[PATCH] [gdb/tdep] Eliminate ostringstream use from arc_check_tdesc_feature

Tom de Vries
2026-03-22T06:58:47Z

We generally avoid C++ streams in GDB sources [1].

Remove an instance of std::ostringstream in arc_check_tdesc_feature.

While we're at it, fix an array index bug:
...
- reg_names << " or '" << reg.names[0] << "'";
+ string_appendf (reg_names, " or '%s'", reg.names[i]);
...

Tested on x86_64-linux, using a trigger patch:
...
- if (!found && reg.required_p)
+ if (true || (!found && reg.required_p))
...
and doing "maint selftest" and observing the output:
...
Running selftest unpack_field_as_long::ARC600.
Error: Cannot find required register(s) 'r0' in feature 'org.gnu.gdb.arc.core'.
Error: Cannot find required register(s) 'pc' in feature 'org.gnu.gdb.arc.aux'.
...

[1] https://sourceware.org/pipermail/gdb-patches/2026-March/226117.html
---
gdb/arc-tdep.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/gdb/arc-tdep.c b/gdb/arc-tdep.c
index ff283014e52..4936a5c8fbb 100644
--- a/gdb/arc-tdep.c
+++ b/gdb/arc-tdep.c
@@ -44,7 +44,6 @@

/* Standard headers. */
#include <algorithm>
-#include <sstream>

/* The frame unwind cache for ARC. */

@@ -2100,16 +2099,16 @@ arc_check_tdesc_feature (struct tdesc_arch_data *tdesc_data,

if (!found && reg.required_p)
{
- std::ostringstream reg_names;
+ std::string reg_names;
for (std::size_t i = 0; i < reg.names.size(); ++i)
{
if (i == 0)
- reg_names << "'" << reg.names[0] << "'";
+ string_appendf (reg_names, "'%s'", reg.names[0]);
else
- reg_names << " or '" << reg.names[0] << "'";
+ string_appendf (reg_names, " or '%s'", reg.names[i]);
}
arc_print (_("Error: Cannot find required register(s) %s "
- "in feature '%s'.\n"), reg_names.str ().c_str (),
+ "in feature '%s'.\n"), reg_names.c_str (),
feature->name.c_str ());
return false;
}

base-commit: d1cb5bd656a253cd69dbcd096f21f658cda697c7
--
2.51.0