[Feature #19138] Add SyntaxError#path

Merged: https://github.com/ruby/ruby/pull/6779

NEWS.md

@@ -300,6 +300,9 @@ Note: We're only listing outstanding class updates.
     * Time#deconstruct_keys is added, allowing to use Time instances
       in pattern-matching expressions [[Feature #19071]]
 
+* SyntaxError
+    * SyntaxError#path has been added.  [[Bug #19138]]
+
 * TracePoint
 
     * TracePoint#binding now returns `nil` for `c_call`/`c_return` TracePoints.
@@ -551,3 +554,4 @@ The following deprecated APIs are removed.
 [Feature #19071]: https://bugs.ruby-lang.org/issues/19071
 [Bug #19100]:     https://bugs.ruby-lang.org/issues/19100
 [Feature #19135]: https://bugs.ruby-lang.org/issues/19135
+[Feature #19138]: https://bugs.ruby-lang.org/issues/19138

error.c

@@ -125,6 +125,8 @@ err_vcatf(VALUE str, const char *pre, const char *file, int line,
     return str;
 }
 
+static VALUE syntax_error_with_path(VALUE, VALUE, VALUE*, rb_encoding*);
+
 VALUE
 rb_syntax_error_append(VALUE exc, VALUE file, int line, int column,
                        rb_encoding *enc, const char *fmt, va_list args)
@@ -138,15 +140,7 @@ rb_syntax_error_append(VALUE exc, VALUE file, int line, int column,
     }
     else {
         VALUE mesg;
-        if (NIL_P(exc)) {
+        exc = syntax_error_with_path(exc, file, &mesg, enc);
-            mesg = rb_enc_str_new(0, 0, enc);
-            exc = rb_class_new_instance(1, &mesg, rb_eSyntaxError);
-        }
-        else {
-            mesg = rb_attr_get(exc, idMesg);
-            if (RSTRING_LEN(mesg) > 0 && *(RSTRING_END(mesg)-1) != '\n')
-                rb_str_cat_cstr(mesg, "\n");
-        }
         err_vcatf(mesg, NULL, fn, line, fmt, args);
     }
 
@@ -2353,6 +2347,25 @@ syntax_error_initialize(int argc, VALUE *argv, VALUE self)
     return rb_call_super(argc, argv);
 }
 
+static VALUE
+syntax_error_with_path(VALUE exc, VALUE path, VALUE *mesg, rb_encoding *enc)
+{
+    if (NIL_P(exc)) {
+        *mesg = rb_enc_str_new(0, 0, enc);
+        exc = rb_class_new_instance(1, mesg, rb_eSyntaxError);
+        rb_ivar_set(exc, id_i_path, path);
+    }
+    else {
+        if (rb_attr_get(exc, id_i_path) != path) {
+            rb_raise(rb_eArgError, "SyntaxError#path changed");
+        }
+        VALUE s = *mesg = rb_attr_get(exc, idMesg);
+        if (RSTRING_LEN(s) > 0 && *(RSTRING_END(s)-1) != '\n')
+            rb_str_cat_cstr(s, "\n");
+    }
+    return exc;
+}
+
 /*
  *  Document-module: Errno
  *
@@ -3011,9 +3024,14 @@ Init_Exception(void)
     rb_eSyntaxError = rb_define_class("SyntaxError", rb_eScriptError);
     rb_define_method(rb_eSyntaxError, "initialize", syntax_error_initialize, -1);
 
+    ID id_path = rb_intern_const("path");
+
+    /* the path failed to parse */
+    rb_attr(rb_eSyntaxError, id_path, TRUE, FALSE, FALSE);
+
     rb_eLoadError   = rb_define_class("LoadError", rb_eScriptError);
     /* the path failed to load */
-    rb_attr(rb_eLoadError, rb_intern_const("path"), TRUE, FALSE, FALSE);
+    rb_attr(rb_eLoadError, id_path, TRUE, FALSE, FALSE);
 
     rb_eNotImpError = rb_define_class("NotImplementedError", rb_eScriptError);
 

test/ruby/test_exception.rb

@@ -1487,4 +1487,27 @@ $stderr = $stdout; raise "\x82\xa0"') do |outs, errs, status|
       end
     end
   end
+
+  def test_syntax_error_path
+    e = assert_raise(SyntaxError) {
+      eval("1+", nil, "test_syntax_error_path.rb")
+    }
+    assert_equal("test_syntax_error_path.rb", e.path)
+
+    Dir.mktmpdir do |dir|
+      lib = File.join(dir, "syntax_error-path.rb")
+      File.write(lib, "#{<<~"begin;"}\n#{<<~'end;'}")
+      begin;
+        class SyntaxError
+          def detailed_message(**)
+            STDERR.puts "\n""path=#{path}\n"
+            super
+          end
+        end
+      end;
+      main = File.join(dir, "syntax_error.rb")
+      File.write(main, "1+\n")
+      assert_in_out_err(%W[-r#{lib} #{main}], "", [], [:*, "\n""path=#{main}\n", :*])
+    end
+  end
 end