Improve gendef.pl diagnostic on failure to open sym file

There have been numerous buildfarm failures but the diagnostic is
currently silent about the reason for failure to open the file. Let's
see if we can get to the bottom of it.

Backpatch to all live branches.

diff --git a/src/tools/msvc/gendef.pl b/src/tools/msvc/gendef.pl
index 8ef0422df9d6514ca901ccd8b2ed65839def2580..247cff0cac3e761f0de56217685c3d6d484ba55f 100644 (file)
--- a/src/tools/msvc/gendef.pl
+++ b/src/tools/msvc/gendef.pl
@@ -27,7 +27,7 @@ while (<$ARGV[0]/*.obj>)
        print ".";
        system("dumpbin /symbols /out:symbols.out $_ >NUL")
          && die "Could not call dumpbin";
-       open(F, "<symbols.out") || die "Could not open symbols.out for $_\n";
+       open(F, "<symbols.out") || die "Could not open symbols.out for $_: $!\n";
        while (<F>)
        {
                s/\(\)//g;