bug#22358: 24.5; Analysis and indentation of Java default interface methods incorrect

bug#22358: 24.5; Analysis and indentation of Java default interface methods incorrect

[Lanning]

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Consider the Java interface

    public interface IndentDefaultInterfaceMethod {
        String doSomething(Foo foo);
        // The"default" in the next line is *not* a case tag...
        default String doSomething() {
            return doSomething(Foo.getDefaultFoo());
        }
    } // IndentDefaultInterfaceMethod

Syntactic analysis of the "default" line declares it a case-label.
As a result it gets indented to align with the "public" modifier.

Instead it should (probably) be treated the same as an access modifier.
But boy howdy is that code in c-guess-basic-syntax complicated!




In GNU Emacs 24.5.1 (x86_64-pc-linux-gnu, GTK+ Version 3.16.6)
 of 2015-09-17 on lgw01-52, modified by Debian
Windowing system distributor `The X.Org Foundation', version 11.0.11702000
System Description: Ubuntu 15.10

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Followed link to
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Syntactic analysis: ((case-label 1262))
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bug#22358: 24.5; Analysis and indentation of Java default interface methods incorrect

[Alan Mackenzie]

Hello, Lanning.

In article <mailman.2245.1452630247.843.bug-gnu-emacs@gnu.org> you wrote:
> [-- text/plain, encoding 7bit, charset: UTF-8, 141 lines --]

> Consider the Java interface

>     public interface IndentDefaultInterfaceMethod {
>         String doSomething(Foo foo);
>         // The"default" in the next line is *not* a case tag...
>         default String doSomething() {
>             return doSomething(Foo.getDefaultFoo());
>         }
>     } // IndentDefaultInterfaceMethod

> Syntactic analysis of the "default" line declares it a case-label.
> As a result it gets indented to align with the "public" modifier.

Yes.  First of all, thanks for taking the trouble to report this problem,
and thanks even more for distilling it into a nice short test case which
is easy to work with.

Please see the patch below.  After applying it, it is utterly
essential to recompile several files in CC Mode, to ensure that a change
to one of the macros in cc-langs.el is propagated through the rest of the
code.  So after applying the patch (in directory
.../emacs-24.5/lisp/progmodes), compile as follows

$ emacs -Q -batch -f batch-byte-compile cc-*.el

.

> Instead it should (probably) be treated the same as an access modifier.
> But boy howdy is that code in c-guess-basic-syntax complicated!

:-)  Actually, c-guess-basic-syntax is relatively simple, it's just long,
long, long; it's little more than a big `cond' form.  The place where the
current bug was happening was at "CASE 14: A case or default label",
where a match happened with no more checking than seeing the keyword
"default".  I've added more rigorous checking to that.

Would you please let me know whether the patch solves the problem
completely, or whether there are still issues with it remaining to be
fixed.

Thanks!

> In GNU Emacs 24.5.1 (x86_64-pc-linux-gnu, GTK+ Version 3.16.6)
>  of 2015-09-17 on lgw01-52, modified by Debian
> Windowing system distributor `The X.Org Foundation', version 11.0.11702000
> System Description: Ubuntu 15.10

OK, here's the patch:



diff -r 03dea479cb53 cc-engine.el
--- a/cc-engine.el	Tue Jan 12 17:50:29 2016 +0000
+++ b/cc-engine.el	Wed Jan 13 22:26:10 2016 +0000
@@ -9782,7 +9782,20 @@
 				       paren-state)))
 
        ;; CASE 14: A case or default label
-       ((looking-at c-label-kwds-regexp)
+       ((save-excursion
+	  (and (looking-at c-label-kwds-regexp)
+	       (or (c-major-mode-is 'idl-mode)
+		   (and
+		    containing-sexp
+		    (goto-char containing-sexp)
+		    (eq (char-after) ?{)
+		    (progn (c-backward-syntactic-ws) t)
+		    (eq (char-before) ?\))
+		    (c-go-list-backward)
+		    (progn (c-backward-syntactic-ws) t)
+		    (c-simple-skip-symbol-backward)
+		    (looking-at c-block-stmt-2-key)))
+	     ))
 	(if containing-sexp
 	    (progn
 	      (goto-char containing-sexp)
@@ -9798,6 +9811,7 @@
        ((save-excursion
 	  (back-to-indentation)
 	  (and (not (looking-at c-syntactic-ws-start))
+	       (not (looking-at c-label-kwds-regexp))
 	       (c-forward-label)))
 	(cond (containing-decl-open
 	       (setq placeholder (c-add-class-syntax 'inclass
diff -r 03dea479cb53 cc-langs.el
--- a/cc-langs.el	Tue Jan 12 17:50:29 2016 +0000
+++ b/cc-langs.el	Wed Jan 13 22:26:10 2016 +0000
@@ -1884,7 +1884,7 @@
 	 "bindsTo" "delegatesTo" "implements" "proxy" "storedOn")
   ;; Note: "const" is not used in Java, but it's still a reserved keyword.
   java '("abstract" "const" "final" "native" "private" "protected" "public"
-	 "static" "strictfp" "synchronized" "transient" "volatile")
+	 "default" "static" "strictfp" "synchronized" "transient" "volatile")
   pike '("final" "inline" "local" "nomask" "optional" "private" "protected"
 	 "public" "static" "variant"))
 


[ .... ]

-- 
Alan Mackenzie (Nuremberg, Germany).

bug#22358: 24.5; Analysis and indentation of Java default interface methods incorrect

[Alan Mackenzie]

Hello again, Lanning.

On Wed, Jan 13, 2016 at 04:42:34PM -0800, Lanning wrote:
> Yep, that fixes it. Thanks, and esp for the quick turn-around.

OK, I've fixed the problem in savannah, so I'm closing this bug.

> By "complicated" I mean that there are a lot of connections between things.
> Not being familiar with the code, with all the languages supported, and so
> on, I have to assume that a small change may have large consequences.

> Anyway... I've got a fix for you. The problem has to do with indentation of
> multi-line Java annotations. More accurately, the indentation of the next
> line after a multi-line annotation. Here's an example that illustrates the
> problem. The annotations should all be aligned, and the method should line
> up with the all of them.

> public class Foo {
>     @AnAnnotation("hello")
>     @AnotherAnnotation(list = { "one", "two",
>                                 "three", "four" },
>         value = "something")
>     @YetAnother
>     @AndYetAnother(
>         a = b,
>         c = d
>     )
>     @DieAnotherDay("you bet")
>     public void run() {
>     }

> } // Foo

> The problem is that the subsequent line is indented relative to the
> previous *line*, not the previous "expression".

You may not believe this, but this bug was fixed (for the upcoming 25.1
release) on 12th January, the day before you sent me your last post.
The solution implemented is for the anchor point to be at the
indentation of the line containing the start of the previous annotation.
If you'd like, I can send you a patch based on Emacs 24.5.

-- 
Alan Mackenzie (Nuremberg, Germany).