Allow compilation during loading of Modes derived from a CC Mode mode.

Fixes debbugs#19206.

cc-bytecomp.el (cc-bytecomp-compiling-or-loading): new function which
walks the stack to discover whether we're compiling or loading.
(cc-bytecomp-is-compiling): Reformulate, and move towards beginning.
(cc-bytecomp-is-loading): New defsubst.
(cc-bytecomp-setup-environment, cc-bytecomp-restore-environment): Use
the
above defsubsts.
(cc-require-when-compile, cc-bytecomp-defvar)
(cc-bytecomp-defun): Simplify conditionals.

cc-defs.el (cc-bytecomp-compiling-or-loading): "Borrow" this function
from cc-bytecomp.el.
(c-get-current-file): Reformulate using the above.
(c-lang-defconst): Prevent duplicate entries of file names in a symbol's
'source property.
(c-lang-const): Use cc-bytecomp-is-compiling.

cc-langs.el (c-make-init-lang-vars-fun): Use cc-bytecomp-is-compiling.

1 files changed, 55 insertions, 17 deletions

diff --git a/lisp/progmodes/cc-bytecomp.el b/lisp/progmodes/cc-bytecomp.el
index bf7803c85ca..b63eeb4c7a6 100644
--- a/lisp/progmodes/cc-bytecomp.el
+++ b/lisp/progmodes/cc-bytecomp.el
@@ -89,13 +89,60 @@
   ;;`(message ,@args)
   )
 
+(defun cc-bytecomp-compiling-or-loading ()
+  ;; Determine whether byte-compilation or loading is currently active,
+  ;; returning 'compiling, 'loading or nil.
+  ;; If both are active, the "innermost" activity counts.  Note that
+  ;; compilation can trigger loading (various `require' type forms)
+  ;; and loading can trigger compilation (the package manager does
+  ;; this).  We walk the lisp stack if necessary.
+  (cond
+   ((and load-in-progress
+	 (boundp 'byte-compile-dest-file)
+	 (stringp byte-compile-dest-file))
+    (let ((n 0) elt)
+      (while (and
+	      (setq elt (backtrace-frame n))
+	      (not (and (car elt)
+			(memq (cadr elt)
+			      '(load require
+				byte-compile-file byte-recompile-directory
+				batch-byte-compile)))))
+	(setq n (1+ n)))
+      (cond
+       ((memq (cadr elt) '(load require))
+	'loading)
+       ((memq (cadr elt) '(byte-compile-file
+			   byte-recompile-directory
+			   batch-byte-compile))
+	'compiling)
+       (t				; Can't happen.
+	(message "cc-bytecomp-compiling-or-loading: System flags spuriously set")
+	nil))))
+   (load-in-progress
+    ;; Being loaded.
+    'loading)
+   ((and (boundp 'byte-compile-dest-file)
+	 (stringp byte-compile-dest-file))
+    ;; Being compiled.
+    'compiling)
+   (t
+    ;; Being evaluated interactively.
+    nil)))
+
+(defsubst cc-bytecomp-is-compiling ()
+  "Return non-nil if eval'ed during compilation."
+  (eq (cc-bytecomp-compiling-or-loading) 'compiling))
+
+(defsubst cc-bytecomp-is-loading ()
+  "Return non-nil if eval'ed during loading.
+Nil will be returned if we're in a compilation triggered by the loading."
+  (eq (cc-bytecomp-compiling-or-loading) 'loading))
+
 (defun cc-bytecomp-setup-environment ()
   ;; Eval'ed during compilation to setup variables, functions etc
   ;; declared with `cc-bytecomp-defvar' et al.
-  (if (not load-in-progress)
-      ;; Look at `load-in-progress' to tell whether we're called
-      ;; directly in the file being compiled or just from some file
-      ;; being loaded during compilation.
+  (if (not (cc-bytecomp-is-loading))
       (let (p)
 	(if cc-bytecomp-environment-set
 	    (error "Byte compilation environment already set - \
@@ -143,7 +190,7 @@ perhaps a `cc-bytecomp-restore-environment' is forgotten somewhere"))
 (defun cc-bytecomp-restore-environment ()
   ;; Eval'ed during compilation to restore variables, functions etc
   ;; declared with `cc-bytecomp-defvar' et al.
-  (if (not load-in-progress)
+  (if (not (cc-bytecomp-is-loading))
       (let (p)
 	(setq p cc-bytecomp-unbound-variables)
 	(while p
@@ -287,8 +334,7 @@ use within `eval-when-compile'."
   `(eval-when-compile
      (if (and (fboundp 'cc-bytecomp-is-compiling)
 	      (cc-bytecomp-is-compiling))
-	 (if (or (not load-in-progress)
-		 (not (featurep ,cc-part)))
+	 (if (not (featurep ,cc-part))
 	     (cc-bytecomp-load (symbol-name ,cc-part)))
        (require ,cc-part))))
 
@@ -301,12 +347,6 @@ afterwards.  Don't use within `eval-when-compile'."
      (require ,feature)
      (eval-when-compile (cc-bytecomp-setup-environment))))
 
-(defun cc-bytecomp-is-compiling ()
-  "Return non-nil if eval'ed during compilation.  Don't use outside
-`eval-when-compile'."
-  (and (boundp 'byte-compile-dest-file)
-       (stringp byte-compile-dest-file)))
-
 (defmacro cc-bytecomp-defvar (var)
   "Binds the symbol as a variable during compilation of the file,
 to silence the byte compiler.  Don't use within `eval-when-compile'."
@@ -320,8 +360,7 @@ to silence the byte compiler.  Don't use within `eval-when-compile'."
 	      "cc-bytecomp-defvar: Saving %s (as unbound)" ',var)
 	     (setq cc-bytecomp-unbound-variables
 		   (cons ',var cc-bytecomp-unbound-variables))))
-       (if (and (cc-bytecomp-is-compiling)
-		(not load-in-progress))
+       (if (cc-bytecomp-is-compiling)
 	   (progn
 	     (defvar ,var)
 	     (set ',var (intern (concat "cc-bytecomp-ignore-var:"
@@ -349,8 +388,7 @@ at compile time, e.g. for macros and inline functions."
 	     (setq cc-bytecomp-original-functions
 		   (cons (list ',fun nil 'unbound)
 			 cc-bytecomp-original-functions))))
-       (if (and (cc-bytecomp-is-compiling)
-		(not load-in-progress))
+       (if (cc-bytecomp-is-compiling)
 	   (progn
 	     (fset ',fun (intern (concat "cc-bytecomp-ignore-fun:"
 					 (symbol-name ',fun))))