Make it easier to opt-in from extconf

oxidize-rb · Jul 12, 2023 · ddc8868 · ddc8868
1 parent 497e5fe
commit ddc8868
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Showing 5 changed files with 22 additions and 5 deletions.
diff --git a/crates/rb-sys/build/features.rs b/crates/rb-sys/build/features.rs
@@ -26,8 +26,11 @@ pub fn is_compiled_stable_api_needed(ver: &Version) -> bool {
 }
 
 pub fn explicitly_enabled_stable_api_compiled_fallback() -> bool {
-    cfg!(rb_sys_use_stable_api_compiled_fallback)
-        || is_env_variable_defined("CARGO_FEATURE_STABLE_API_COMPILED_FALLBACK")
+    println!("cargo:rerun-if-env-changed=RB_SYS_USE_STABLE_API_COMPILED_FALLBACK");
+
+    is_env_variable_defined("CARGO_FEATURE_STABLE_API_COMPILED_FALLBACK")
+        || cfg!(rb_sys_use_stable_api_compiled_fallback)
+        || is_env_variable_defined("RB_SYS_USE_STABLE_API_COMPILED_FALLBACK")
 }
 
 pub fn testing_stable_api_compiled_fallback() -> bool {

diff --git a/examples/rust_reverse/ext/rust_reverse/extconf.rb b/examples/rust_reverse/ext/rust_reverse/extconf.rb
@@ -20,7 +20,7 @@
   r.ext_dir = "."
 
   # Extra flags to pass to the $RUSTFLAGS environment variable (optional)
-  r.extra_rustflags << "--cfg=rb_sys_use_stable_api_compiled_fallback"
+  r.extra_rustflags << "--cfg=some_nested_config_var_for_crate"
 
   # Force a rust toolchain to be installed via rustup (optional)
   # You can also set the env var `RB_SYS_FORCE_INSTALL_RUST_TOOLCHAIN=true`
@@ -34,4 +34,7 @@
 
   # Extra targets to install via rustup (optional)
   r.extra_rustup_targets = ["wasm32-unknown-unknown"]
+
+  # Enable stable API compiled fallback for ruby-head (optional)
+  r.use_stable_api_compiled_fallback = true
 end
diff --git a/examples/rust_reverse/ext/rust_reverse/extconf_bare.rb b/examples/rust_reverse/ext/rust_reverse/extconf_bare.rb
@@ -6,5 +6,6 @@
 require "rb_sys/mkmf"
 
 create_rust_makefile("rust_reverse") do |r|
-  r.extra_rustflags << "--cfg=rb_sys_use_stable_api_compiled_fallback"
+  # Enable stable API compiled fallback for ruby-head (optional)
+  r.use_stable_api_compiled_fallback = true
 end
diff --git a/gem/lib/rb_sys/mkmf.rb b/gem/lib/rb_sys/mkmf.rb
@@ -53,6 +53,8 @@ def create_rust_makefile(target, &blk)
       RbConfig.expand(srcdir = srcprefix.dup)
 
       full_cargo_command = cargo_command(srcdir, builder)
+      global_rustflags = GLOBAL_RUSTFLAGS.dup
+      global_rustflags << "--cfg=rb_sys_use_stable_api_compiled_fallback" if builder.use_stable_api_compiled_fallback?
 
       make_install = +<<~MAKE
         #{conditional_assign("RB_SYS_BUILD_DIR", File.join(Dir.pwd, ".rb-sys"))}
@@ -68,7 +70,7 @@ def create_rust_makefile(target, &blk)
 
         #{set_cargo_profile(builder)}
         #{conditional_assign("RB_SYS_CARGO_FEATURES", builder.features.join(","))}
-        #{conditional_assign("RB_SYS_GLOBAL_RUSTFLAGS", GLOBAL_RUSTFLAGS.join(" "))}
+        #{conditional_assign("RB_SYS_GLOBAL_RUSTFLAGS", global_rustflags.join(" "))}
         #{conditional_assign("RB_SYS_EXTRA_RUSTFLAGS", builder.extra_rustflags.join(" "))}
         #{conditional_assign("RB_SYS_EXTRA_CARGO_ARGS", builder.extra_cargo_args.join(" "))}
         #{conditional_assign("RB_SYS_CARGO_MANIFEST_DIR", builder.manifest_dir)}

diff --git a/gem/lib/rb_sys/mkmf/config.rb b/gem/lib/rb_sys/mkmf/config.rb
@@ -22,10 +22,14 @@ class Config
       # Extra targets to install
       attr_accessor :extra_rustup_targets
 
+      # Use compiled C code fallback for stable API for ruby-head (default: false)
+      attr_accessor :use_stable_api_compiled_fallback
+
       def initialize(builder)
         @builder = builder
         @force_install_rust_toolchain = false
         @auto_install_rust_toolchain = true
+        @use_stable_api_compiled_fallback = false
         @clean_after_install = rubygems_invoked?
         @rubygems_clean_dirs = ["./cargo-vendor"]
         @extra_rustup_targets = []
@@ -53,6 +57,10 @@ def respond_to_missing?(name, include_private = false)
       def rubygems_invoked?
         ENV.key?("SOURCE_DATE_EPOCH")
       end
+
+      def use_stable_api_compiled_fallback?
+        @use_stable_api_compiled_fallback
+      end
     end
   end
 end