From 59179ef97a590a3a32aa60e33841931040af3edb Mon Sep 17 00:00:00 2001
From: chrysn <chrysn@fsfe.org>
Date: Sat, 3 Apr 2021 17:33:14 +0200
Subject: [PATCH] Rust: Add crates-to-module adapter

---
 makefiles/cargo-settings.inc.mk  |  7 +++++--
 sys/rust_lib_catchall/Cargo.toml | 15 ++++++++++++++
 sys/rust_lib_catchall/Makefile   | 34 ++++++++++++++++++++++++++++++++
 sys/rust_lib_catchall/src/lib.rs | 11 +++++++++++
 4 files changed, 65 insertions(+), 2 deletions(-)
 create mode 100644 sys/rust_lib_catchall/Cargo.toml
 create mode 100644 sys/rust_lib_catchall/Makefile
 create mode 100644 sys/rust_lib_catchall/src/lib.rs

diff --git a/makefiles/cargo-settings.inc.mk b/makefiles/cargo-settings.inc.mk
index 2553184551681..d90f679054a5c 100644
--- a/makefiles/cargo-settings.inc.mk
+++ b/makefiles/cargo-settings.inc.mk
@@ -2,7 +2,10 @@
 #
 # This does not have a sane default, and needs to be set in the architecture
 # files.
-# CARGO_TARGET = ...
+#
+# It is set by the architecture (and thus eventually the CPU), and exported to
+# be available when building Rust modules.
+export CARGO_TARGET
 
 # Flags that need to be added to the RIOT_CFLAGS passed to cargo in order to
 # make bindgen happy
@@ -18,5 +21,5 @@ CARGO_PROFILE ?= release
 # here is to pick a particular nightly when something breaks.
 CARGO_CHANNEL ?= nightly
 
-# The single Rust library to be built.
+# The single Rust library to be built for the application
 CARGO_LIB = target/$(CARGO_TARGET)/${CARGO_PROFILE}/lib$(APPLICATION_RUST_MODULE).a
diff --git a/sys/rust_lib_catchall/Cargo.toml b/sys/rust_lib_catchall/Cargo.toml
new file mode 100644
index 0000000000000..c401d76cae575
--- /dev/null
+++ b/sys/rust_lib_catchall/Cargo.toml
@@ -0,0 +1,15 @@
+[package]
+name = "rust_lib_catchall"
+version = "0.1.0"
+authors = ["Christian Amsüss <chrysn@fsfe.org>"]
+edition = "2018"
+resolver = "2"
+
+[lib]
+crate-type = ["staticlib"]
+
+[dependencies]
+# Provides the panic_handler
+riot-wrappers = "0.7"
+
+riot-shell-commands = { git = "https://gitlab.com/etonomy/riot-module-examples", optional = true }
diff --git a/sys/rust_lib_catchall/Makefile b/sys/rust_lib_catchall/Makefile
new file mode 100644
index 0000000000000..d535c33005890
--- /dev/null
+++ b/sys/rust_lib_catchall/Makefile
@@ -0,0 +1,34 @@
+include $(RIOTBASE)/Makefile.base
+
+# FIXME: These are the defaults; I guess we'll need to pass down everything, and not just CARGO_TARGET
+include ../../makefiles/cargo-settings.inc.mk
+
+# The single Rust library to be built collection modules
+# Not placing this in $(BINDIR)/rust_lib_catchall/target/... as that'd mean
+# that the find in _LINK can catch on to some .o files not intended to be found
+CARGO_LIB_MODULES = $(BINDIR)/rust_lib_catchall-target/$(CARGO_TARGET)/${CARGO_PROFILE}/librust_lib_catchall.a
+
+# FIXME: This is the point where any RIOT modules written in Rust (which would
+# be pseudomodules depending on this) are turned into a list of features to be
+# enabled
+CARGO_OPTIONS += --features riot-shell-commands
+
+$(CARGO_LIB_MODULES): $(RIOTBUILD_CONFIG_HEADER_C) $(BUILDDEPS) FORCE
+	$(Q)[ x"${CARGO_TARGET}" != x"" ] || (echo "Error: No CARGO_TARGET was set for this platform"; exit 1)
+	# differenct to standalone: this uses only CFLAGS and not
+	# CFLAGS_WITGH_MACROS, and then hacks the modules back from the
+	# exported USEMODULE variable (which may generally be a good idea until
+	# compile-commands are available)
+	$(Q)CC= CFLAGS= CPPFLAGS= CXXFLAGS= RIOT_CC="${CC}" RIOT_CFLAGS="$(CFLAGS) $(patsubst %,-DMODULE_%,$(USEMODULE)) $(INCLUDES) $(CARGO_EXTRACFLAGS)" cargo +$(CARGO_CHANNEL) build --target $(CARGO_TARGET) `if [ x$(CARGO_PROFILE) = xrelease ]; then echo --release; else if [ x$(CARGO_PROFILE) '!=' xdebug ]; then echo "--profile $(CARGO_PROFILE)"; fi; fi` $(CARGO_OPTIONS) --target-dir $(BINDIR)/rust_lib_catchall-target
+
+rust_lib_catchall.module: $(CARGO_LIB_MODULES) FORCE
+	$(Q)# Ensure no old object files persist. These would lead to duplicate
+	$(Q)# symbols, or worse, lingering behaivor of XFA entries.
+	$(Q)rm -rf $(BINDIR)/rust_lib_catchall/
+	$(Q)mkdir -p $(BINDIR)/rust_lib_catchall/
+	# difference to standalone: no PWD as it' an absolute path
+	$(Q)cd $(BINDIR)/rust_lib_catchall/ && $(AR) x $<
+
+FORCE:
+
+.PHONY: FORCE
diff --git a/sys/rust_lib_catchall/src/lib.rs b/sys/rust_lib_catchall/src/lib.rs
new file mode 100644
index 0000000000000..2d48825725780
--- /dev/null
+++ b/sys/rust_lib_catchall/src/lib.rs
@@ -0,0 +1,11 @@
+#![no_std]
+
+// As we're pulling all crates in only for their side effects of having symbols (be they required
+// on the Rust side like riot_wrappers' panic_handler, or to be used by RIOT like the XFA symbols
+// emittted by riot-shell-commands), all these crates have to be extern-crate'd to be pulled in
+// even though they're note used on the language level.
+
+extern crate riot_wrappers;
+
+#[cfg(feature = "riot-shell-commands")]
+extern crate riot_shell_commands;