Improve raw_ostream so that you can "write" colors using operator<<

1. raw_ostream supports ANSI colors so that you can write messages to
the termina with colors. Previously, in order to change and reset
color, you had to call `changeColor` and `resetColor` functions,
respectively.

So, if you print out "error: " in red, for example, you had to do
something like this:

  OS.changeColor(raw_ostream::RED);
  OS << "error: ";
  OS.resetColor();

With this patch, you can write the same code as follows:

  OS << raw_ostream::RED << "error: " << raw_ostream::RESET;

2. Add a boolean flag to raw_ostream so that you can disable colored
output. If you disable colors, changeColor, operator<<(Color),
resetColor and other color-related functions have no effect.

Most LLVM tools automatically prints out messages using colors, and
you can disable it by passing a flag such as `--disable-colors`.
This new flag makes it easy to write code that works that way.

Differential Revision: https://reviews.llvm.org/D65564

llvm-svn: 367649

1 files changed, 4 insertions, 7 deletions

diff --git a/llvm/tools/llvm-cov/llvm-cov.cpp b/llvm/tools/llvm-cov/llvm-cov.cpp
index 172ec9f..dabb8afe 100644
--- a/llvm/tools/llvm-cov/llvm-cov.cpp
+++ b/llvm/tools/llvm-cov/llvm-cov.cpp
@@ -83,13 +83,10 @@ int main(int argc, const char **argv) {
     }
   }
 
-  if (argc > 1) {
-    if (sys::Process::StandardErrHasColors())
-      errs().changeColor(raw_ostream::RED);
-    errs() << "Unrecognized command: " << argv[1] << ".\n\n";
-    if (sys::Process::StandardErrHasColors())
-      errs().resetColor();
-  }
+  if (argc > 1)
+    errs() << raw_ostream::RED << "Unrecognized command: " << argv[1] << ".\n\n"
+           << raw_ostream::RESET;
+
   helpMain(argc, argv);
   return 1;
 }