From 23784a4ebded05212fcc3196e487abbfaa5c5bfe Mon Sep 17 00:00:00 2001
From: Rusty Russell <rusty@rustcorp.com.au>
Date: Tue, 14 Oct 2025 09:41:14 +1030
Subject: [PATCH] configure: set SED to gsed (MacOS et al) or sed (GNU).

We use some GNU sed features and it's easier to require gsed than fix
them all (and keep noticing when they break).  MacOS comes with gsed
already!

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
---
 configure | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/configure b/configure
index 7375b3d4f..10ab17629 100755
--- a/configure
+++ b/configure
@@ -82,6 +82,24 @@ default_python()
     done
 }
 
+# We want GNU sed, which, among other things, recognizes '\t'.
+# We don't want to get confused with some random program called gsed,
+# so we actually test.
+default_sed()
+{
+    SED_BINS="gsed sed"
+    for s in $SED_BINS; do
+        if [ "$(which $s)" != "" ] ; then
+            if [ "$(printf x | $s 's/x/\t/')" = "	" ]; then
+		echo "$s"
+                return
+            fi
+        fi
+    done
+    echo "No valid sed found?" >&2
+    exit 1
+}
+
 # Takes PYTHON var
 default_pytest()
 {
@@ -184,6 +202,7 @@ set_defaults()
     fi
     echo CSANFLAGS = $CSANFLAGS
     PYTHON=${PYTHON-$(default_python)}
+    SED=${SED-$(default_sed)}
     PYTEST=${PYTEST-$(default_pytest $PYTHON)}
     COPTFLAGS=${COPTFLAGS-$(default_coptflags "$DEBUGBUILD")}
     CONFIGURATOR_CC=${CONFIGURATOR_CC-$CC}
@@ -212,6 +231,7 @@ usage()
     echo "    To override compile line for configurator itself"
     usage_with_default "PYTEST" "$PYTEST"
     usage_with_default "VALGRIND" "$VALGRIND"
+    usage_with_default "SED" "$SED"
 
     echo "Options include:"
     usage_with_default "--prefix=" "$PREFIX"
@@ -554,6 +574,7 @@ add_var SHA256SUM "$SHA256SUM"
 add_var FUZZING "$FUZZING"
 add_var RUST "$RUST"
 add_var PYTHON "$PYTHON"
+add_var SED "$SED"
 
 # Hack to avoid sha256 name clash with libwally: will be fixed when that
 # becomes a standalone shared lib.