From: Ian Jackson <ijackson@chiark.greenend.org.uk>
Date: Wed, 8 Feb 2012 18:01:24 +0000 (+0000)
Subject: Unwanted dep removal search - difficulties
X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ian/git?p=topbloke.git;a=commitdiff_plain;h=9a8795b9394e4064ebe309bedf0162c193922952;ds=sidebyside

Unwanted dep removal search - difficulties
---

diff --git a/DESIGN b/DESIGN
index 1569517..97f0681 100644
--- a/DESIGN
+++ b/DESIGN
@@ -280,41 +280,64 @@ rm..  rm..
 
 
 
-               	       	        proposed               	       (elsewhere)
-                              /          \             	   |   |
-	                     /            \                |   |
-                            /              |           	   |   |
-	           REMOVAL rm              |           	   |   |
-	                   |               |           	   |   |
-	                 inc               |           	   |   |
-       	                 / |               |           	   |   |
-	                /  inc             |           	   |   |
-	               |   | `------------ | ----<-------- | -.|
-       	              inc  inc             |           	   |   *2
-	               |`- | ------------- | ----<--------.|   |
-	               `---inc             |           	  1*  /
- 	                   |               |           	   | /
- 	        RE-INCLUDE inc             rm REMOVAL  	   |'
-   	        \          |              /            	   |
-    	         * REMOVAL rm            /             	   |
-       	                   |           inc             	   |
- 	                   inc         /               	   |
- 	                   |          /                	   |
- 	                   inc       /                 	   |
- 	                   |        /`--------<-----------.|
- 	                   inc     /                   	   |
- 	                   |      /                    	   |
- 	        RE-INCLUDE inc   /                     	   |
-       	        \          |    /                      	   |
- 	         * REMOVAL rm  /                       	   |
-                           |  /                        	   |
-                           inc 		       	       	   |
-		 	      \		       	       	   |
-		 	       `------------<-------------.|
-		 				       	   |
-		 				    	   |
-		 				       	  IT
+          OUR BASE              SOURCE		       OUR IT TIP
+		| 	       	   |			   |
+		| 	           | 			   |
+   ADD DEP WH/ inc	       	   rm			   |
+    NEEDS IT   /|	       	   /\			   |
+	      /	| 	       	 rm  \			   |
+	     /	| ______________'/    \			   |
+	  inc	|'	       	/      \		   |   	 IT tip
+           /   inc     REMOVAL rm       \              	   |   	elsewhere
+          /     |             /          \             	   |   |   |
+	 /      |           inc           \                |   |   |
+     some IT    |           /              |           	   |   |   |
+                |         inc              |           	   |   |   |
+               /           |               |           	   |   |   |
+              /          inc               |           	   |   |   |
+             |           / |               |           	   |   |   |
+	    /           /  inc             |           	   |   |   |
+	   /           |   | `------------ | ----<-------- | -.|   |
+       	  /           inc  inc             |           	   |   *2  |
+	  |            |`- | ------------- | ----<--------.|   |   |
+	  |            `---inc             |           	  1*  /	   |
+ 	  |                |               |           	   | /	   |
+ 	  |     RE-INCLUDE inc             rm REMOVAL  	   |'	   |
+        inc     \          |               |           	   |	   |
+    	  |      * REMOVAL rm              |           	   |	   |
+       	  |                |              /            	   |	   |
+       	  |`-------------- | ----------. /             	   |	   |
+       	  |                |           inc ANC2        	   |	   |
+ 	 inc               inc         /               	   |	   |
+ 	  |`.____________  |          /                	   |	   |
+ 	  |              `inc ANC1   /                 	   |	   |
+ 	  |                |        /`--------<----------- | ---.  |
+ 	without            inc     /                   	   |	 \/
+ 	  |                |      /                    	   |	 /
+ 	   \    RE-INCLUDE inc   /                     	   |   	/
+       	    \   \          |    /                      	   |   /
+ 	     \   * REMOVAL rm  /                       	   |  /
+              \            |  /                        	   | /
+               \           inc FIRST ADD DEP   	       	   |/
+		\	   |  \	       	       	       	   *3
+		 \	   |   `------------<-------------.|
+       	       	  \    	   | 	      		       	   |
+ 		   \	   without    		       	   |
+		    \_____ |   	      		       	   |
+		 	  `without    		       	   |
+		 	   |   	      		    	   |
+		 		      		       	  IT
 
 
   Merge 1* and 2*, diff against some relevant base branch commit
-  or something, and apply to proposed.
+  or something, and apply to proposed. ???
+
+
+After we are done:
+  source tip is included in our base
+
+Each time:
+  * pick common ancestor
+  * compute whether merge from common anc would unwantedly remove
+  * if so we arrange that the common anc is a "rm" but our branch
+    actually contains IT