[ruby-core:111015] [Ruby master Feature#19138] `SyntaxError#path` for syntax_suggest

["schneems (Richard Schneeman)" <noreply@ruby-lang.org>]

Issue #19138 has been updated by schneems (Richard Schneeman).


I love the idea.

Instead of adding #line though if we could attach the source that would be more impactful for syntax search.

Some cases such as eval do not have source files, so if we could access the contents for casses without a path that would increase the capabilities of the gem.

----------------------------------------
Feature #19138: `SyntaxError#path` for syntax_suggest
https://bugs.ruby-lang.org/issues/19138#change-100269

* Author: nobu (Nobuyoshi Nakada)
* Status: Open
* Priority: Normal
----------------------------------------
Currently syntax_suggest searches the path name from the exception message.
But extracting the info from messages for humans is fragile, I think.
So proposing a new method `SyntaxError#path`, similar to `LoadError#path`.

```patch
commit 986da132002af1cdb75c0c89ca2831fe51e6ce69
Author:     Nobuyoshi Nakada <nobu@ruby-lang.org>
AuthorDate: 2022-11-20 22:59:52 +0900
Commit:     Nobuyoshi Nakada <nobu@ruby-lang.org>
CommitDate: 2022-11-20 23:44:27 +0900

    Add `SyntaxError#path`

diff --git a/error.c b/error.c
index 0ff4b8d6d8e..ad1bc6ee8dc 100644
--- a/error.c
+++ b/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)) {
-            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");
-        }
+        exc = syntax_error_with_path(exc, file, &mesg, enc);
         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);
 
```

With this method, syntax_suggest/core_ext.rb will no longer need `PathnameFromMessage`.

```patch
diff --git i/lib/syntax_suggest/core_ext.rb w/lib/syntax_suggest/core_ext.rb
index 40f5fe13759..616a6ed9839 100644
--- i/lib/syntax_suggest/core_ext.rb
+++ w/lib/syntax_suggest/core_ext.rb
@@ -25,15 +25,12 @@
       require "syntax_suggest/api" unless defined?(SyntaxSuggest::DEFAULT_VALUE)
 
       message = super
-      file = if highlight
-        SyntaxSuggest::PathnameFromMessage.new(super(highlight: false, **kwargs)).call.name
-      else
-        SyntaxSuggest::PathnameFromMessage.new(message).call.name
-      end
-
-      io = SyntaxSuggest::MiniStringIO.new
+      file = path
 
       if file
+        file = Pathname.new(file)
+        io = SyntaxSuggest::MiniStringIO.new
+
         SyntaxSuggest.call(
           io: io,
           source: file.read,
```

Since we have not released with `SyntaxError#detailed_message` yet, there should not be a compatibility issue.

@schneems How do you think?





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