treewide: Use pkgs/build-support/roles.bash to remove copy pasta

Also fix some setup hooks that unnecessarily used environment hooks,
which revolted in the same variable being modified too many times.

1 files changed, 75 insertions, 0 deletions

diff --git a/pkgs/build-support/setup-hooks/role.bash b/pkgs/build-support/setup-hooks/role.bash
new file mode 100644
index 000000000000..6f1c36f5c050
--- /dev/null
+++ b/pkgs/build-support/setup-hooks/role.bash
@@ -0,0 +1,75 @@
+# Since the same derivation can be depend on in multiple ways, we need to
+# accumulate *each* role (i.e. host and target platforms relative the depending
+# derivation) in which the derivation is used.
+#
+# The role is intened to be use as part of other variables names like
+#  - $NIX_${role_pre}_SOMETHING
+#  - $NIX_SOMETHING_${role_post}
+
+function getRole() {
+    case $1 in
+        -1)
+            role_pre='BUILD_'
+            role_post='_FOR_BUILD'
+            ;;
+        0)
+            role_pre=''
+            role_post=''
+            ;;
+        1)
+            role_pre='TARGET_'
+            role_post='_FOR_TARGET'
+            ;;
+        *)
+            echo "@name@: used as improper sort of dependency" >2
+            return 1
+            ;;
+    esac
+}
+
+# `hostOffset` describes how the host platform of the package is slid relative
+# to the depending package. `targetOffset` likewise describes the target
+# platform of the package. Both are brought into scope of the setup hook defined
+# for dependency whose setup hook is being processed relative to the package
+# being built.
+
+function getHostRole()   {
+    getRole "$hostOffset"
+}
+function getTargetRole() {
+    getRole "$targetOffset"
+}
+
+# `depHostOffset` describes how the host platform of the dependencies are slid
+# relative to the depending package. `depTargetOffset` likewise describes the
+# target platform of dependenices. Both are brought into scope of the
+# environment hook defined for the dependency being applied relative to the
+# package being built.
+
+function getHostRoleEnvHook()   {
+    getRole "$depHostOffset"
+}
+function getTargetRoleEnvHook() {
+    getRole "$depTargetOffset"
+}
+
+# This variant is inteneded specifically for code-prodocing tool wrapper scripts
+# `NIX_@wrapperName@_@infixSalt@_TARGET_*` tracks this (needs to be an exported
+# env var so can't use fancier data structures).
+function getTargetRoleWrapper() {
+    case $targetOffset in
+        -1)
+            export NIX_@wrapperName@_@infixSalt@_TARGET_BUILD=1
+            ;;
+        0)
+            export NIX_@wrapperName@_@infixSalt@_TARGET_HOST=1
+            ;;
+        1)
+            export NIX_@wrapperName@_@infixSalt@_TARGET_TARGET=1
+            ;;
+        *)
+            echo "@name@: used as improper sort of dependency" >2
+            return 1
+            ;;
+    esac
+}