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

9 files changed, 432 insertions, 11 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 687176c..a0a6c75 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -123,6 +123,8 @@ set(FFI_INCLUDE_DIR "" CACHE PATH "Additional directory, where CMake should sear
 set(LLVM_TARGET_ARCH "host"
   CACHE STRING "Set target to use for LLVM JIT or use \"host\" for automatic detection.")
 
+option(LLVM_ENABLE_CURSES "Use curses to detect terminal info if available." ON)
+
 option(LLVM_ENABLE_THREADS "Use threads if available." ON)
 
 option(LLVM_ENABLE_ZLIB "Use zlib for compression/decompression if available." ON)
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])
diff --git a/cmake/config-ix.cmake b/cmake/config-ix.cmake
index 85c4d81..0567820 100755
--- a/cmake/config-ix.cmake
+++ b/cmake/config-ix.cmake
@@ -74,6 +74,12 @@ check_symbol_exists(FE_INEXACT "fenv.h" HAVE_DECL_FE_INEXACT)
 check_include_file(mach/mach.h HAVE_MACH_MACH_H)
 check_include_file(mach-o/dyld.h HAVE_MACH_O_DYLD_H)
 
+check_include_file(curses.h HAVE_CURSES_H)
+check_include_file(ncurses.h HAVE_NCURSES_H)
+check_include_file(ncursesw.h HAVE_NCURSESW_H)
+check_include_file(ncurses/curses.h HAVE_NCURSES_CURSES_H)
+check_include_file(ncursesw/curses.h HAVE_NCURSESW_CURSES_H)
+
 # library checks
 if( NOT PURE_WINDOWS )
   check_library_exists(pthread pthread_create "" HAVE_LIBPTHREAD)
@@ -97,6 +103,19 @@ if( NOT PURE_WINDOWS )
   else()
     set(HAVE_LIBZ 0)
   endif()
+  if(LLVM_ENABLE_CURSES)
+    check_library_exists(curses has_colors "" HAVE_CURSES)
+    if(NOT HAVE_CURSES)
+      check_library_exists(ncurses has_colors "" HAVE_NCURSES)
+      set(HAVE_CURSES ${HAVE_NCURSES})
+      if(NOT HAVE_CURSES)
+        check_library_exists(ncursesw has_colors "" HAVE_NCURSESW)
+        set(HAVE_CURSES ${HAVE_NCURSESW})
+      endif()
+    endif()
+  else()
+    set(HAVE_CURSES 0)
+  endif()
 endif()
 
 # function checks
diff --git a/cmake/modules/LLVM-Config.cmake b/cmake/modules/LLVM-Config.cmake
index 2ddc0b2..3e2447a 100644
--- a/cmake/modules/LLVM-Config.cmake
+++ b/cmake/modules/LLVM-Config.cmake
@@ -10,6 +10,15 @@ function(get_system_libs return_var)
       if( HAVE_LIBDL )
         set(system_libs ${system_libs} ${CMAKE_DL_LIBS})
       endif()
+      if(LLVM_ENABLE_CURSES)
+        if(HAVE_NCURSESW)
+          set(system_libs ${system_libs} ncursesw)
+        elseif(HAVE_NCURSES)
+          set(system_libs ${system_libs} ncurses)
+        elseif(HAVE_CURSES)
+          set(system_libs ${system_libs} curses)
+        endif()
+      endif()
       if( LLVM_ENABLE_THREADS AND HAVE_LIBPTHREAD )
         set(system_libs ${system_libs} pthread)
       endif()
diff --git a/cmake/modules/LLVMConfig.cmake.in b/cmake/modules/LLVMConfig.cmake.in
index f0b8c14..ae2bc59 100644
--- a/cmake/modules/LLVMConfig.cmake.in
+++ b/cmake/modules/LLVMConfig.cmake.in
@@ -20,6 +20,8 @@ set(TARGET_TRIPLE "@TARGET_TRIPLE@")
 
 set(LLVM_TOOLS_BINARY_DIR @LLVM_TOOLS_BINARY_DIR@)
 
