feat: first class build targets (#3062)

Adds the ability to tell goreleaser to use the first-class Go ports as
targets.

Closes #3053

Signed-off-by: Carlos A Becker <caarlos0@gmail.com>

internal/builders/golang/build.go

@@ -68,29 +68,67 @@ func (*Builder) WithDefaults(build config.Build) (config.Build, error) {
 			build.Goamd64 = []string{"v1"}
 		}
 		targets, err := buildtarget.List(build)
-		build.Targets = targets
 		if err != nil {
 			return build, err
 		}
+		build.Targets = targets
 	} else {
-		for i, target := range build.Targets {
+		targets := map[string]bool{}
+		for _, target := range build.Targets {
+			if target == go118FirstClassTargetsName ||
+				target == goStableFirstClassTargetsName {
+				for _, t := range go118FirstClassTargets {
+					targets[t] = true
+				}
+				continue
+			}
 			if strings.HasSuffix(target, "_amd64") {
-				build.Targets[i] = target + "_v1"
+				targets[target+"_v1"] = true
+				continue
 			}
 			if strings.HasSuffix(target, "_arm") {
-				build.Targets[i] = target + "_6"
+				targets[target+"_6"] = true
+				continue
 			}
 			if strings.HasSuffix(target, "_mips") ||
 				strings.HasSuffix(target, "_mips64") ||
 				strings.HasSuffix(target, "_mipsle") ||
 				strings.HasSuffix(target, "_mips64le") {
-				build.Targets[i] = target + "_hardfloat"
+				targets[target+"_hardfloat"] = true
+				continue
 			}
+			targets[target] = true
 		}
+		build.Targets = keys(targets)
 	}
 	return build, nil
 }
 
+func keys(m map[string]bool) []string {
+	result := make([]string, 0, len(m))
+	for k := range m {
+		result = append(result, k)
+	}
+	return result
+}
+
+const (
+	go118FirstClassTargetsName    = "go_118_first_class"
+	goStableFirstClassTargetsName = "go_first_class"
+)
+
+// go tool dist list -json | jq -r '.[] | select(.FirstClass) | [.GOOS, .GOARCH] | @tsv'
+var go118FirstClassTargets = []string{
+	"darwin_amd64_v1",
+	"darwin_arm64",
+	"linux_386",
+	"linux_amd64_v1",
+	"linux_arm_6",
+	"linux_arm64",
+	"windows_386",
+	"windows_amd64_v1",
+}
+
 // Build builds a golang build.
 func (*Builder) Build(ctx *context.Context, build config.Build, options api.Options) error {
 	if err := checkMain(build); err != nil {

internal/builders/golang/build_test.go

@@ -185,6 +185,42 @@ func TestWithDefaults(t *testing.T) {
 			},
 			goBinary: "go",
 		},
+		"go first class targets": {
+			build: config.Build{
+				ID:      "foo3",
+				Binary:  "foo",
+				Targets: []string{goStableFirstClassTargetsName},
+			},
+			targets:  go118FirstClassTargets,
+			goBinary: "go",
+		},
+		"go 1.18 first class targets": {
+			build: config.Build{
+				ID:      "foo3",
+				Binary:  "foo",
+				Targets: []string{go118FirstClassTargetsName},
+			},
+			targets:  go118FirstClassTargets,
+			goBinary: "go",
+		},
+		"go 1.18 first class targets plus custom": {
+			build: config.Build{
+				ID:      "foo3",
+				Binary:  "foo",
+				Targets: []string{"linux_amd64_v1", go118FirstClassTargetsName, "darwin_amd64_v2"},
+			},
+			targets:  append(go118FirstClassTargets, "darwin_amd64_v2"),
+			goBinary: "go",
+		},
+		"repeatin targets": {
+			build: config.Build{
+				ID:      "foo3",
+				Binary:  "foo",
+				Targets: []string{go118FirstClassTargetsName, go118FirstClassTargetsName, goStableFirstClassTargetsName},
+			},
+			targets:  go118FirstClassTargets,
+			goBinary: "go",
+		},
 	} {
 		t.Run(name, func(t *testing.T) {
 			if testcase.build.GoBinary != "" && testcase.build.GoBinary != "go" {

www/docs/customization/build.md

@@ -2,8 +2,8 @@
 
 Builds can be customized in multiple ways.
 You can specify for which `GOOS`, `GOARCH` and `GOARM` binaries are built
-(goreleaser will generate a matrix of all combinations), and you can change
-the name of the binary, flags, environment variables, hooks and etc.
+(GoReleaser will generate a matrix of all combinations), and you can change
+the name of the binary, flags, environment variables, hooks and more.
 
 Here is a commented `builds` section with all fields specified:
 
@@ -119,9 +119,16 @@ builds:
 
     # Optionally override the matrix generation and specify only the final list of targets.
     # Format is `{goos}_{goarch}` with optionally a suffix with `_{goarm}`, `_{goamd64}` or `_{gomips}`.
+    #
+    # Special values:
+    # - go_118_first_class: evaluates to the first-class targets of go1.18
+    # - go_first_class: evaluates to latest stable go first-class targets, currently same as 1.18.
+    #
     # This overrides `goos`, `goarch`, `goarm`, `gomips`, `goamd64` and `ignores`.
     targets:
-      - linux_amd64
+      - go_first_class
+      - go_118_first_class
+      - linux_amd64_v1
       - darwin_arm64
       - linux_arm_6
 
@@ -202,6 +209,13 @@ builds:
 !!! tip
     Learn more about the [name template engine](/customization/templates/).
 
+!!! info
+    First-class build targets are gathered by running:
+    ```sh
+    go tool dist list -json | jq -r '.[] | select(.FirstClass) | [.GOOS, .GOARCH] | @tsv'
+    ```
+    We also recommend reading the [official wiki about Go ports](https://github.com/golang/go/wiki/PortingPolicy#first-class-ports).
+
 Here is an example with multiple binaries:
 
 ```yaml
@@ -350,7 +364,7 @@ This is useful in scenarios where two tags point to the same commit.
 
 ## Reproducible Builds
 
-To make your releases, checksums, and signatures reproducible, you will need to make some (if not all) of the following modifications to the build defaults in GoReleaser:
+To make your releases, checksums and signatures reproducible, you will need to make some (if not all) of the following modifications to the build defaults in GoReleaser:
 
 * Modify `ldflags`: by default `main.Date` is set to the time GoReleaser is run (`{{.Date}}`), you can set this to `{{.CommitDate}}` or just not pass the variable.
 * Modify `mod_timestamp`: by default this is empty string, set to `{{.CommitTimestamp}}` or a constant value instead.
@@ -422,5 +436,6 @@ There is no difference in how the binaries are handled.
     GoReleaser will fail.
 
 !!! warning
-    When using the `prebuilt` binary, there are no defaults for `goos` et al,
-    so you need to either provide those or the final `targets` matrix.
+    When using the `prebuilt` binary, there are no defaults for `goos`,
+    `goarch`, `goarm`, `gomips` and `goamd64`.
+    You'll need to either provide them or the final `targets` matrix.