color: don't disable colors if HGPLAINEXCEPT=color

Summary:
With `HGPLAINEXCEPT=color`, colors should still be enabled if the terminal is
capable of supporting them and output is to the terminal.

Currently this doesn't work if `--color=auto` (the default), as
`color._modesetup` uses `ui.formatted` to check if the output is a terminal,
and thus has colors available, but this is `False` for all `HGPLAIN` modes.

Instead, add a new method to `ui` that checks whether  `fout` is a terminal, and
use that for color autodetection.

This function also allows us to add `HGPLAINEXCEPT=pager` as we can use
that in the same way.

Reviewed By: farnz

Differential Revision: D21617170

fbshipit-source-id: 7ee4eaa8963f3d6eb7ed8044a678a4804b9a98f0

eden/scm/edenscm/mercurial/color.py

@@ -178,14 +178,16 @@ def _modesetup(ui):
     if not always and not auto:
         return None
 
-    formatted = always or (encoding.environ.get("TERM") != "dumb" and ui.formatted)
+    havecolors = always or (
+        encoding.environ.get("TERM") != "dumb" and ui.terminaloutput()
+    )
 
     if pycompat.iswindows:
         from . import win32
 
         if not (util.istest() or win32.enablevtmode()):
             if not ui.pageractive:
-                if formatted:
+                if havecolors:
                     ui.warn(
                         _(
                             "couldn't enable VT mode for your terminal, disabling colors\n"
@@ -194,7 +196,7 @@ def _modesetup(ui):
                 if not always:
                     return None
 
-    if always or (auto and formatted):
+    if always or (auto and havecolors):
         return "ansi"
     return None
 

eden/scm/edenscm/mercurial/configitems.py

@@ -456,6 +456,7 @@ coreconfigitem("ui", "allowemptycommit", default=False)
 coreconfigitem("ui", "allowmerge", default=True)
 coreconfigitem("ui", "archivemeta", default=True)
 coreconfigitem("ui", "askusername", default=False)
+coreconfigitem("ui", "assume-tty", default=False)
 coreconfigitem("ui", "autopullcommits", default=True)
 coreconfigitem("ui", "clonebundlefallback", default=False)
 coreconfigitem("ui", "clonebundleprefers", default=list)

eden/scm/edenscm/mercurial/ui.py

@@ -180,6 +180,8 @@ class ui(object):
         # color mode: see mercurial/color.py for possible value
         self._colormode = None
         self._styles = {}
+        # Whether the output stream is known to be a terminal.
+        self._terminaloutput = None
 
         if src:
             self._uiconfig = src._uiconfig.copy()
@@ -191,6 +193,7 @@ class ui(object):
             self._disablepager = src._disablepager
             self._tweaked = src._tweaked
             self._outputui = src._outputui
+            self._terminaloutput = src._terminaloutput
 
             self.environ = src.environ
             self.callhooks = src.callhooks
@@ -755,6 +758,8 @@ class ui(object):
     def _isatty(self, fh):
         if self.configbool("ui", "nontty"):
             return False
+        if self.configbool("ui", "assume-tty"):
+            return True
         return util.isatty(fh)
 
     def disablepager(self):
@@ -783,10 +788,8 @@ class ui(object):
             command in self.configlist("pager", "ignore")
             or not self.configbool("ui", "paginate")
             or not self.configbool("pager", "attend-" + command, True)
-            # TODO: if we want to allow HGPLAINEXCEPT=pager,
-            # formatted() will need some adjustment.
-            or not self.formatted
-            or self.plain()
+            or not self.terminaloutput()
+            or self.plain("pager")
             or self._buffers
             # TODO: expose debugger-enabled on the UI object
             or "--debugger" in pycompat.sysargv
@@ -809,6 +812,7 @@ class ui(object):
         self.flush()
 
         wasformatted = self.formatted
+        wasterminaloutput = self.terminaloutput()
         if util.safehasattr(signal, "SIGPIPE"):
             signal.signal(signal.SIGPIPE, _catchterm)
         if pagercmd == "internal:streampager":
@@ -821,6 +825,7 @@ class ui(object):
             self.setconfig("ui", "formatted", wasformatted, "pager")
             util.clearcachedproperty(self, "formatted")
             self.setconfig("ui", "interactive", False, "pager")
+            self._terminaloutput = wasterminaloutput
 
