[binutils-gdb] Fix latent quote char bug in generic_printstr

[Tom Tromey <tromey@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=1be8435c74de6738aec7ed623b59e381fa9bb644

commit 1be8435c74de6738aec7ed623b59e381fa9bb644
Author: Tom Tromey <tom@tromey.com>
Date:   Wed Jan 26 18:07:18 2022 -0700

    Fix latent quote char bug in generic_printstr
    
    generic_printstr prints an empty string like:
    
          fputs_filtered ("\"\"", stream);
    
    However, this seems wrong to me if the quote character is something
    other than double quote.  This patch fixes this latent bug.  Thanks to
    Andrew for the test case.
    
    Co-authored-by: Andrew Burgess <aburgess@redhat.com>

Diff:
---
 gdb/testsuite/gdb.fortran/empty-string.exp | 33 ++++++++++++++++++++++++++++++
 gdb/testsuite/gdb.fortran/empty-string.f90 | 30 +++++++++++++++++++++++++++
 gdb/valprint.c                             |  2 +-
 3 files changed, 64 insertions(+), 1 deletion(-)

diff --git a/gdb/testsuite/gdb.fortran/empty-string.exp b/gdb/testsuite/gdb.fortran/empty-string.exp
new file mode 100644
index 00000000000..892f189784a
--- /dev/null
+++ b/gdb/testsuite/gdb.fortran/empty-string.exp
@@ -0,0 +1,33 @@
+# Copyright 2022 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/> .
+
+# Test printing of an empty Fortran string.
+
+if {[skip_fortran_tests]} { return -1 }
+
+standard_testfile ".f90"
+load_lib fortran.exp
+
+if {[prepare_for_testing "failed to prepare" $testfile $srcfile {debug f90}]} {
+    return -1
+}
+
+if ![fortran_runto_main] {
+    return -1
+}
+
+gdb_breakpoint [gdb_get_line_number "Break here"]
+gdb_continue_to_breakpoint "run to test location"
+gdb_test "print string" " = ''"
diff --git a/gdb/testsuite/gdb.fortran/empty-string.f90 b/gdb/testsuite/gdb.fortran/empty-string.f90
new file mode 100644
index 00000000000..574ed7fb7aa
--- /dev/null
+++ b/gdb/testsuite/gdb.fortran/empty-string.f90
@@ -0,0 +1,30 @@
+! Copyright 2022 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/>.
+
+program empty_string
+  implicit none
+
+  integer :: ret
+
+  ret = string_length('')
+
+contains
+
+  integer(kind=4) function string_length(string)
+    character*(*) :: string
+    string_length = len(string)		! Break here.
+  end function string_length
+
+end program empty_string
diff --git a/gdb/valprint.c b/gdb/valprint.c
index 91a59419c4e..395c6e9dd29 100644
--- a/gdb/valprint.c
+++ b/gdb/valprint.c
@@ -2516,7 +2516,7 @@ generic_printstr (struct ui_file *stream, struct type *type,
 
   if (length == 0)
     {
-      gdb_puts ("\"\"", stream);
+      gdb_printf (stream, "%c%c", quote_char, quote_char);
       return;
     }