Replace direct print to stdout/stderr with pipes

This allows buffering warnings/errors messages from gcc

Author: facchinm

utils/utils.go

@@ -30,6 +30,7 @@
 package utils
 
 import (
+	"bufio"
 	"bytes"
 	"crypto/md5"
 	"encoding/hex"
@@ -291,33 +292,62 @@ func ExecCommand(ctx *types.Context, command *exec.Cmd, stdout int, stderr int)
 		ctx.GetLogger().UnformattedFprintln(os.Stdout, PrintableCommand(command.Args))
 	}
 
+	var stdoutCopy io.ReadCloser
+	var stderrCopy io.ReadCloser
+
 	if stdout == Capture {
 		buffer := &bytes.Buffer{}
 		command.Stdout = buffer
 	} else if stdout == Show || stdout == ShowIfVerbose && ctx.Verbose {
-		command.Stdout = os.Stdout
+		stdoutCopy, _ = command.StdoutPipe()
 	}
 
 	if stderr == Capture {
 		buffer := &bytes.Buffer{}
 		command.Stderr = buffer
 	} else if stderr == Show || stderr == ShowIfVerbose && ctx.Verbose {
-		command.Stderr = os.Stderr
+		stderrCopy, _ = command.StderrPipe()
 	}
 
 	err := command.Start()
 	if err != nil {
 		return nil, nil, i18n.WrapError(err)
 	}
 
-	err = command.Wait()
-
 	var outbytes, errbytes []byte
-	if buf, ok := command.Stdout.(*bytes.Buffer); ok {
-		outbytes = buf.Bytes()
+
+	if stdoutCopy != nil && stderrCopy != nil {
+		stdOut := bufio.NewScanner(stdoutCopy)
+		stdErr := bufio.NewScanner(stderrCopy)
+		stdOut.Split(bufio.ScanLines)
+		stdErr.Split(bufio.ScanLines)
+
+		go func() {
+			for stdOut.Scan() {
+				txt := stdOut.Text() + "\n"
+				fmt.Fprint(os.Stderr, txt)
+				outbytes = append(outbytes, txt...)
+			}
+		}()
+
+		go func() {
+			for stdErr.Scan() {
+				txt := stdErr.Text() + "\n"
+				fmt.Fprint(os.Stderr, txt)
+				errbytes = append(errbytes, txt...)
+			}
+		}()
 	}
-	if buf, ok := command.Stderr.(*bytes.Buffer); ok {
-		errbytes = buf.Bytes()
+
+	err = command.Wait()
+
+	if stdoutCopy == nil || stderrCopy == nil {
+		if buf, ok := command.Stdout.(*bytes.Buffer); ok {
+			outbytes = buf.Bytes()
+		}
+		if buf, ok := command.Stderr.(*bytes.Buffer); ok {
+			errbytes = buf.Bytes()
+		}
 	}
 
 	return outbytes, errbytes, i18n.WrapError(err)