Fix Proc#inspect for a Symbol#to_proc Proc

Author: eregon

src/main/java/org/truffleruby/core/proc/ProcNodes.java

@@ -14,10 +14,13 @@
 import org.truffleruby.builtins.CoreClass;
 import org.truffleruby.builtins.CoreMethod;
 import org.truffleruby.builtins.CoreMethodArrayArgumentsNode;
+import org.truffleruby.builtins.Primitive;
+import org.truffleruby.builtins.PrimitiveArrayArgumentsNode;
 import org.truffleruby.builtins.UnaryCoreMethodNode;
 import org.truffleruby.core.binding.BindingNodes;
 import org.truffleruby.core.rope.CodeRange;
 import org.truffleruby.core.string.StringNodes;
+import org.truffleruby.core.symbol.SymbolNodes;
 import org.truffleruby.language.NotProvided;
 import org.truffleruby.language.Visibility;
 import org.truffleruby.language.arguments.ArgumentDescriptorUtils;
@@ -280,4 +283,18 @@ public Object sourceLocation(DynamicObject proc) {
 
     }
 
+    @Primitive(name = "proc_symbol_to_proc_symbol")
+    public abstract static class ProcSymbolToProcSymbolNode extends PrimitiveArrayArgumentsNode {
+
+        @Specialization
+        public DynamicObject symbolToProcSymbol(DynamicObject proc) {
+            if (Layouts.PROC.getSharedMethodInfo(proc).getArity() == SymbolNodes.ToProcNode.ARITY) {
+                return getSymbol(Layouts.PROC.getSharedMethodInfo(proc).getName());
+            } else {
+                return nil();
+            }
+        }
+
+    }
+
 }

src/main/java/org/truffleruby/core/symbol/SymbolNodes.java

@@ -95,6 +95,8 @@ protected boolean isPreInitializing() {
     @CoreMethod(names = "to_proc")
     public abstract static class ToProcNode extends CoreMethodArrayArgumentsNode {
 
+        public static final Arity ARITY = new Arity(0, 0, true);
+
         @Child private ReadCallerFrameNode readCallerFrame = ReadCallerFrameNode.create();
 
         @Specialization(guards = { "cachedSymbol == symbol", "getDeclarationContext(frame) == cachedDeclarationContext" }, limit = "getCacheLimit()")
@@ -120,7 +122,7 @@ protected DynamicObject createProc(DeclarationContext declarationContext, Intern
             final SharedMethodInfo sharedMethodInfo = new SharedMethodInfo(
                     sourceSection,
                     method.getLexicalScope(),
-                    Arity.REST,
+                    ARITY,
                     null,
                     Layouts.SYMBOL.getString(symbol),
                     0,

src/main/java/org/truffleruby/language/methods/Arity.java

@@ -21,7 +21,6 @@ public class Arity {
     public static final String[] NO_KEYWORDS = new String[]{};
     public static final Arity NO_ARGUMENTS = new Arity(0, 0, false);
     public static final Arity ONE_REQUIRED = new Arity(1, 0, false);
-    public static final Arity REST = new Arity(0, 0, true);
 
     private final int preRequired;
     private final int optional;

src/main/ruby/core/proc.rb

@@ -90,7 +90,11 @@ def to_s
     file, line = source_location
 
     suffix = "".b
-    suffix << "@#{file}:#{line}" if file and line
+    if sym = Truffle.invoke_primitive(:proc_symbol_to_proc_symbol, self)
+      suffix << "(&#{sym.inspect})"
+    elsif file and line
+      suffix << "@#{file}:#{line}"
+    end
     suffix << ' (lambda)' if lambda?
     base.b.insert -2, suffix
   end