Flymake highlights GCC info/notes as detected by flymake-proc.el

* lisp/progmodes/flymake-proc.el
(flymake-proc--diagnostics-for-pattern): Rewrite (using cl-loop) to
honour more sophisticated flymake-proc-diagnostic-type-pred.
(flymake-warning-re): Is now an obsolete alias for
flymake-proc-diagnostic-type-pred.
(flymake-proc-diagnostic-type-pred): Rename and augment from
flymake-proc-warning-predicate.  (flymake-proc-warning-predicate):
Delete.

* lisp/progmodes/flymake.el (flymake-note): New face.
(flymake-diagnostic-types-alist): Simplify.
(flymake-note): New overlay category.
(flymake--lookup-type-property): Only lookup single keys, not lists.
(flymake--diag-errorp): Rewrite.
(flymake--highlight-line): Use flymake--lookup-type-property.

* test/lisp/progmodes/flymake-tests.el
(different-diagnostic-types): Rename from errors-and-warnings.
Check notes.
(flymake-tests--call-with-fixture): Use
flymake-proc-diagnostic-type-pred.

2 files changed, 86 insertions, 67 deletions

diff --git a/lisp/progmodes/flymake-proc.el b/lisp/progmodes/flymake-proc.el
index dd6bf501733..2e593bd758d 100644
--- a/lisp/progmodes/flymake-proc.el
+++ b/lisp/progmodes/flymake-proc.el
@@ -394,47 +394,51 @@ Create parent directories as needed."
   (flymake-log 3 "saved buffer %s in file %s" (buffer-name) file-name))
 
 (defun flymake-proc--diagnostics-for-pattern (proc pattern)
-  (condition-case err
-      (pcase-let ((`(,regexp ,file-idx ,line-idx ,col-idx ,message-idx)
-                   pattern)
-                  (retval))
-        (while (search-forward-regexp regexp nil t)
-          (let* ((fname (and file-idx (match-string file-idx)))
-                 (message (and message-idx (match-string message-idx)))
-                 (line-string (and line-idx (match-string line-idx)))
-                 (line-number (and line-string
-                                   (string-to-number line-string)))
-                 (col-string (and col-idx (match-string col-idx)))
-                 (col-number (and col-string
-                                  (string-to-number col-string))))
-            (with-current-buffer (process-buffer proc)
-              (push
-               (flymake-make-diagnostic
-                :file fname
-                :line line-number
-                :col col-number
-                :type (if (and
-                           message
-                           (cond ((stringp flymake-proc-warning-predicate)
-                                  (string-match flymake-proc-warning-predicate
-                                                message))
-                                 ((functionp flymake-proc-warning-predicate)
-                                  (funcall flymake-proc-warning-predicate
-                                           message))))
-                          "w"
-                        "e")
-                :text message
-                :full-file (and fname
-                                (funcall
-                                 (flymake-proc--get-real-file-name-function
-                                  fname)
-                                 fname)))
-               retval))))
-        retval)
-    (error
-     (flymake-log 1 "Error parsing process output for pattern %s: %s"
-                  pattern err)
-     nil)))
+  (cl-flet ((guess-type
+             (pred message)
+             (cond ((null message)
+                    :error)
+                   ((stringp pred)
+                    (if (string-match pred message)
+                        :warning
+                      :error))
+                   ((functionp pred)
+                    (let ((probe (funcall pred message)))
+                      (cond ((assoc-default probe
+                                            flymake-diagnostic-types-alist)
+                             probe)
+                            (probe
+                             :warning)
+                            (t
+                             :error)))))))
+    (condition-case err
+        (cl-loop
+         with (regexp file-idx line-idx col-idx message-idx) = pattern
+         while (search-forward-regexp regexp nil t)
+         for fname = (and file-idx (match-string file-idx))
+         for message = (and message-idx (match-string message-idx))
+         for line-string = (and line-idx (match-string line-idx))
+         for line-number = (and line-string
+                                (string-to-number line-string))
+         for col-string = (and col-idx (match-string col-idx))
+         for col-number = (and col-string
+                               (string-to-number col-string))
+         collect (with-current-buffer (process-buffer proc)
+                   (flymake-make-diagnostic
+                    :file fname
+                    :line line-number
+                    :col col-number
+                    :type (guess-type flymake-proc-diagnostic-type-pred message)
+                    :text message
+                    :full-file (and fname
+                                    (funcall
+                                     (flymake-proc--get-real-file-name-function
+                                      fname)
+                                     fname)))))
+      (error
+       (flymake-log 1 "Error parsing process output for pattern %s: %s"
+                    pattern err)
+       nil))))
 
 (defun flymake-proc--process-filter (proc string)
   "Parse STRING and collect diagnostics info."
@@ -567,12 +571,29 @@ Convert it to flymake internal format."
 Use `flymake-proc-reformat-err-line-patterns-from-compile-el' to add patterns
 from compile.el")
 
