Fix some warnings (#379)

build_extra/flatbuffers/BUILD.gn

@@ -13,6 +13,10 @@ config("flatbuffers_config") {
     cflags = [
       "-Wno-exit-time-destructors",
       "-Wno-header-hygiene",
+
+      # TODO: rust branch of flatbuffers has this warning.
+      # This should be removed when the branch fixed.
+      "-Wno-return-type",
     ]
   }
 }

build_extra/rust/BUILD.gn

@@ -26,6 +26,13 @@ rust_component("url") {
 
 rust_component("percent_encoding") {
   source_root = "$crates/registry/src/github.com-1ecc6299db9ec823/percent-encoding-1.0.1/lib.rs"
+  args = [
+    # TODO: Suppress some warnings at this moment
+    # This should be removed when it's fixed in servo/rust-url repository
+    # https://github.com/servo/rust-url/issues/455
+    "-Aunused-imports",
+    "-Adeprecated",
+  ]
 }
 
 rust_component("matches") {

build_extra/rust/rust.gni

@@ -62,11 +62,14 @@ template("run_rustc") {
     outputs = []
     script = "//tools/run_rustc.py"
 
+    # TODO: We want to apply "-Dwarnings" only when treat_warnings_as_errors is not false
+    # https://github.com/ry/deno/pull/379
     args = [
       rebase_path(source_root, root_build_dir),
       "--crate-name=$crate_name",
       "--crate-type=$crate_type",
     ]
+
     if (!is_win) {
       args += [ "--color=always" ]
     }
@@ -116,6 +119,10 @@ template("run_rustc") {
       }
     }
 
+    if (defined(invoker.args)) {
+      args += invoker.args
+    }
+
     if (!defined(deps)) {
       deps = []
     }
@@ -155,6 +162,7 @@ template("rust_component") {
                              "source_root",
                              "is_test",
                              "testonly",
+                             "args",
                            ])
     if (!defined(invoker.crate_type)) {
       crate_type = "rlib"