From f16e24f95e7d7fa3a5c3b2c8d43d171fa5b9cf85 Mon Sep 17 00:00:00 2001
From: Daiderd Jordan <daiderd@gmail.com>
Date: Sat, 2 May 2020 10:58:33 +0200
Subject: [PATCH 1/2] remote-store: don't log raw stderr by default

For remote stores the log messages are already forwarded as structured
STDERR_RESULT messages so the old format is duplicate information.  But
still included with -vvv since it could be useful for debugging
problems.

    $ nix build -L /nix/store/nl71b2niws857ffiaggyrkjwgx9jjzc0-foo.drv --store ssh-ng://localhost
    Hello World!
    foo> Hello World!
    [1/0/1 built] building foo

Fixes #3556
---
 src/libstore/remote-store.cc | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/libstore/remote-store.cc b/src/libstore/remote-store.cc
index 8c55da268..07ef79382 100644
--- a/src/libstore/remote-store.cc
+++ b/src/libstore/remote-store.cc
@@ -779,8 +779,10 @@ std::exception_ptr RemoteStore::Connection::processStderr(Sink * sink, Source *
             return std::make_exception_ptr(Error(status, error));
         }
 
-        else if (msg == STDERR_NEXT)
-            printError(chomp(readString(from)));
+        else if (msg == STDERR_NEXT) {
+            string s = chomp(readString(from));
+            printMsg(lvlVomit, "stderr %s", s);
+        }
 
         else if (msg == STDERR_START_ACTIVITY) {
             auto act = readNum<ActivityId>(from);

From 4769eea5e2229c01c3b5d050891b071a45a024d5 Mon Sep 17 00:00:00 2001
From: Daiderd Jordan <daiderd@gmail.com>
Date: Sat, 2 May 2020 23:26:12 +0200
Subject: [PATCH 2/2] logging: handle build log lines in simple logger

The raw stderr output isn't logged anymore so the build logs need to be
printed by the default logger in order for the old commands like
nix-build to still show build output.
---
 src/libutil/logging.cc | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/src/libutil/logging.cc b/src/libutil/logging.cc
index 3cc4ef8f1..777650de5 100644
--- a/src/libutil/logging.cc
+++ b/src/libutil/logging.cc
@@ -63,6 +63,16 @@ public:
         writeToStderr(prefix + filterANSIEscapes(fs.s, !tty) + "\n");
     }
 
+    void result(ActivityId act, ResultType type, const std::vector<Field> & fields) override
+    {
+        if (type == resBuildLogLine || type == resPostBuildLogLine) {
+            assert(0 < fields.size());
+            assert(fields[0].type == Logger::Field::tString);
+            auto lastLine = fields[0].s;
+            log(lvlInfo, lastLine);
+        }
+    }
+
     void startActivity(ActivityId act, Verbosity lvl, ActivityType type,
         const std::string & s, const Fields & fields, ActivityId parent)
         override