From 0dfc1b508d5e5b361978ef9783cb63775176c305 Mon Sep 17 00:00:00 2001
From: Jeffery To <jeffery.to@gmail.com>
Date: Sat, 23 Sep 2023 20:24:37 +0800
Subject: rust: Use make's jobserver when building packages

This allows cargo to use make's jobserver when building packages, by
marking the cargo command as recursive (with the + prefix[1]) and
setting MAKEFLAGS.

This also:

* Give cargo/x.py the build directory instead of having to change the
  current directory (and opening subshells)

* Set PKG_BUILD_PARALLEL/HOST_BUILD_PARALLEL for Rust packages to enable
  the use of make's jobserver

[1]: https://www.gnu.org/software/make/manual/html_node/POSIX-Jobserver.html

Signed-off-by: Jeffery To <jeffery.to@gmail.com>
---
 lang/rust/rust-host-build.mk | 30 ++++++++++++++----------------
 1 file changed, 14 insertions(+), 16 deletions(-)

(limited to 'lang/rust/rust-host-build.mk')

diff --git a/lang/rust/rust-host-build.mk b/lang/rust/rust-host-build.mk
index 38ce963e0..e56292937 100644
--- a/lang/rust/rust-host-build.mk
+++ b/lang/rust/rust-host-build.mk
@@ -17,29 +17,27 @@ include $(RUST_INCLUDE_DIR)/rust-values.mk
 
 CARGO_HOST_VARS= \
 	$(CARGO_HOST_CONFIG_VARS) \
-	CC=$(HOSTCC_NOCACHE)
+	CC=$(HOSTCC_NOCACHE) \
+	MAKEFLAGS="$(HOST_JOBS)"
 
 # $(1) path to the package (optional)
 # $(2) additional arguments to cargo (optional)
 define Host/Compile/Cargo
-	( \
-		cd $(HOST_BUILD_DIR) ; \
-		$(CARGO_HOST_VARS) \
-		cargo install -v \
-			--profile $(CARGO_HOST_PROFILE) \
-			$(if $(RUST_HOST_FEATURES),--features "$(RUST_HOST_FEATURES)") \
-			--root $(HOST_INSTALL_DIR) \
-			--path "$(if $(strip $(1)),$(strip $(1)),.)" $(2) ; \
-	)
+	+$(CARGO_HOST_VARS) \
+	cargo install -v \
+		--profile $(CARGO_HOST_PROFILE) \
+		$(if $(RUST_HOST_FEATURES),--features "$(RUST_HOST_FEATURES)") \
+		--root $(HOST_INSTALL_DIR) \
+		--path "$(HOST_BUILD_DIR)/$(if $(strip $(1)),$(strip $(1)))" \
+		$(if $(filter --jobserver%,$(HOST_JOBS)),,-j1) \
+		$(2)
 endef
 
 define Host/Uninstall/Cargo
-	( \
-		cd $(HOST_BUILD_DIR) ; \
-		$(CARGO_HOST_VARS) \
-		cargo uninstall -v \
-			--root $(HOST_INSTALL_DIR) || true ; \
-	)
+	+$(CARGO_HOST_VARS) \
+	cargo uninstall -v \
+		--root $(HOST_INSTALL_DIR) \
+		|| true
 endef
 
 define RustBinHostBuild
-- 
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