+set(LLVM_ENABLE_CURSES @LLVM_ENABLE_CURSES@)
+
 set(LLVM_ENABLE_THREADS @LLVM_ENABLE_THREADS@)
 
 set(LLVM_ENABLE_ZLIB @LLVM_ENABLE_ZLIB@)
diff --git a/configure b/configure
index 242f764..a148711 100755
--- a/configure
+++ b/configure
@@ -1453,6 +1453,8 @@ Optional Features:
                           target1,target2,... (default=disable)
   --enable-bindings       Build specific language bindings:
                           all,auto,none,{binding-name} (default=auto)
+  --enable-curses         Use curses for querying terminal infomation if
+                          available (default is YES)
   --enable-libffi         Check for the presence of libffi (default is NO)
   --enable-ltdl-install   install libltdl
 
@@ -6004,6 +6006,20 @@ cat >>confdefs.h <<_ACEOF
 _ACEOF
 
 
+# Check whether --enable-curses was given.
+if test "${enable_curses+set}" = set; then
+  enableval=$enable_curses; case "$enableval" in
+    yes) llvm_cv_enable_curses="yes" ;;
+    no)  llvm_cv_enable_curses="no"  ;;
+    *) { { echo "$as_me:$LINENO: error: Invalid setting for --enable-curses. Use \"yes\" or \"no\"" >&5
+echo "$as_me: error: Invalid setting for --enable-curses. Use \"yes\" or \"no\"" >&2;}
+   { (exit 1); exit 1; }; } ;;
+  esac
+else
+  llvm_cv_enable_curses="yes"
+fi
+
+
 # Check whether --enable-libffi was given.
 if test "${enable_libffi+set}" = set; then
   enableval=$enable_libffi; case "$enableval" in
@@ -10545,7 +10561,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<EOF
-#line 10548 "configure"
+#line 10564 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -12252,6 +12268,112 @@ if test "$ac_res" != no; then
 fi
 
 
+if test "$llvm_cv_enable_curses" = "yes" ; then
+    { echo "$as_me:$LINENO: checking for library containing has_colors" >&5
+echo $ECHO_N "checking for library containing has_colors... $ECHO_C" >&6; }
+if test "${ac_cv_search_has_colors+set}" = set; then
+  echo $ECHO_N "(cached) $ECHO_C" >&6
+else
+  ac_func_search_save_LIBS=$LIBS
+cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+
+/* Override any GCC internal prototype to avoid an error.
+   Use char because int might match the return type of a GCC
+   builtin and then its argument prototype would still apply.  */
+#ifdef __cplusplus
+extern "C"
+#endif
+char has_colors ();
+int
+main ()
+{
+return has_colors ();
+  ;
+  return 0;
+}
+_ACEOF
+for ac_lib in '' curses ncurses ncursesw; do
+  if test -z "$ac_lib"; then
+    ac_res="none required"
+  else
+    ac_res=-l$ac_lib
+    LIBS="-l$ac_lib  $ac_func_search_save_LIBS"
+  fi
+  rm -f conftest.$ac_objext conftest$ac_exeext
+if { (ac_try="$ac_link"
+case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
+  (eval "$ac_link") 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } &&
+	 { ac_try='test -z "$ac_c_werror_flag" || test ! -s conftest.err'
+  { (case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
+  (eval "$ac_try") 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; } &&
+	 { ac_try='test -s conftest$ac_exeext'
+  { (case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
+  (eval "$ac_try") 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; }; then
+  ac_cv_search_has_colors=$ac_res
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+
+fi
+
+rm -f core conftest.err conftest.$ac_objext \
+      conftest$ac_exeext
+  if test "${ac_cv_search_has_colors+set}" = set; then
+  break
+fi
+done
+if test "${ac_cv_search_has_colors+set}" = set; then
+  :
+else
+  ac_cv_search_has_colors=no
+fi
+rm conftest.$ac_ext
+LIBS=$ac_func_search_save_LIBS
+fi
+{ echo "$as_me:$LINENO: result: $ac_cv_search_has_colors" >&5
+echo "${ECHO_T}$ac_cv_search_has_colors" >&6; }
+ac_res=$ac_cv_search_has_colors
+if test "$ac_res" != no; then
+  test "$ac_res" = "none required" || LIBS="$ac_res $LIBS"
+
+cat >>confdefs.h <<\_ACEOF
+#define HAVE_CURSES 1
+_ACEOF
+
+fi
+
+fi
+
 if test "$llvm_cv_enable_libffi" = "yes" ; then
   { echo "$as_me:$LINENO: checking for library containing ffi_call" >&5
 echo $ECHO_N "checking for library containing ffi_call... $ECHO_C" >&6; }
@@ -16421,6 +16543,182 @@ else
 
