Disable log grouping when --message-format option is used

Fixes #221

.github/workflows/ci.yml

@@ -70,6 +70,7 @@ jobs:
           cargo install --path . --debug
           cd tests/fixtures/real
           cargo hack check --feature-powerset --workspace
+          cargo hack check --feature-powerset --workspace --message-format=json
           cd ../rust-version
           rustup toolchain remove 1.63 1.64 1.65
           cargo hack check --rust-version --workspace

CHANGELOG.md

@@ -10,6 +10,8 @@ Note: In this file, do not use the hard wrap in the middle of a sentence for com
 
 ## [Unreleased]
 
+- Disable log grouping on GitHub Actions by default if an option is passed in which stdout is assumed to be used, such as `--message-format`. ([#221](https://github.com/taiki-e/cargo-hack/pull/221))
+
 ## [0.6.7] - 2023-09-11
 
 - Group rustup output on GitHub Actions. ([#219](https://github.com/taiki-e/cargo-hack/pull/219))

src/cli.rs

@@ -155,6 +155,7 @@ impl Args {
         let mut version_range = None;
         let mut version_step = None;
         let mut log_group: Option<String> = None;
+        let mut disable_log_grouping = false;
 
         let mut optional_deps = None;
         let mut include_features = vec![];
@@ -328,6 +329,10 @@ impl Args {
                 Long(flag) => {
                     removed_flags(flag)?;
                     similar_flags(flag, subcommand.as_deref())?;
+                    if matches!(flag, "message-format") {
+                        // https://github.com/taiki-e/cargo-hack/issues/221
+                        disable_log_grouping = true;
+                    }
                     let flag = format!("--{flag}");
                     if let Some(val) = parser.optional_value() {
                         cargo_args.push(format!("{flag}={}", val.string()?));
@@ -550,6 +555,7 @@ impl Args {
 
         let log_group = match log_group {
             Some(v) => v.parse()?,
+            None if disable_log_grouping => LogGroup::None,
             None => LogGroup::auto(),
         };