sh: Make expansion errors in optimized command substitution non-fatal.

Command substitutions consisting of a single simple command are executed in
the main shell process but this should be invisible apart from performance
and very few exceptions such as $(trap).

1 files changed, 5 insertions, 0 deletions

diff --git a/tools/regression/bin/sh/expansion/cmdsubst5.0 b/tools/regression/bin/sh/expansion/cmdsubst5.0
new file mode 100644
index 0000000..afca371
--- /dev/null
+++ b/tools/regression/bin/sh/expansion/cmdsubst5.0
@@ -0,0 +1,5 @@
+# $FreeBSD$
+
+unset v
+exec 2>/dev/null
+! y=$(: ${v?})