[binutils-gdb] gdb: improved EOF handling when using readline 7

[binutils-gdb] gdb: improved EOF handling when using readline 7

[Andrew Burgess]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=b913bd98ce81a1600463f9a8a30db04d44b64a47

commit b913bd98ce81a1600463f9a8a30db04d44b64a47
Author: Andrew Burgess <aburgess@redhat.com>
Date:   Tue Mar 29 15:07:04 2022 +0100

    gdb: improved EOF handling when using readline 7
    
    In this commit:
    
      commit a6b413d24ccc5d76179bab866834e11fd6fec294
      Date:   Fri Mar 11 14:44:03 2022 +0000
    
          gdb: work around prompt corruption caused by bracketed-paste-mode
    
    a change was made to GDB to work around bug PR gdb/28833.  The
    consequence of this work around is that, when bracketed paste mode is
    enabled in readline, and GDB is quit by sending EOF, then the output
    will look like this:
    
      (gdb)
      quit
    
    The ideal output, which is what we get when bracketed paste mode is
    off, is this:
    
      (gdb) quit
    
    The reason we need to make this change is explained in the original
    commit referenced above.  What isn't mentioned in the above commit, is
    that the change that motivated this work around was only added in
    readline 8, older versions of readline don't require the change.
    
    In later commits in this series I will add a fix to GDB's in-tree copy
    of readline (this fix is back-ported from upstream readline), and then
    I will change GDB so that, when using the (patched) in-tree readline,
    we can have the ideal output in all cases.
    
    However, GDB can be built against the system readline.  When this is
    done, and the system readline is version 8, then we will still have to
    use the work around (two line) style output.
    
    But, if GDB is built against the system readline, and the system
    readline is an older version 7 readline, then there's no reason why we
    can't have the ideal output, after all, readline 7 doesn't include the
    change that we need to work around.
    
    This commit changes GDB so that, when using readline 7 we get the
    ideal output in all cases.  This change is trivial (a simple check
    against the readline version number) so I think this should be fine to
    include.
    
    For testing this commit, you need to configure GDB including the
    '--with-system-readline' flag, and build GDB on a system that uses
    readline 7, for example 'Ubuntu 18.04'.  Then run the test
    'gdb.base/eof-exit.exp', you should expect everything to PASS.
    
    Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=28833

Diff:
---
 gdb/event-top.c                     | 3 ++-
 gdb/testsuite/gdb.base/eof-exit.exp | 2 +-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/gdb/event-top.c b/gdb/event-top.c
index b628f0397cb..6261020b4ac 100644
--- a/gdb/event-top.c
+++ b/gdb/event-top.c
@@ -780,7 +780,8 @@ command_line_handler (gdb::unique_xmalloc_ptr<char> &&rl)
 	 we first print '\n' to move to the next line, and then print the
 	 quit.  This isn't ideal, but avoids corrupting the prompt.  */
       const char *value = rl_variable_value ("enable-bracketed-paste");
-      if (value != nullptr && strcmp (value, "on") == 0)
+      if (value != nullptr && strcmp (value, "on") == 0
+	  && ((rl_readline_version >> 8) & 0xff) > 0x07)
 	printf_unfiltered ("\n");
       printf_unfiltered ("quit\n");
       execute_command ("quit", 1);
diff --git a/gdb/testsuite/gdb.base/eof-exit.exp b/gdb/testsuite/gdb.base/eof-exit.exp
index 2d9530ccebe..ad5f33d2f10 100644
--- a/gdb/testsuite/gdb.base/eof-exit.exp
+++ b/gdb/testsuite/gdb.base/eof-exit.exp
@@ -49,7 +49,7 @@ proc run_test {} {
 	    # line after the 'quit', this catches that case.
 	    fail $gdb_test_name
 	}
-	-re "$::gdb_prompt quit\[^\n\]*\r\n\[^\n\]*$" {
+       -re "$::gdb_prompt \[^\n\r\]*quit\[^\n\]*\r\n\[^\n\]*$" {
 	    pass $gdb_test_name
 	}
 	eof {