[PATCH] Fix "unset local-environment" when clearenv not available

Tom Tromey
2025-12-10T16:24:34Z

Tom de Vries pointed out that clearenv isn't available on all hosts.
Since this seems like a niche command at best, it seemed fine to
disable this command on such platforms.
---
gdb/config.in | 3 +++
gdb/configure | 1 +
gdb/configure.ac | 1 +
gdb/infcmd.c | 15 ++++++++++++++-
gdb/testsuite/gdb.base/local-env.exp | 24 +++++++++++++++++++-----
5 files changed, 38 insertions(+), 6 deletions(-)

diff --git a/gdb/config.in b/gdb/config.in
index 9e2bba42e28..62d9e0eda6d 100644
--- a/gdb/config.in
+++ b/gdb/config.in
@@ -110,6 +110,9 @@
the CoreFoundation framework. */
#undef HAVE_CFPREFERENCESCOPYAPPVALUE

+/* Define to 1 if you have the `clearenv' function. */
+#undef HAVE_CLEARENV
+
/* Define if compiling support to gdb compile. */
#undef HAVE_COMPILE

diff --git a/gdb/configure b/gdb/configure
index cc446c6e4c8..dcf4fee40dd 100755
--- a/gdb/configure
+++ b/gdb/configure
@@ -30123,6 +30123,7 @@ $as_echo "#define AC_APPLE_UNIVERSAL_BUILD 1" >>confdefs.h

for ac_func in \
btowc \
+ clearenv \
getgid \
getpgid \
getrlimit \
diff --git a/gdb/configure.ac b/gdb/configure.ac
index 1b9939b0754..3f44d9e684b 100644
--- a/gdb/configure.ac
+++ b/gdb/configure.ac
@@ -1458,6 +1458,7 @@ AC_C_BIGENDIAN

AC_CHECK_FUNCS([ \
btowc \
+ clearenv \
getgid \
getpgid \
getrlimit \
diff --git a/gdb/infcmd.c b/gdb/infcmd.c
index 3ba286738a0..ed4fb819faf 100644
--- a/gdb/infcmd.c
+++ b/gdb/infcmd.c
@@ -2146,12 +2146,25 @@ unset_var_in_environment (gdb_environ *env, const char *var, int from_tty)
{
if (var == 0)
{
+ /* If there is no clearenv, don't bother asking the question. */
+#ifndef HAVE_CLEARENV
+ if (env == nullptr)
+ from_tty = 0;
+#endif
+
/* If there is no argument, delete all environment variables.
Ask for confirmation if reading from the terminal. */
if (!from_tty || query (_("Delete all environment variables? ")))
{
+ /* This was handled above. */
if (env == nullptr)
- clearenv ();
+ {
+#ifdef HAVE_CLEARENV
+ clearenv ();
+#else
+ error (_("Cannot clear the local environment on this host."));
+#endif
+ }
else
env->clear ();
}
diff --git a/gdb/testsuite/gdb.base/local-env.exp b/gdb/testsuite/gdb.base/local-env.exp
index fedcf9bc3e4..5bb639e2842 100644
--- a/gdb/testsuite/gdb.base/local-env.exp
+++ b/gdb/testsuite/gdb.base/local-env.exp
@@ -59,12 +59,26 @@ gdb_test "show local-environment EDITOR" \
"confirm unset environment variable worked"

# Verify that we can unset all environment variables.
-gdb_test "unset local-environment" "" "unset all environment variables" \
- "Delete all environment variables. .y or n. $" \
- "y"
+# Note that on some platforms this is not possible.
+set can_unset_all 0
+# Disable confirmation so we don't have to deal with the question.
+gdb_test_multiple "with confirm off -- unset local-environment" \
+ "unset all environment variables" {
+ -re -wrap "Cannot clear the local environment on this host." {
+ # Nothing.
+ pass $gdb_test_name
+ }
+
+ -re "\r\n$gdb_prompt $" {
+ set can_unset_all 1
+ pass $gdb_test_name
+ }
+ }

-gdb_test_no_output "show local-environment" \
- "all environment variables have been unset"
+if {$can_unset_all} {
+ gdb_test_no_output "show local-environment" \
+ "all environment variables have been unset"
+}

# Verify that we can set a specific environment variable.
test_set_show_env_var "EDITOR" "emacs" "set environment variable"

base-commit: 7979dbef836b1c8035b9fe9dd6e09c342d85a5e2
--
2.52.0