             # If pager encoding is set, update the output encoding
             pagerencoding = self.config("pager", "encoding")
@@ -847,6 +852,9 @@ class ui(object):
         # The Rust pager wants utf-8 unconditionally.
         encoding.outputencoding = "utf-8"
 
+        # Pass through whether output was a terminal
+        istty = self.terminaloutput()
+
         # Replace stream with write functions from the Rust pager.
         class stream(object):
             def __init__(self, writefunc):
@@ -861,6 +869,9 @@ class ui(object):
             def close(self):
                 pass
 
+            def isatty(self):
+                return istty
+
         assert isinstance(self.fout, util.refcell)
         assert isinstance(self.ferr, util.refcell)
         origfout = self.fout.swap(stream(pager.write))
@@ -1055,6 +1066,13 @@ class ui(object):
                 pass
         return scmutil.termsize(self)[0]
 
+    def terminaloutput(self):
+        """is output to a terminal?"""
+        istty = self._terminaloutput
+        if istty is None:
+            return self._isatty(self.fout)
+        return istty
+
     @util.propertycache
     def formatted(self):
         """should formatted output be used?

eden/scm/tests/test-diff-color.t

@@ -2,7 +2,7 @@
 
 Setup
 
-  $ setconfig ui.color=yes ui.formatted=always ui.paginate=never
+  $ setconfig ui.color=always ui.paginate=never
   $ setconfig color.mode=ansi
   $ hg init repo
   $ cd repo
@@ -49,7 +49,7 @@ default context
 
 (check that 'ui.color=yes' match '--color=auto')
 
-  $ hg diff --nodates --config ui.formatted=no
+  $ hg diff --nodates --config ui.color=yes
   diff -r cf9f4ba66af2 a
   --- a/a
   +++ b/a
@@ -65,7 +65,7 @@ default context
 
 (check that 'ui.color=no' disable color)
 
-  $ hg diff --nodates --config ui.formatted=yes --config ui.color=no
+  $ hg diff --nodates --config ui.color=no
   diff -r cf9f4ba66af2 a
   --- a/a
   +++ b/a
@@ -81,7 +81,7 @@ default context
 
 (check that 'ui.color=always' force color)
 
-  $ hg diff --nodates --config ui.formatted=no --config ui.color=always
+  $ hg diff --nodates --config ui.color=always
   \x1b[0;1mdiff -r cf9f4ba66af2 a\x1b[0m (esc)
   \x1b[0;31;1m--- a/a\x1b[0m (esc)
   \x1b[0;32;1m+++ b/a\x1b[0m (esc)

eden/scm/tests/test-pager.t

@@ -8,10 +8,9 @@
   >     sys.stdout.write('paged empty output!\n')
   > EOF
 
-Enable ui.formatted because pager won't fire without it, and set up
-pager and tell it to use our fake pager that lets us see when the
-pager was running.
-  $ setconfig ui.formatted=yes ui.color=no
+Enable ui.assume-tty so that the pager will start, and set the pager to our
+fake pager that lets us see when the pager was running.
+  $ setconfig ui.assume-tty=yes ui.color=no
   $ cat >>$HGRCPATH <<EOF
   > [pager]
   > pager = $PYTHON $TESTTMP/fakepager.py
@@ -147,7 +146,7 @@ Attend for an abbreviated command does not work
 
 Pager should not start if stdout is not a tty.
 
-  $ hg log -l1 -q --config ui.formatted=False
+  $ hg log -l1 -q --config ui.assume-tty=no
   10:46106edeeb38
 
 Pager should be disabled if pager.pager is empty (otherwise the output would

eden/scm/tests/test-ui-color.py

@@ -21,7 +21,7 @@ hgrc.write("color=\n")
 hgrc.close()
 
 ui_ = uimod.ui.load()
-ui_.setconfig("ui", "formatted", "True")
+ui_.setconfig("ui", "assume-tty", "True")
 
 # we're not interested in the output, so write that to devnull
 ui_.fout = open(os.devnull, "wb")