Gregory Szorc 4732e7cb34 Bug 1171610 - Automatically enable color in compiler output; r=glandium
GCC and Clang will colorize compiler output automatically if stdout is a
TTY. Unfortunately, when the build backend is invoked via `mach`,
stdout is not a TTY.

6e9a4c0b9cd8 (bug 1315785) changed mach so it exports an environment
variable indicating whether mach's original stdout is a TTY. This was
later used to add color flags to `cargo` invocations.

Building on that work, this patch adds color flags to compiler
invocations if the compiler supports color and a mach TTY is
detected. The result is that compiler output from `mach build`
will be colorized automatically if Clang or a modern version of
GCC is used.

The only issue I see with this is that Clang doesn't "unset" its color
sequences when printing a newline. As a result, mach's time line
prefixing can sometimes inherit "bold" or other stylings. AFAICT this is
only a minor cosmetic concern. GCC does not exhibit this issue.

MozReview-Commit-ID: 5Icu6aXGZBL

--HG--
extra : rebase_source : 5b2bf5a287fdf8075b3d7dde36b91f3c65b60728
2016-11-09 14:01:24 -08:00
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