-(define-obsolete-variable-alias 'flymake-warning-re 'flymake-proc-warning-predicate "24.4")
-(defvar flymake-proc-warning-predicate "^[wW]arning"
-  "Predicate matching against error text to detect a warning.
-Takes a single argument, the error's text and should return non-nil
-if it's a warning.
-Instead of a function, it can also be a regular expression.")
+(define-obsolete-variable-alias 'flymake-warning-re 'flymake-proc-diagnostic-type-pred "26.1")
+(defvar flymake-proc-diagnostic-type-pred
+  'flymake-proc-default-guess
+  "Predicate matching against diagnostic text to detect its type.
+Takes a single argument, the diagnostic's text and should return
+a value suitable for indexing
+`flymake-diagnostic-types-alist' (which see). If the returned
+value is nil, a type of `error' is assumed. For some backward
+compatibility, if a non-nil value is returned that that doesn't
+index that alist, a type of `:warning' is assumed.
+
+Instead of a function, it can also be a string, a regular
+expression. A match indicates `:warning' type, otherwise
+`:error'")
+
+(defun flymake-proc-default-guess (text)
+  "Guess if TEXT means a warning, a note or an error."
+  (cond ((string-match "^[wW]arning" text)
+         :warning)
+        ((string-match "^[nN]ote" text)
+         :note)
+        (t
+         :error)))
 
 (defun flymake-proc-get-project-include-dirs-imp (basedir)
   "Include dirs for the project current file belongs to."
@@ -1167,12 +1188,6 @@ Convert it to flymake internal format.")
 (REGEXP FILE-IDX LINE-IDX COL-IDX ERR-TEXT-IDX).
 Use `flymake-reformat-err-line-patterns-from-compile-el' to add patterns
 from compile.el")
-  (define-obsolete-variable-alias 'flymake-warning-predicate
-    'flymake-proc-warning-predicate "26.1"
-    "Predicate matching against error text to detect a warning.
-Takes a single argument, the error's text and should return non-nil
-if it's a warning.
-Instead of a function, it can also be a regular expression.")
   (define-obsolete-function-alias 'flymake-parse-line
     'flymake-proc-parse-line "26.1"
     "Parse LINE to see if it is an error or warning.
diff --git a/lisp/progmodes/flymake.el b/lisp/progmodes/flymake.el
index 827bce4b634..b32e799e672 100644
--- a/lisp/progmodes/flymake.el
+++ b/lisp/progmodes/flymake.el
@@ -189,6 +189,15 @@ verify FILTER, sort them by COMPARE (using KEY)."
   :version "24.4"
   :group 'flymake)
 
+(defface flymake-note
+  '((((supports :underline (:style wave)))
+     :underline (:style wave :color "yellow green"))
+    (t
+     :inherit warning))
+  "Face used for marking note regions."
+  :version "26.1"
+  :group 'flymake)
+
 (define-obsolete-face-alias 'flymake-warnline 'flymake-warning "26.1")
 (define-obsolete-face-alias 'flymake-errline 'flymake-error "26.1")
 
@@ -226,13 +235,14 @@ Or nil if the region is invalid."
            nil)))
 
 (defvar flymake-diagnostic-types-alist
-  `((("e" :error error)
+  `((:error
      . ((flymake-category . flymake-error)))
-    (("w" :warning warning)
-     . ((flymake-category . flymake-warning))))
+    (:warning
+     . ((flymake-category . flymake-warning)))
+    (:note
+     . ((flymake-category . flymake-note))))
   "Alist ((KEY . PROPS)*) of properties of flymake error types.
-KEY can be anything passed as `:type' to `flymake-diag-make', or
-a list of these objects.
+KEY can be anything passed as `:type' to `flymake-diag-make'.
 
 PROPS is an alist of properties that are applied, in order, to
 the diagnostics of each type.  The recognized properties are:
@@ -259,27 +269,21 @@ the diagnostics of each type.  The recognized properties are:
 (put 'flymake-error 'face 'flymake-error)
 (put 'flymake-error 'bitmap flymake-error-bitmap)
 (put 'flymake-error 'severity (warning-numeric-level :error))
-(put 'flymake-error 'mode-line-face 'compilation-error)
 
 (put 'flymake-warning 'face 'flymake-warning)
 (put 'flymake-warning 'bitmap flymake-warning-bitmap)
 (put 'flymake-warning 'severity (warning-numeric-level :warning))
-(put 'flymake-warning 'mode-line-face 'compilation-warning)
 
 (put 'flymake-note 'face 'flymake-note)
 (put 'flymake-note 'bitmap flymake-warning-bitmap)
 (put 'flymake-note 'severity (warning-numeric-level :debug))
-(put 'flymake-note 'mode-line-face 'compilation-info)
 
 (defun flymake--lookup-type-property (type prop &optional default)
   "Look up PROP for TYPE in `flymake-diagnostic-types-alist'.
 If TYPE doesn't declare PROP in either
-`flymake-diagnostic-types-alist' or its associated category,
-return DEFAULT."
-  (let ((alist-probe (assoc type flymake-diagnostic-types-alist
-                            (lambda (entry key)
-                              (or (equal key entry)
-                                  (member key entry))))))
+`flymake-diagnostic-types-alist' or its associated
+`flymake-category', return DEFAULT."
+  (let ((alist-probe (assoc type flymake-diagnostic-types-alist)))
     (cond (alist-probe
            (let* ((alist (cdr alist-probe))
                   (prop-probe (assoc prop alist)))