fix: simplify flag & env

Signed-off-by: Etienne Marais <[email protected]>

bin/common.ml

@@ -668,13 +668,15 @@ module Builder = struct
             ~docs
             ~doc:"Explain why Dune decides to re-digest some files")
     and+ debug_package_logs =
+      let doc = "Always print the standard logs when building packages" in
       Arg.(
         value
         & flag
         & info
             [ "debug-package-logs" ]
             ~docs
-            ~doc:"Always print the standard logs when building packages")
+            ~doc
+            ~env:(Cmd.Env.info ~doc "DUNE_DEBUG_PACKAGE_LOGS"))
     and+ no_buffer =
       let doc =
         "Do not buffer the output of commands executed by dune. By default dune buffers \

doc/changes/10662.md

@@ -0,0 +1,3 @@
+- pkg: only logs the standard output when the command fails or the user explicitly requests it.
+  Add new flag `--debug-package-logs`, which force dune to display the stdout logs when dealing
+  with package management (#10662, @maiste)

test/blackbox-tests/test-cases/pkg/helpers.sh

@@ -5,11 +5,7 @@ dune="dune"
 pkg_root="_build/_private/default/.pkg"
 
 build_pkg() {
-  if [ $DUNE_DEBUG_PACKAGE_LOGS -eq 1 ] ; then
-    $dune build --debug-package-logs $pkg_root/$1/target/
-  else
     $dune build $pkg_root/$1/target/
-  fi
 }
 
 show_pkg() {