RustCompiledComponentsRecipe`: support for changing toolchain

pythonforandroid/recipe.py

@@ -1353,6 +1353,8 @@ class RustCompiledComponentsRecipe(PyProjectRecipe):
         "x86_64": "x86_64-linux-android",
         "x86": "i686-linux-android",
     }
+    # Rust toolchain to be used for building
+    toolchain = "stable"
 
     call_hostpython_via_targetpython = False
 
@@ -1365,6 +1367,7 @@ def get_recipe_env(self, arch, **kwargs):
             build_target.upper().replace("-", "_")
         )
         env["CARGO_BUILD_TARGET"] = build_target
+        env["TARGET"] = build_target
         env[cargo_linker_name] = join(
             self.ctx.ndk.llvm_prebuilt_dir,
             "bin",
@@ -1386,10 +1389,6 @@ def get_recipe_env(self, arch, **kwargs):
             realpython_dir, "android-build", "build",
             "lib.linux-*-{}/".format(self.python_major_minor_version),
         ))[0])
-
-        info_main("Ensuring rust build toolchain")
-        shprint(sh.rustup, "target", "add", build_target)
-
         # Add host python to PATH
         env["PATH"] = ("{hostpython_dir}:{old_path}").format(
             hostpython_dir=Recipe.get_recipe(
@@ -1399,17 +1398,24 @@ def get_recipe_env(self, arch, **kwargs):
         )
         return env
 
+    def ensure_rust_toolchain(self, arch):
+        info_main("Ensuring rust build toolchain : {}".format(self.toolchain))
+        shprint(sh.rustup, "toolchain", "install", self.toolchain)
+        shprint(sh.rustup, "target", "add", "--toolchain", self.toolchain, self.RUST_ARCH_CODES[arch.arch])
+        shprint(sh.rustup, "default", self.toolchain)
+
     def check_host_deps(self):
         if not hasattr(sh, "rustup"):
             error(
-                "`rustup` was not found on host system."
+                "\n`rustup` was not found on host system."
                 "Please install it using :"
                 "\n`curl https://sh.rustup.rs -sSf | sh`\n"
             )
             exit(1)
 
     def build_arch(self, arch):
         self.check_host_deps()
+        self.ensure_rust_toolchain(arch)
         super().build_arch(arch)