 fi
 
+if test "$llvm_cv_enable_curses" = "yes" ; then
+
+
+
+
+
+for ac_header in curses.h ncurses.h ncursesw.h ncurses/curses.h ncursesw/curses.h
+do
+as_ac_Header=`echo "ac_cv_header_$ac_header" | $as_tr_sh`
+if { as_var=$as_ac_Header; eval "test \"\${$as_var+set}\" = set"; }; then
+  { echo "$as_me:$LINENO: checking for $ac_header" >&5
+echo $ECHO_N "checking for $ac_header... $ECHO_C" >&6; }
+if { as_var=$as_ac_Header; eval "test \"\${$as_var+set}\" = set"; }; then
+  echo $ECHO_N "(cached) $ECHO_C" >&6
+fi
+ac_res=`eval echo '${'$as_ac_Header'}'`
+	       { echo "$as_me:$LINENO: result: $ac_res" >&5
+echo "${ECHO_T}$ac_res" >&6; }
+else
+  # Is the header compilable?
+{ echo "$as_me:$LINENO: checking $ac_header usability" >&5
+echo $ECHO_N "checking $ac_header usability... $ECHO_C" >&6; }
+cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+$ac_includes_default
+#include <$ac_header>
+_ACEOF
+rm -f conftest.$ac_objext
+if { (ac_try="$ac_compile"
+case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
+  (eval "$ac_compile") 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } &&
+	 { ac_try='test -z "$ac_c_werror_flag" || test ! -s conftest.err'
+  { (case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
+  (eval "$ac_try") 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; } &&
+	 { ac_try='test -s conftest.$ac_objext'
+  { (case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
+  (eval "$ac_try") 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; }; then
+  ac_header_compiler=yes
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+	ac_header_compiler=no
+fi
+
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+{ echo "$as_me:$LINENO: result: $ac_header_compiler" >&5
+echo "${ECHO_T}$ac_header_compiler" >&6; }
+
+# Is the header present?
+{ echo "$as_me:$LINENO: checking $ac_header presence" >&5
+echo $ECHO_N "checking $ac_header presence... $ECHO_C" >&6; }
+cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+#include <$ac_header>
+_ACEOF
+if { (ac_try="$ac_cpp conftest.$ac_ext"
+case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
+  (eval "$ac_cpp conftest.$ac_ext") 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } >/dev/null; then
+  if test -s conftest.err; then
+    ac_cpp_err=$ac_c_preproc_warn_flag
+    ac_cpp_err=$ac_cpp_err$ac_c_werror_flag
+  else
+    ac_cpp_err=
+  fi
+else
+  ac_cpp_err=yes
+fi
+if test -z "$ac_cpp_err"; then
+  ac_header_preproc=yes
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+  ac_header_preproc=no
+fi
+
+rm -f conftest.err conftest.$ac_ext
+{ echo "$as_me:$LINENO: result: $ac_header_preproc" >&5
+echo "${ECHO_T}$ac_header_preproc" >&6; }
+
+# So?  What about this header?
+case $ac_header_compiler:$ac_header_preproc:$ac_c_preproc_warn_flag in
+  yes:no: )
+    { echo "$as_me:$LINENO: WARNING: $ac_header: accepted by the compiler, rejected by the preprocessor!" >&5
+echo "$as_me: WARNING: $ac_header: accepted by the compiler, rejected by the preprocessor!" >&2;}
+    { echo "$as_me:$LINENO: WARNING: $ac_header: proceeding with the compiler's result" >&5
+echo "$as_me: WARNING: $ac_header: proceeding with the compiler's result" >&2;}
+    ac_header_preproc=yes
+    ;;
+  no:yes:* )
+    { echo "$as_me:$LINENO: WARNING: $ac_header: present but cannot be compiled" >&5
+echo "$as_me: WARNING: $ac_header: present but cannot be compiled" >&2;}
+    { echo "$as_me:$LINENO: WARNING: $ac_header:     check for missing prerequisite headers?" >&5
+echo "$as_me: WARNING: $ac_header:     check for missing prerequisite headers?" >&2;}
+    { echo "$as_me:$LINENO: WARNING: $ac_header: see the Autoconf documentation" >&5
+echo "$as_me: WARNING: $ac_header: see the Autoconf documentation" >&2;}
+    { echo "$as_me:$LINENO: WARNING: $ac_header:     section \"Present But Cannot Be Compiled\"" >&5
+echo "$as_me: WARNING: $ac_header:     section \"Present But Cannot Be Compiled\"" >&2;}
+    { echo "$as_me:$LINENO: WARNING: $ac_header: proceeding with the preprocessor's result" >&5
+echo "$as_me: WARNING: $ac_header: proceeding with the preprocessor's result" >&2;}
+    { echo "$as_me:$LINENO: WARNING: $ac_header: in the future, the compiler will take precedence" >&5
+echo "$as_me: WARNING: $ac_header: in the future, the compiler will take precedence" >&2;}
+    ( cat <<\_ASBOX
+## ------------------------------------ ##
+## Report this to http://llvm.org/bugs/ ##
+## ------------------------------------ ##
+_ASBOX
+     ) | sed "s/^/$as_me: WARNING:     /" >&2
+    ;;
+esac
+{ echo "$as_me:$LINENO: checking for $ac_header" >&5
+echo $ECHO_N "checking for $ac_header... $ECHO_C" >&6; }
+if { as_var=$as_ac_Header; eval "test \"\${$as_var+set}\" = set"; }; then
+  echo $ECHO_N "(cached) $ECHO_C" >&6
+else
+  eval "$as_ac_Header=\$ac_header_preproc"
+fi
+ac_res=`eval echo '${'$as_ac_Header'}'`
+	       { echo "$as_me:$LINENO: result: $ac_res" >&5
+echo "${ECHO_T}$ac_res" >&6; }
+
+fi
+if test `eval echo '${'$as_ac_Header'}'` = yes; then
+  cat >>confdefs.h <<_ACEOF
+#define `echo "HAVE_$ac_header" | $as_tr_cpp` 1
+_ACEOF
+
+fi
+
+done
+
+fi
+
 if test "$llvm_cv_enable_libffi" = "yes" ; then
 
