Optimize feature loading when require is called with absolute .rb path

If require is called with an absolute path like `/path/to/thing.rb`
we can try that as is first rather than trying `.rb.rb` and `.rb.so` first.

Add require specs for absolute paths:
- with no extension (RB ext and C ext)
- .so becomes .bundle on darwin

CHANGELOG.md

@@ -16,6 +16,7 @@ Compatibility:
 Performance:
 
 * Optimize calls with `ruby2_keywords` forwarding by deciding it per call site instead of per callee thanks to [my fix in CRuby 3.2](https://bugs.ruby-lang.org/issues/18625) (@eregon).
+* Optimize feature loading when require is called with an absolute path to a .rb file (@rwstauner).
 
 Changes:
 

spec/ruby/core/kernel/shared/require.rb

@@ -25,6 +25,27 @@
       ScratchPad.recorded.should == []
     end
 
+    it "loads .rb file when passed absolute path without extension" do
+      path = File.expand_path "load_fixture", CODE_LOADING_DIR
+      @object.send(@method, path).should be_true
+      # This should _not_ be [:no_ext]
+      ScratchPad.recorded.should == [:loaded]
+    end
+
+    it "loads c-extension file when passed absolute path without extension when no .rb is present" do
+      path = File.join CODE_LOADING_DIR, "a", "load_fixture"
+      @object.send(@method, path).should be_true
+      ScratchPad.recorded.first.to_s.should =~ /^ext_/
+    end
+
+    platform_is :darwin do
+      it "loads .bundle file when passed absolute path with .so" do
+        path = File.join CODE_LOADING_DIR, "a", "load_fixture.so"
+        @object.send(@method, path).should be_true
+        ScratchPad.recorded.should == [:ext_bundle]
+      end
+    end
+
     # Can't make a file unreadable on these platforms
     platform_is_not :windows, :cygwin do
       as_user do

src/main/java/org/truffleruby/language/loader/FeatureLoader.java

@@ -379,27 +379,29 @@ private String translateIfNativePath(String feature) {
     private String findFeatureWithAndWithoutExtension(String path) {
         assert new File(path).isAbsolute();
 
-        if (path.endsWith(".so")) {
-            final String pathWithNativeExt = translateIfNativePath(path);
-            final String asCExt = findFeatureWithExactPath(pathWithNativeExt);
-            if (asCExt != null) {
-                return asCExt;
+        if (hasExtension(path)) {
+            if (path.endsWith(".so")) {
+                final String pathWithNativeExt = translateIfNativePath(path);
+                final String asCExt = findFeatureWithExactPath(pathWithNativeExt);
+                if (asCExt != null) {
+                    return asCExt;
+                }
             }
-        }
 
-        final String asRuby = findFeatureWithExactPath(path + TruffleRuby.EXTENSION);
-        if (asRuby != null) {
-            return asRuby;
-        }
-
-        final String asCExt = findFeatureWithExactPath(path + RubyLanguage.CEXT_EXTENSION);
-        if (asCExt != null) {
-            return asCExt;
-        }
+            final String withoutExtension = findFeatureWithExactPath(path);
+            if (withoutExtension != null) {
+                return withoutExtension;
+            }
+        } else {
+            final String asRuby = findFeatureWithExactPath(path + TruffleRuby.EXTENSION);
+            if (asRuby != null) {
+                return asRuby;
+            }
 
-        final String withoutExtension = findFeatureWithExactPath(path);
-        if (withoutExtension != null) {
-            return withoutExtension;
+            final String asCExt = findFeatureWithExactPath(path + RubyLanguage.CEXT_EXTENSION);
+            if (asCExt != null) {
+                return asCExt;
+            }
         }
 
         return null;