Re: [PATCH 2/3] gdb: improve disassembler styling when Pygments raises an exception

[Simon Marchi <simark@simark.ca>]

> +# Check that, if the user is using Python Pygments for disassembler
> +# styling, then the styling correctly switches off when an error is
> +# detected in the Python code.
> +proc test_disassembler_error_handling { } {
> +
> +    # This test requires the Python Pygments module to be installed
> +    # and used by GDB.
> +    if { !$::python_disassembly_styling } {
> +	return
> +    }
> +
> +    save_vars { env(TERM) } {
> +	# We need an ANSI-capable terminal to get the output.
> +	setenv TERM ansi
> +
> +	# Restart GDB with the correct TERM variable setting, this
> +	# means that GDB will enable styling.
> +	clean_restart_and_disable "restart 4" $::binfile
> +
> +	# Disable use of libopcodes for styling.  As this function is
> +	# only called when Python Pygments module is available, we
> +	# should now be using that module to style the disassembler
> +	# output.
> +	gdb_test_no_output "maint set libopcodes-styling enabled off"
> +
> +	# Disassemble a single instruction and ensure that the output
> +	# has styling markers in it.
> +	set insn_before [get_single_disassembled_insn]
> +	gdb_assert { [regexp "\033" $insn_before] } \
> +	    "have style markers when Pygments is working fine"
> +
> +	# Now replace the standard function that colorizes the
> +	# disassembler output, with a new function that always returns
> +	# None, this should cause GDB to stop using the Pygments
> +	# module for disassembler styling.
> +	gdb_py_test_silent_cmd \
> +	    [multi_line_input \
> +		 "python" \
> +		 "def replacement_colorize_disasm(content,gdbarch):" \
> +		 "  return None" \
> +		 "gdb.styling.colorize_disasm = replacement_colorize_disasm" \
> +		 "\004"] \

Any reason you are using \004 here, instead of end?  I don't quite
understand why, but it seems to cause some random failures.  Running the
test under `taskset -c 2` makes it fail most of the time.  Running it
with check-read1 makes it fail consistently:

  FAIL: gdb.base/style.exp: capture_command_output for x/1i *main

When changing \004 for end, it passes.  I don't have an explanation why
though.

Simon