gitk: Show local changes properly when we have a path limit

Since gitk looks for the HEAD commit to attach the fake commits for
local changes to, we can miss out on seeing the fake commits if we
have a path limit and the HEAD commit doesn't alter any of the files
in the path limit.

This fixes it by running

	git rev-list -1 $head -- $paths

if we have a path limit, and taking the result of that as the commit
to attach the fake commits to.  This means that we can be attaching
the fake commits to a different commit in each view, so we use a new
$viewmainhead($view) for that.

This also fixes a buglet where updatecommits would only fix up the
fake commits if the HEAD changed since the last call to updatecommits,
whereas it should fix them up if the HEAD has changed since this view
was last created or updated.

Signed-off-by: Paul Mackerras <paulus@samba.org>

gitk

@@ -309,7 +309,7 @@ proc start_rev_list {view} {
     global viewargs viewargscmd viewfiles vfilelimit
     global showlocalchanges
     global viewactive viewinstances vmergeonly
-    global mainheadid
+    global mainheadid viewmainheadid viewmainheadid_orig
     global vcanopt vflags vrevs vorigargs
 
     set startmsecs [clock clicks -milliseconds]
@@ -367,8 +367,13 @@ proc start_rev_list {view} {
     }
     set i [reg_instance $fd]
     set viewinstances($view) [list $i]
-    if {$showlocalchanges && $mainheadid ne {}} {
-	interestedin $mainheadid dodiffindex
+    set viewmainheadid($view) $mainheadid
+    set viewmainheadid_orig($view) $mainheadid
+    if {$files ne {} && $mainheadid ne {}} {
+	get_viewmainhead $view
+    }
+    if {$showlocalchanges && $viewmainheadid($view) ne {}} {
+	interestedin $viewmainheadid($view) dodiffindex
     }
     fconfigure $fd -blocking 0 -translation lf -eofchar {}
     if {$tclencoding != {}} {
@@ -446,22 +451,26 @@ proc updatecommits {} {
     global curview vcanopt vorigargs vfilelimit viewinstances
     global viewactive viewcomplete tclencoding
     global startmsecs showneartags showlocalchanges
-    global mainheadid pending_select
+    global mainheadid viewmainheadid viewmainheadid_orig pending_select
     global isworktree
     global varcid vposids vnegids vflags vrevs
 
     set isworktree [expr {[exec git rev-parse --is-inside-work-tree] == "true"}]
-    set oldmainid $mainheadid
     rereadrefs
-    if {$showlocalchanges} {
-	if {$mainheadid ne $oldmainid} {
+    set view $curview
+    if {$mainheadid ne $viewmainheadid_orig($view)} {
+	if {$showlocalchanges} {
 	    dohidelocalchanges
 	}
-	if {[commitinview $mainheadid $curview]} {
-	    dodiffindex
+	set viewmainheadid($view) $mainheadid
+	set viewmainheadid_orig($view) $mainheadid
+	if {$vfilelimit($view) ne {}} {
+	    get_viewmainhead $view
 	}
     }
-    set view $curview
+    if {$showlocalchanges} {
+	doshowlocalchanges
+    }
     if {$vcanopt($view)} {
 	set oldpos $vposids($view)
 	set oldneg $vnegids($view)
@@ -4643,14 +4652,56 @@ proc layoutmore {} {
     drawvisible
 }
 
+# With path limiting, we mightn't get the actual HEAD commit,
+# so ask git rev-list what is the first ancestor of HEAD that
+# touches a file in the path limit.
+proc get_viewmainhead {view} {
+    global viewmainheadid vfilelimit viewinstances mainheadid
+
+    catch {
+	set rfd [open [concat | git rev-list -1 $mainheadid \
+			   -- $vfilelimit($view)] r]
+	set j [reg_instance $rfd]
+	lappend viewinstances($view) $j
+	fconfigure $rfd -blocking 0
+	filerun $rfd [list getviewhead $rfd $j $view]
+	set viewmainheadid($curview) {}
+    }
+}
+
+# git rev-list should give us just 1 line to use as viewmainheadid($view)
+proc getviewhead {fd inst view} {
+    global viewmainheadid commfd curview viewinstances showlocalchanges
+
+    set id {}
+    if {[gets $fd line] < 0} {
+	if {![eof $fd]} {
+	    return 1
+	}
+    } elseif {[string length $line] == 40 && [string is xdigit $line]} {
+	set id $line
+    }
+    set viewmainheadid($view) $id
+    close $fd
+    unset commfd($inst)
+    set i [lsearch -exact $viewinstances($view) $inst]
+    if {$i >= 0} {
+	set viewinstances($view) [lreplace $viewinstances($view) $i $i]
+    }
+    if {$showlocalchanges && $id ne {} && $view == $curview} {
+	doshowlocalchanges
+    }
+    return 0
+}
+
 proc doshowlocalchanges {} {
-    global curview mainheadid
+    global curview viewmainheadid
 
