/undef-1.d
index fb8c7ee..ad8d757 100644
--- a/ld/testsuite/ld-mmix/undef-1.d
+++ b/ld/testsuite/ld-mmix/undef-1.d
@@ -1,4 +1,4 @@
 #source: undef-1.s
 #source: start.s
 #ld: -m elf64mmix
-#error: undefined reference to `regvar'
+#error: \A[^\n\r]*undefined reference to `regvar'\Z
diff --git a/ld/testsuite/ld-mmix/undef-1m.d b/ld/testsuite/ld-mmix/undef-1m.d
index 001d7f6..e747e50 100644
--- a/ld/testsuite/ld-mmix/undef-1m.d
+++ b/ld/testsuite/ld-mmix/undef-1m.d
@@ -1,4 +1,4 @@
 #source: undef-1.s
 #source: start.s
 #ld: -m mmo
-#error: undefined reference to `regvar'
+#error: \A[^\n\r]*undefined reference to `regvar'\Z
diff --git a/ld/testsuite/ld-mmix/undef-2.d b/ld/testsuite/ld-mmix/undef-2.d
index 52844db..2dc2b4e 100644
--- a/ld/testsuite/ld-mmix/undef-2.d
+++ b/ld/testsuite/ld-mmix/undef-2.d
@@ -2,4 +2,4 @@
 #source: start.s
 #as: -x
 #ld: -m elf64mmix
-#error: undefined reference to `undefd'
+#error: \A[^\n\r]*undefined reference to `undefd'\Z
diff --git a/ld/testsuite/ld-mmix/undef-2m.d b/ld/testsuite/ld-mmix/undef-2m.d
index aa0becc..7eb3c67 100644
--- a/ld/testsuite/ld-mmix/undef-2m.d
+++ b/ld/testsuite/ld-mmix/undef-2m.d
@@ -2,4 +2,4 @@
 #source: start.s
 #as: -x
 #ld: -m mmo
-#error: undefined reference to `undefd'
+#error: \A[^\n\r]*undefined reference to `undefd'\Z