Add support for linking against a curses library when available and

using it to detect whether or not a terminal supports colors. This
replaces a particularly egregious hack that merely compared the TERM
environment variable to "dumb". That doesn't really translate to
a reasonable experience for users that have actually ensured their
terminal's capabilities are accurately reflected.

This makes testing a terminal for color support somewhat more expensive,
but it is called very rarely anyways. The important fast path when the
output is being piped somewhere is already in place.

The global lock may seem excessive, but the spec for calling into curses
is *terrible*. The whole library is terrible, and I spent quite a bit of
time looking for a better way of doing this before convincing myself
that this was the fundamentally correct way to behave. The damage of the
curses library is very narrowly confined, and we continue to use raw
escape codes for actually manipulating the colors which is a much sane
system than directly using curses here (IMO).

If this causes trouble for folks, please let me know. I've tested it on
Linux and will watch the bots carefully. I've also worked to account for
the variances of curses interfaces that I could finde documentation for,
but that may not have been sufficient.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187874 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 24 insertions, 0 deletions

diff --git a/autoconf/configure.ac b/autoconf/configure.ac
index 5be25af..30481ea 100644
--- a/autoconf/configure.ac
+++ b/autoconf/configure.ac
@@ -1072,6 +1072,17 @@ AC_ARG_WITH(bug-report-url,
 AC_DEFINE_UNQUOTED(BUG_REPORT_URL,"$withval",
                    [Bug report URL.])
 
+dnl --enable-curses: check whether the user wants to control use of curses:
+AC_ARG_ENABLE(curses,AS_HELP_STRING(
+  [--enable-curses],
+  [Use curses for querying terminal infomation if available (default is YES)]),
+  [case "$enableval" in
+    yes) llvm_cv_enable_curses="yes" ;;
+    no)  llvm_cv_enable_curses="no"  ;;
+    *) AC_MSG_ERROR([Invalid setting for --enable-curses. Use "yes" or "no"]) ;;
+  esac],
+  llvm_cv_enable_curses="yes")
+
 dnl --enable-libffi : check whether the user wants to turn off libffi:
 AC_ARG_ENABLE(libffi,AS_HELP_STRING(
   --enable-libffi,[Check for the presence of libffi (default is NO)]),
@@ -1378,6 +1389,14 @@ dnl macros to detect whether clock_gettime is available, this just finds the
 dnl right libraries to link with.
 AC_SEARCH_LIBS(clock_gettime,rt)
 
+dnl The curses library is optional; used for querying terminal info
+if test "$llvm_cv_enable_curses" = "yes" ; then
+  dnl We need the has_color functionality in curses for it to be useful.
+  AC_SEARCH_LIBS(has_colors,curses ncurses ncursesw,
+                 AC_DEFINE([HAVE_CURSES],[1],
+                           [Define if curses provides the has_color() function on this platform.]))
+fi
+
 dnl libffi is optional; used to call external functions from the interpreter
 if test "$llvm_cv_enable_libffi" = "yes" ; then
   AC_SEARCH_LIBS(ffi_call,ffi,AC_DEFINE([HAVE_FFI_CALL],[1],
@@ -1554,6 +1573,11 @@ else
   AC_SUBST(HAVE_LIBZ, 0)
 fi
 
+dnl Try to find a suitable curses header.
+if test "$llvm_cv_enable_curses" = "yes" ; then
+  AC_CHECK_HEADERS([curses.h ncurses.h ncursesw.h ncurses/curses.h ncursesw/curses.h])
+fi
+
 dnl Try to find ffi.h.
 if test "$llvm_cv_enable_libffi" = "yes" ; then
   AC_CHECK_HEADERS([ffi.h ffi/ffi.h])