[PATCH 2/2] [gdb/testsuite] Fix host_file_normalize_mingw

[Tom de Vries <tdevries@suse.de>]

I ran the testsuite on msys2-ucrt64 with mount point map:
...
  /bin C:/msys64/usr/bin
  /c   C:
  /    C:/msys64
...
and ran into the problem that host_file_normalize didn't translate:
...
/home/user/gdb/build/gdb/testsuite/temp/n/x
...
into:
...
C:/msys64/home/user/gdb/build/gdb/testsuite/temp/n/x
...

Fix this in host_file_normalize_mingw and add a corresponding test in
test-case gdb.testsuite/mount-point-map.exp.

Tested on aarch64-linux and msys2-ucrt64.
---
 gdb/testsuite/gdb.testsuite/mount-point-map.exp | 4 ++++
 gdb/testsuite/lib/gdb.exp                       | 4 ++--
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/gdb/testsuite/gdb.testsuite/mount-point-map.exp b/gdb/testsuite/gdb.testsuite/mount-point-map.exp
index d4c8bfdeff6..cc070622b13 100644
--- a/gdb/testsuite/gdb.testsuite/mount-point-map.exp
+++ b/gdb/testsuite/gdb.testsuite/mount-point-map.exp
@@ -24,3 +24,7 @@ gdb_assert { [host_file_normalize_mingw $d1 $unix_to_win] == $d2 }
 
 set d3 "C:/msys64"
 gdb_assert { [host_file_normalize_mingw $d3 $unix_to_win] == $d3 }
+
+set f1 "/home/user/gdb/build/gdb/testsuite/temp/n/x"
+set f2 "C:/msys64/home/user/gdb/build/gdb/testsuite/temp/n/x"
+gdb_assert { [host_file_normalize_mingw $f1 $unix_to_win] == $f2 }
diff --git a/gdb/testsuite/lib/gdb.exp b/gdb/testsuite/lib/gdb.exp
index b7961eb30dc..4b0249db70b 100644
--- a/gdb/testsuite/lib/gdb.exp
+++ b/gdb/testsuite/lib/gdb.exp
@@ -2381,9 +2381,9 @@ proc host_file_normalize_mingw {filename unix_to_win} {
 	if {[string equal -length $mount_len $unix_filename $filename]} {
 	    if {[string length $filename] == $mount_len} {
 		return "$win_filename/"
-	    } elseif {[string index $filename $mount_len] eq "/"} {
+	    } elseif {[string index $filename [expr $mount_len - 1]] eq "/"} {
 		set rest [string range $filename $mount_len end]
-		return "$win_filename$rest"
+		return "$win_filename/$rest"
 	    }
 	}
     }
-- 
2.43.0