fix: binary archive when multiple builds

closes #3383

Signed-off-by: Carlos A Becker <caarlos0@users.noreply.github.com>

internal/pipe/archive/archive.go

@@ -32,7 +32,7 @@ const (
 // ErrArchiveDifferentBinaryCount happens when an archive uses several builds which have different goos/goarch/etc sets,
 // causing the archives for some platforms to have more binaries than others.
 // GoReleaser breaks in these cases as it will only cause confusion to other users.
-var ErrArchiveDifferentBinaryCount = errors.New("archive has different count of built binaries for each platform, which may cause your users confusion. Please make sure all builds used have the same set of goos/goarch/etc or split it into multiple archives")
+var ErrArchiveDifferentBinaryCount = errors.New("archive has different count of binaries for each platform, which may cause your users confusion.\nLearn more at https://goreleaser.com/errors/multiple-binaries-archive\n")
 
 // nolint: gochecknoglobals
 var lock sync.Mutex
@@ -96,7 +96,7 @@ func (Pipe) Run(ctx *context.Context) error {
 			filter = append(filter, artifact.ByIDs(archive.Builds...))
 		}
 		artifacts := ctx.Artifacts.Filter(artifact.And(filter...)).GroupByPlatform()
-		if err := checkArtifacts(artifacts); err != nil && !archive.AllowDifferentBinaryCount {
+		if err := checkArtifacts(artifacts); err != nil && archive.Format != "binary" && !archive.AllowDifferentBinaryCount {
 			return fmt.Errorf("invalid archive: %d: %w", i, ErrArchiveDifferentBinaryCount)
 		}
 		for group, artifacts := range artifacts {

www/docs/errors/multiple-binaries-archive.md

@@ -0,0 +1,51 @@
+# Archive has different count of binaries for each platform
+
+This error looks like this:
+
+```sh
+⨯ release failed after 5s                  error=invalid archive: 0:archive has different count of binaries for each platform, which may cause your users confusion.
+Learn more at https://goreleaser.com/errors/multiple-binaries-archive
+
+```
+
+This will happen when you have several builds, and their target platforms are
+different:
+
+```yaml
+builds:
+- id: b1
+  binary: b1
+  goos: [linux, darwin]
+- id: b2
+  binary: b2
+  goos: [darwin]
+
+archives:
+- id: a1
+```
+
+In this scenario, GoReleaser will complain because the archive will have a
+different binary count depending on which platform its being archived, since
+it'll have 2 binaries on `darwin` and only 1 on `linux`.
+
+
+From here on, you have a couple of options:
+
+- add another archive, and filter the builds on each of them - e.g. archive `a1`
+  with binaries from build `b1`, and archive `a2` with builds from build `b2`:
+  ```yaml
+  archives:
+  - id: a1
+    builds: b1
+    name_template: something-unique-for-a1
+  - id: a2
+    builds: b2
+    name_template: something-unique-for-a2
+  ```
+- if you really want to have the mixed archive, you can add
+  `allow_different_binary_count` to your archive configuration:
+  ```yaml
+  archives:
+  - id: a1
+    allow_different_binary_count: true
+  ```

www/mkdocs.yml

@@ -139,6 +139,7 @@ nav:
   - errors/no-main.md
   - errors/resource-not-accessible-by-integration.md
   - errors/no-history.md
+  - errors/multiple-binaries-archive.md
 - deprecations.md
 - Cookbooks:
   - About: cookbooks/index.md