Review request: javac in compilation-error-regexp-alist-alist

[Filipp Gunbin <fgunbin@fastmail.fm>]

Hi, I've made an attempt to teach compilation-parse-errors to handle
javac output.

We don't have column number there in the compiler output, and it's very
inconvenient, so I'm deducing it from where the visual pointer ("^")
points.

Is this approach fine, or too dirty to be committed?

BTW I fixed a small bug where we check whether file/line/col is consp,
and at the same time allow it to be function, so lambda/closure will
erroneously match.

Besides that, `java' symbol in the said list is a misnomer: it handles
java exceptions (why? we would never normally have them in the
compilation output), and valgrind output.  Looks like we should just
rename it to `valgrind'.

Thanks,
Filipp


diff --git a/etc/compilation.txt b/etc/compilation.txt
index ebce6a14d0..ed2eecd778 100644
--- a/etc/compilation.txt
+++ b/etc/compilation.txt
@@ -237,6 +237,19 @@ Register 6 contains wrong type
 ==1332==    by 0x8008621: main (vtest.c:180)
 
 
+* javac Java compiler
+
+symbol: javac
+
+Should also work when compiling Java with Gradle.  We don't have
+column number, but we try to deduce it from position of "^".
+
+Test.java:5: error: ';' expected
+        foo foo
+               ^
+1 error
+
+
 * IBM jikes
 
 symbols: jikes-file jikes-line
diff --git a/lisp/progmodes/compile.el b/lisp/progmodes/compile.el
index 455f181f50..890b04864a 100644
--- a/lisp/progmodes/compile.el
+++ b/lisp/progmodes/compile.el
@@ -265,6 +265,23 @@ compilation-error-regexp-alist-alist
     (java
      "^\\(?:[ \t]+at \\|==[0-9]+== +\\(?:at\\|b\\(y\\)\\)\\).+(\\([^()\n]+\\):\\([0-9]+\\))$" 2 3 nil (1))
 
+    (javac
+     ,(concat
+       ;; line1
+       "^\\(\\(?:[A-Za-z]:\\)?[^:\n]+\\): *"      ;file
+       "\\([0-9]+\\): *"                          ;line
+       "\\(?:error:\\|\\(warning\\):\\)?[^\n]*\n" ;type (optional) and message
+       ;; line2: source line containing error
+       "[^\n]*\n"
+       ;; line3: single "^" under error position in line2
+       "[[:space:]]*\\^\n")
+     1 2
+     (lambda ()
+       (save-excursion
+         (backward-char 2)              ; move back over "^\n"
+         (current-column)))
+     (3))
+
     (jikes-file
      "^\\(?:Found\\|Issued\\) .* compiling \"\\(.+\\)\":$" 1 nil nil 0)
 
@@ -1455,9 +1472,15 @@ compilation-parse-errors
         nil) ;; Not anchored or anchored but already allows empty spaces.
        (t (setq pat (concat "^\\(?:      \\)?" (substring pat 1)))))
 
-      (if (consp file)	(setq fmt (cdr file)	  file (car file)))
-      (if (consp line)	(setq end-line (cdr line) line (car line)))
-      (if (consp col)	(setq end-col (cdr col)	  col (car col)))
+      (if (and (consp file) (not (functionp file)))
+	  (setq fmt (cdr file)
+                file (car file)))
+      (if (and (consp line) (not (functionp line)))
+          (setq end-line (cdr line)
+                line (car line)))
+      (if (and (consp col) (not (functionp col)))
+          (setq end-col (cdr col)
+                col (car col)))
 
       (unless (or (null (nth 5 item)) (integerp (nth 5 item)))
         (error "HYPERLINK should be an integer: %s" (nth 5 item)))
diff --git a/test/lisp/progmodes/compile-tests.el b/test/lisp/progmodes/compile-tests.el
index 75962566f1..81452c1c38 100644
--- a/test/lisp/progmodes/compile-tests.el
+++ b/test/lisp/progmodes/compile-tests.el
@@ -176,6 +176,9 @@ compile-tests--test-regexps-data
      13 nil 217 "../src/Lib/System.cpp")
     ("==1332==    by 0x8008621: main (vtest.c:180)"
      13 nil 180 "vtest.c")
+    ;; javac
+    ("/src/Test.java:5: ';' expected\n        foo foo\n               ^\n" 1 15 5 "/src/Test.java" 2)
+    ("e:\\src\\Test.java: 7: warning: ';' expected\n   foo foo\n          ^\n" 1 10 7 "e:\\src\\Test.java" 1)
     ;; jikes-file jikes-line
     ("Found 2 semantic errors compiling \"../javax/swing/BorderFactory.java\":"
      1 nil nil "../javax/swing/BorderFactory.java")
@@ -431,8 +434,8 @@ compile-test-error-regexps
           (compilation-num-warnings-found 0)
           (compilation-num-infos-found 0))
       (mapc #'compile--test-error-line compile-tests--test-regexps-data)
-      (should (eq compilation-num-errors-found 93))
-      (should (eq compilation-num-warnings-found 36))
+      (should (eq compilation-num-errors-found 94))
+      (should (eq compilation-num-warnings-found 37))
       (should (eq compilation-num-infos-found 26)))))
 
 (ert-deftest compile-test-grep-regexps ()