message: If env-var is set, don't build all targets
diff: @@ -342,8 +342,18 @@ impl RustwideBuilder {
  )?;
  successful_targets.push(res.target.clone());
  +
  + // this is a breaking change, don't enable it by default
  + let build_specific = std::env::var("DOCS_RS_BUILD_ONLY_SPECIFIED_TARGETS")
  + .map(|s| s == "true").unwrap_or(false);
  + let strs: Vec<_>;
  + let targets: &[&str] = if build_specific {
  + strs = metadata.extra_targets.iter().map(|s| s.as_str()).collect();
  + &strs
  + } else { TARGETS };
  +
  // Then build the documentation for all the targets
  - for target in TARGETS {
  + for target in targets {
  if *target == res.target {
  continue;
  }
  