 
diff --git a/include/llvm/Config/config.h.cmake b/include/llvm/Config/config.h.cmake
index b34c404..4b0aa4b 100644
--- a/include/llvm/Config/config.h.cmake
+++ b/include/llvm/Config/config.h.cmake
@@ -48,6 +48,12 @@
 /* Define to 1 if you have the `closedir' function. */
 #cmakedefine HAVE_CLOSEDIR ${HAVE_CLOSEDIR}
 
+/* Define if curses provides the has_color() function on this platform. */
+#cmakedefine HAVE_CURSES
+
+/* Define to 1 if you have the <curses.h> header file. */
+#cmakedefine HAVE_CURSES_H
+
 /* Define to 1 if you have the <cxxabi.h> header file. */
 #cmakedefine HAVE_CXXABI_H ${HAVE_CXXABI_H}
 
@@ -256,6 +262,18 @@
 /* Define if mmap() can map files into memory */
 #undef HAVE_MMAP_FILE
 
+/* Define to 1 if you have the <ncursesw/curses.h> header file. */
+#cmakedefine HAVE_NCURSESW_CURSES_H
+
+/* Define to 1 if you have the <ncursesw.h> header file. */
+#cmakedefine HAVE_NCURSESW_H
+
+/* Define to 1 if you have the <ncurses/curses.h> header file. */
+#cmakedefine HAVE_NCURSES_CURSES_H
+
+/* Define to 1 if you have the <ncurses.h> header file. */
+#cmakedefine HAVE_NCURSES_H
+
 /* Define to 1 if you have the <ndir.h> header file, and it defines `DIR'. */
 #cmakedefine HAVE_NDIR_H ${HAVE_NDIR_H}
 
diff --git a/include/llvm/Config/config.h.in b/include/llvm/Config/config.h.in
index 74b7829..7bb1caa 100644
--- a/include/llvm/Config/config.h.in
+++ b/include/llvm/Config/config.h.in
@@ -69,6 +69,12 @@
 /* can use __crashreporter_info__ */
 #undef HAVE_CRASHREPORTER_INFO
 