-    if {$mainheadid eq {}} return
-    if {[commitinview $mainheadid $curview]} {
+    if {$viewmainheadid($curview) eq {}} return
+    if {[commitinview $viewmainheadid($curview) $curview]} {
 	dodiffindex
     } else {
-	interestedin $mainheadid dodiffindex
+	interestedin $viewmainheadid($curview) dodiffindex
     }
 }
 
@@ -4668,19 +4719,24 @@ proc dohidelocalchanges {} {
 
 # spawn off a process to do git diff-index --cached HEAD
 proc dodiffindex {} {
-    global lserial showlocalchanges
+    global lserial showlocalchanges vfilelimit curview
     global isworktree
 
     if {!$showlocalchanges || !$isworktree} return
     incr lserial
-    set fd [open "|git diff-index --cached HEAD" r]
+    set cmd "|git diff-index --cached HEAD"
+    if {$vfilelimit($curview) ne {}} {
+	set cmd [concat $cmd -- $vfilelimit($curview)]
+    }
+    set fd [open $cmd r]
     fconfigure $fd -blocking 0
     set i [reg_instance $fd]
     filerun $fd [list readdiffindex $fd $lserial $i]
 }
 
 proc readdiffindex {fd serial inst} {
-    global mainheadid nullid nullid2 curview commitinfo commitdata lserial
+    global viewmainheadid nullid nullid2 curview commitinfo commitdata lserial
+    global vfilelimit
 
     set isdiff 1
     if {[gets $fd line] < 0} {
@@ -4697,7 +4753,11 @@ proc readdiffindex {fd serial inst} {
     }
 
     # now see if there are any local changes not checked in to the index
-    set fd [open "|git diff-files" r]
+    set cmd "|git diff-files"
+    if {$vfilelimit($curview) ne {}} {
+	set cmd [concat $cmd -- $vfilelimit($curview)]
+    }
+    set fd [open $cmd r]
     fconfigure $fd -blocking 0
     set i [reg_instance $fd]
     filerun $fd [list readdifffiles $fd $serial $i]
@@ -4710,15 +4770,18 @@ proc readdiffindex {fd serial inst} {
 	if {[commitinview $nullid $curview]} {
 	    removefakerow $nullid
 	}
-	insertfakerow $nullid2 $mainheadid
+	insertfakerow $nullid2 $viewmainheadid($curview)
     } elseif {!$isdiff && [commitinview $nullid2 $curview]} {
+	if {[commitinview $nullid $curview]} {
+	    removefakerow $nullid
+	}
 	removefakerow $nullid2
     }
     return 0
 }
 
 proc readdifffiles {fd serial inst} {
-    global mainheadid nullid nullid2 curview
+    global viewmainheadid nullid nullid2 curview
     global commitinfo commitdata lserial
 
     set isdiff 1
@@ -4743,7 +4806,7 @@ proc readdifffiles {fd serial inst} {
 	if {[commitinview $nullid2 $curview]} {
 	    set p $nullid2
 	} else {
-	    set p $mainheadid
+	    set p $viewmainheadid($curview)
 	}
 	insertfakerow $nullid $p
     } elseif {!$isdiff && [commitinview $nullid $curview]} {
@@ -8341,6 +8404,7 @@ proc cherrypick {} {
     }
     addnewchild $newhead $oldhead
     if {[commitinview $oldhead $curview]} {
+	# XXX this isn't right if we have a path limit...
 	insertrow $newhead $oldhead $curview
 	if {$mainhead ne {}} {
 	    movehead $newhead $mainhead
@@ -8448,7 +8512,7 @@ proc headmenu {x y id head} {
 
 proc cobranch {} {
     global headmenuid headmenuhead headids
-    global showlocalchanges mainheadid
+    global showlocalchanges
 
     # check the tree is clean first??
     nowbusy checkout [mc "Checking out"]
@@ -8469,6 +8533,7 @@ proc cobranch {} {
 
 proc readcheckoutstat {fd newhead newheadid} {
     global mainhead mainheadid headids showlocalchanges progresscoords
+    global viewmainheadid curview
 
     if {[gets $fd line] >= 0} {
 	if {[regexp {([0-9]+)% \(([0-9]+)/([0-9]+)\)} $line match p m n]} {
@@ -8486,6 +8551,7 @@ proc readcheckoutstat {fd newhead newheadid} {
     set oldmainid $mainheadid
     set mainhead $newhead
     set mainheadid $newheadid
+    set viewmainheadid($curview) $newheadid
     redrawtags $oldmainid
     redrawtags $newheadid
     selbyid $newheadid