rust: Generate per recipe target configuration files

Instead of generating target configuration files centrally and often getting
it wrong, or having trouble finding the right set, generate them dynamically
from the bbclass into WORKDIR per recipe.

(From OE-Core rev: 9160e4a37561d8ac882057450a818621bec13bed)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/cargo.bbclass

@@ -4,6 +4,7 @@
 ## Cargo.
 
 inherit cargo_common
+inherit rust-target-config
 
 # the binary we will use
 CARGO = "cargo"
@@ -40,7 +41,7 @@ BUILD_DIR = "${@['release', 'debug'][d.getVar('DEBUG_BUILD') == '1']}"
 CARGO_TARGET_SUBDIR="${RUST_HOST_SYS}/${BUILD_DIR}"
 oe_cargo_build () {
 	export RUSTFLAGS="${RUSTFLAGS}"
-	export RUST_TARGET_PATH="${RUST_TARGET_PATH}"
+	bbnote "Using rust targets from ${RUST_TARGET_PATH}"
 	bbnote "cargo = $(which ${CARGO})"
 	bbnote "rustc = $(which ${RUSTC})"
 	bbnote "${CARGO} build ${CARGO_BUILD_FLAGS} $@"

meta/classes/rust-bin.bbclass

@@ -93,7 +93,6 @@ do_configure () {
 }
 
 oe_runrustc () {
-	export RUST_TARGET_PATH="${RUST_TARGET_PATH}"
 	bbnote ${RUSTC} ${RUSTC_ARCHFLAGS} ${RUSTC_FLAGS} "$@"
 	"${RUSTC}" ${RUSTC_ARCHFLAGS} ${RUSTC_FLAGS} "$@"
 }

meta/classes/rust-common.bbclass

@@ -1,4 +1,5 @@
 inherit python3native
+inherit rust-target-config
 
 # Common variables used by all Rust builds
 export rustlibdir = "${libdir}/rust"
@@ -10,7 +11,6 @@ RUSTLIB = "-L ${STAGING_LIBDIR}/rust"
 RUST_DEBUG_REMAP = "--remap-path-prefix=${WORKDIR}=/usr/src/debug/${PN}/${EXTENDPE}${PV}-${PR}"
 RUSTFLAGS += "${RUSTLIB} ${RUST_DEBUG_REMAP}"
 RUSTLIB_DEP ?= "libstd-rs"
-export RUST_TARGET_PATH = "${STAGING_LIBDIR_NATIVE}/rustlib"
 RUST_PANIC_STRATEGY ?= "unwind"
 
 # Native builds are not effected by TCLIBC. Without this, rust-native

meta/classes/rust-target-config.bbclass

@@ -292,6 +292,7 @@ def rust_gen_target(d, thing, wd, arch):
     import json
     sys = d.getVar('{}_SYS'.format(thing))
     prefix = d.getVar('{}_PREFIX'.format(thing))
+    rustsys = d.getVar('RUST_{}_SYS'.format(thing))
 
     abi = None
     cpu = "generic"
@@ -318,13 +319,9 @@ def rust_gen_target(d, thing, wd, arch):
     features = features or d.getVarFlag('FEATURES', arch_abi) or ""
     features = features.strip()
 
-    llvm_target = d.getVar('RUST_TARGET_SYS')
-    if thing == "BUILD":
-        llvm_target = d.getVar('RUST_HOST_SYS')
-
     # build tspec
     tspec = {}
-    tspec['llvm-target'] = llvm_target
+    tspec['llvm-target'] = rustsys
     tspec['data-layout'] = d.getVarFlag('DATA_LAYOUT', arch_abi)
     if tspec['data-layout'] is None:
         bb.fatal("No rust target defined for %s" % arch_abi)
@@ -358,7 +355,7 @@ def rust_gen_target(d, thing, wd, arch):
     tspec['panic-strategy'] = d.getVar("RUST_PANIC_STRATEGY")
 
     # write out the target spec json file
-    with open(wd + sys + '.json', 'w') as f:
+    with open(wd + rustsys + '.json', 'w') as f:
         json.dump(tspec, f, indent=4)
 
 # These are accounted for in tmpdir path names so don't need to be in the task sig
@@ -366,10 +363,13 @@ rust_gen_target[vardepsexclude] += "ABIEXTENSION llvm_cpu"
 
 do_rust_gen_targets[vardeps] += "DATA_LAYOUT TARGET_ENDIAN TARGET_POINTER_WIDTH TARGET_C_INT_WIDTH MAX_ATOMIC_WIDTH FEATURES"
 
-RUST_TARGETGENS = "BUILD"
+RUST_TARGETS_DIR = "${WORKDIR}/rust-targets/"
+export RUST_TARGET_PATH = "${RUST_TARGETS_DIR}"
+
+RUST_TARGETGENS = "BUILD HOST TARGET"
 
 python do_rust_gen_targets () {
-    wd = d.getVar('WORKDIR') + '/targets/'
+    wd = d.getVar('RUST_TARGETS_DIR')
     # Order of BUILD, HOST, TARGET is important in case the files overwrite, most specific last
     rust_gen_target(d, 'BUILD', wd, d.getVar('BUILD_ARCH'))
     if "HOST" in d.getVar("RUST_TARGETGENS"):
@@ -379,5 +379,5 @@ python do_rust_gen_targets () {
 }
 
 addtask rust_gen_targets after do_patch before do_compile
-do_rust_gen_targets[dirs] += "${WORKDIR}/targets"
+do_rust_gen_targets[dirs] += "${RUST_TARGETS_DIR}"