makeWrapper: add --set-default and --set-eval

After #31497 starter quoting all values, there arouse the need to left some
values evaluated.

`--set-default var value` expands to `export var=${var-value}`, where value is
not evaluated and literally assigned to var unless it is already set.

`--set-eval var value` expands to `export var=$(eval echo value)`, where value
is evaluated by `eval`.

1 files changed, 10 insertions, 0 deletions

diff --git a/pkgs/build-support/setup-hooks/make-wrapper.sh b/pkgs/build-support/setup-hooks/make-wrapper.sh
index 01410828d39d..ab24fb38b29e 100644
--- a/pkgs/build-support/setup-hooks/make-wrapper.sh
+++ b/pkgs/build-support/setup-hooks/make-wrapper.sh
@@ -48,6 +48,16 @@ makeWrapper() {
             value="${params[$((n + 2))]}"
             n=$((n + 2))
             echo "export $varName=${value@Q}" >> "$wrapper"
+        elif [[ "$p" == "--set-default" ]]; then
+            varName="${params[$((n + 1))]}"
+            value="${params[$((n + 2))]}"
+            n=$((n + 2))
+            echo "export $varName=\${$varName-${value@Q}}" >> "$wrapper"
+        elif [[ "$p" == "--set-eval" ]]; then
+            varName="${params[$((n + 1))]}"
+            value="${params[$((n + 2))]}"
+            n=$((n + 2))
+            echo "export $varName=\$(eval echo ${value@Q})" >> "$wrapper"
         elif [[ "$p" == "--unset" ]]; then
             varName="${params[$((n + 1))]}"
             n=$((n + 1))