+/* Define if curses provides the has_color() function on this platform. */
+#undef HAVE_CURSES
+
+/* Define to 1 if you have the <curses.h> header file. */
+#undef HAVE_CURSES_H
+
 /* Define to 1 if you have the <cxxabi.h> header file. */
 #undef HAVE_CXXABI_H
 
@@ -282,6 +288,18 @@
 /* Define if mmap() can map files into memory */
 #undef HAVE_MMAP_FILE
 
+/* Define to 1 if you have the <ncursesw/curses.h> header file. */
+#undef HAVE_NCURSESW_CURSES_H
+
+/* Define to 1 if you have the <ncursesw.h> header file. */
+#undef HAVE_NCURSESW_H
+
+/* Define to 1 if you have the <ncurses/curses.h> header file. */
+#undef HAVE_NCURSES_CURSES_H
+
+/* Define to 1 if you have the <ncurses.h> header file. */
+#undef HAVE_NCURSES_H
+
 /* Define to 1 if you have the <ndir.h> header file, and it defines `DIR'. */
 #undef HAVE_NDIR_H
 
diff --git a/lib/Support/Unix/Process.inc b/lib/Support/Unix/Process.inc
index 1335b78..0a797f6 100644
--- a/lib/Support/Unix/Process.inc
+++ b/lib/Support/Unix/Process.inc
@@ -13,6 +13,8 @@
 
 #include "Unix.h"
 #include "llvm/ADT/Hashing.h"
+#include "llvm/Support/Mutex.h"
+#include "llvm/Support/MutexGuard.h"
 #include "llvm/Support/TimeValue.h"
 #ifdef HAVE_SYS_TIME_H
 #include <sys/time.h>
@@ -36,6 +38,25 @@
 #  include <termios.h>
 #endif
 
+// See if we can use curses to detect information about a terminal when
+// connected to one.
+#ifdef HAVE_CURSES
+# if defined(HAVE_CURSES_H)
+#  include <curses.h>
+# elif defined(HAVE_NCURSES_H)
+#  include <ncurses.h>
+# elif defined(HAVE_NCURSESW_H)
+#  include <ncursesw.h>
+# elif defined(HAVE_NCURSES_CURSES_H)
+#  include <ncurses/curses.h>
+# elif defined(HAVE_NCURSESW_CURSES_H)
+#  include <ncursesw/curses.h>
+# else
+#  error Have a curses library but unable to find a curses header!
+# endif
+# include <term.h>
+#endif
+
 //===----------------------------------------------------------------------===//
 //=== WARNING: Implementation here must contain only generic UNIX code that
 //===          is guaranteed to work on *all* UNIX variants.
@@ -245,22 +266,32 @@ unsigned Process::StandardErrColumns() {
   return getColumns(2);
 }
 
-static bool terminalHasColors() {
-  if (const char *term = std::getenv("TERM")) {
-    // Most modern terminals support ANSI escape sequences for colors.
-    // We could check terminfo, or have a list of known terms that support
-    // colors, but that would be overkill.
-    // The user can always ask for no colors by setting TERM to dumb, or
-    // using a commandline flag.
-    return strcmp(term, "dumb") != 0;
-  }
+static bool terminalHasColors(int fd) {
+#ifdef HAVE_CURSES
+  // First, acquire a global lock because the curses C routines are thread
+  // hostile.
+  static sys::Mutex M;
+  MutexGuard G(M);
+
+  int errret = 0;
+  if (setupterm((char *)0, fd, &errret) != OK)
+    // Regardless of why, if we can't get terminfo, we shouldn't try to print
+    // colors.
+    return false;
+
+  // Test whether the terminal as set up supports color output.
+  if (has_colors() == TRUE)
+    return true;
+#endif
+
+  // Otherwise, be conservative.
   return false;
 }
 
 bool Process::FileDescriptorHasColors(int fd) {
   // A file descriptor has colors if it is displayed and the terminal has
   // colors.
-  return FileDescriptorIsDisplayed(fd) && terminalHasColors();
+  return FileDescriptorIsDisplayed(fd) && terminalHasColors(fd);
 }
 
 bool Process::StandardOutHasColors() {