Merge pull request #154 from nikomatsakis/new-errors

add code to handle new-style rustc errors

Author: MicahChalmer

rust-mode.el

@@ -1381,15 +1381,49 @@ This is written mainly to be used as `end-of-defun-function' for Rust."
   "Specifications for matching errors in rustc invocations.
 See `compilation-error-regexp-alist' for help on their format.")
 
+(defvar rustc-new-compilation-regexps
+  (let ((file "\\([^\n]+\\)")
+        (start-line "\\([0-9]+\\)")
+        (start-col  "\\([0-9]+\\)"))
+    (let ((re (concat "^ *--> " file ":" start-line ":" start-col ; --> 1:2:3
+                      )))
+      (cons re '(1 2 3))))
+  "Specifications for matching errors in rustc invocations (new style).
+See `compilation-error-regexp-alist' for help on their format.")
+
 ;; Match test run failures and panics during compilation as
 ;; compilation warnings
 (defvar cargo-compilation-regexps
   '("^\\s-+thread '[^']+' panicked at \\('[^']+', \\([^:]+\\):\\([0-9]+\\)\\)" 2 3 nil nil 1)
   "Specifications for matching panics in cargo test invocations.
 See `compilation-error-regexp-alist' for help on their format.")
 
+(defun rustc-scroll-down-after-next-error ()
+  "In the new style error messages, the regular expression
+   matches on the file name (which appears after `-->`), but the
+   start of the error appears a few lines earlier. This hook runs
+   after `M-x next-error`; it simply scrolls down a few lines in
+   the compilation window until the top of the error is visible."
+  (save-selected-window
+    (when (eq major-mode 'rust-mode)
+      (select-window (get-buffer-window next-error-last-buffer))
+      (when (save-excursion
+              (beginning-of-line)
+              (looking-at " *-->"))
+        (let ((start-of-error
+               (save-excursion
+                 (beginning-of-line)
+                 (while (not (looking-at "^[a-z]+:"))
+                   (forward-line -1))
+                 (point))))
+          (set-window-start (selected-window) start-of-error))))))
+
 (eval-after-load 'compile
   '(progn
+     (add-to-list 'compilation-error-regexp-alist-alist
+                  (cons 'rustc-new rustc-new-compilation-regexps))
+     (add-to-list 'compilation-error-regexp-alist 'rustc-new)
+     (add-hook 'next-error-hook 'rustc-scroll-down-after-next-error)
      (add-to-list 'compilation-error-regexp-alist-alist
                   (cons 'rustc rustc-compilation-regexps))
      (add-to-list 'compilation-error-regexp-alist 'rustc)