Detect stderr ttyhascolor at init (#265)

Author: jpsamaroo

src/GPUCompiler.jl

@@ -46,4 +46,8 @@ include("reflection.jl")
 include("precompile.jl")
 _precompile_()
 
+function __init__()
+    STDERR_HAS_COLOR[] = get(stderr, :color, false)
+end
+
 end # module

src/utils.jl

@@ -26,6 +26,8 @@ end
 
 using Logging
 
+const STDERR_HAS_COLOR = Ref{Bool}(false)
+
 # define safe loggers for use in generated functions (where task switches are not allowed)
 for level in [:debug, :info, :warn, :error]
     @eval begin
@@ -35,7 +37,7 @@ for level in [:debug, :info, :warn, :error]
             macrocall.args[1] = Symbol($"@$level")
             quote
                 old_logger = global_logger()
-                io = IOContext(Core.stderr, :color=>get(stderr, :color, false))
+                io = IOContext(Core.stderr, :color=>STDERR_HAS_COLOR[])
                 min_level = Logging.min_enabled_level(old_logger)
                 global_logger(Logging.ConsoleLogger(io, min_level))
                 ret = $(esc(macrocall))