match: do not weirdly include explicit files excluded by -X option

match: do not weirdly include explicit files excluded by -X option

Actually, this was the original behavior. Before a83a7d27911e, "log" and
"files" showed nothing if "FILE -X FILE" was specified, whereas "debugwalk"
got confused by an explicit FILE pattern. Under the hood, "log" and "files"
use m() and ctx.matches(m) respectively, and "debugwalk" uses ctx.walk(m).
I suspect dirstate.walk() goes wrong in _walkexplicit(), which seems to
blindly trust m.files().

I reckon the original "log"/"files" behavior is correct, and drop the hack
from the differencematcher.

--- a/mercurial/match.py	Sun Jan 14 15:56:22 2018 -0500
+++ b/mercurial/match.py	Tue Jan 16 22:14:33 2018 +0900
@@ -457,17 +457,10 @@
 
 class differencematcher(basematcher):
     '''Composes two matchers by matching if the first matches and the second
-    does not. Well, almost... If the user provides a pattern like "-X foo foo",
-    Mercurial actually does match "foo" against that. That's because exact
-    matches are treated specially. So, since this differencematcher is used for
-    excludes, it needs to special-case exact matching.
+    does not.
 
     The second matcher's non-matching-attributes (root, cwd, bad, explicitdir,
     traversedir) are ignored.
-
-    TODO: If we want to keep the behavior described above for exact matches, we
-    should consider instead treating the above case something like this:
-    union(exact(foo), difference(pattern(foo), include(foo)))
     '''
     def __init__(self, m1, m2):
         super(differencematcher, self).__init__(m1._root, m1._cwd)
@@ -478,7 +471,7 @@
         self.traversedir = m1.traversedir
 
     def matchfn(self, f):
-        return self._m1(f) and (not self._m2(f) or self._m1.exact(f))
+        return self._m1(f) and not self._m2(f)
 
     @propertycache
     def _files(self):
@@ -493,9 +486,6 @@
 
     def visitdir(self, dir):
         if self._m2.visitdir(dir) == 'all':
-            # There's a bug here: If m1 matches file 'dir/file' and m2 excludes
-            # 'dir' (recursively), we should still visit 'dir' due to the
-            # exception we have for exact matches.
             return False
         return bool(self._m1.visitdir(dir))
 

--- a/tests/test-locate.t	Sun Jan 14 15:56:22 2018 -0500
+++ b/tests/test-locate.t	Tue Jan 16 22:14:33 2018 +0900
@@ -103,6 +103,11 @@
   $ hg files b
   b
 
+-X with explicit path:
+
+  $ hg files b -X b
+  [1]
+
   $ mkdir otherdir
   $ cd otherdir
 

--- a/tests/test-log.t	Sun Jan 14 15:56:22 2018 -0500
+++ b/tests/test-log.t	Tue Jan 16 22:14:33 2018 +0900
@@ -102,6 +102,10 @@
   summary:     c
   
 
+-X, with explicit path
+
+  $ hg log a -X a
+
 -f, non-existent directory
 
   $ hg log -f dir

--- a/tests/test-walk.t	Sun Jan 14 15:56:22 2018 -0500
+++ b/tests/test-walk.t	Tue Jan 16 22:14:33 2018 +0900
@@ -344,6 +344,21 @@
   abort: path 'beans/.hg' is inside nested repo 'beans'
   [255]
 
+Test explicit paths and excludes:
+(BROKEN: nothing should be included, but wctx.walk() does)
+
+  $ hg debugwalk fennel -X fennel
+  matcher: <differencematcher m1=<patternmatcher patterns='(?:fennel(?:/|$))'>, m2=<includematcher includes='(?:fennel(?:/|$))'>>
+  f  fennel  fennel  exact
+  $ hg debugwalk fennel -X 'f*'
+  matcher: <differencematcher m1=<patternmatcher patterns='(?:fennel(?:/|$))'>, m2=<includematcher includes='(?:f[^/]*(?:/|$))'>>
+  f  fennel  fennel  exact
+  $ hg debugwalk beans/black -X 'path:beans'
+  matcher: <differencematcher m1=<patternmatcher patterns='(?:beans\\/black(?:/|$))'>, m2=<includematcher includes='(?:beans(?:/|$))'>>
+  f  beans/black  beans/black  exact
+  $ hg debugwalk -I 'path:beans/black' -X 'path:beans'
+  matcher: <differencematcher m1=<includematcher includes='(?:beans\\/black(?:/|$))'>, m2=<includematcher includes='(?:beans(?:/|$))'>>
+
 Test absolute paths:
 
   $ hg debugwalk `pwd`/beans