Add support for GOEXPERIMENT

.plzconfig

@@ -175,5 +175,9 @@ Repeatable = true
 Optional = true
 Help = Build tags to pass to the Go compiler
 
+[PluginConfig "experiment"]
+Optional = true
+Help = Value to pass for GOEXPERIMENT
+
 [Plugin "shell"]
 Target = //plugins:shell

build_defs/go.build_defs

@@ -97,7 +97,10 @@ def _go_toolchain(name:str, srcs:list, labels:list=[], copy_cmd:str, visibility:
             'link': f'{name}/pkg/tool/{CONFIG.HOSTOS}_{CONFIG.HOSTARCH}/link',
             'cover': f'{name}/pkg/tool/{CONFIG.HOSTOS}_{CONFIG.HOSTARCH}/cover',
         },
-        tools = {"CC": [CONFIG.GO.CC_TOOL]} if CONFIG.GO.CGO_ENABLED else {},
+        env = _goexperiment_env(),
+        tools = ({
+          "CC": [CONFIG.GO.CC_TOOL],
+        } if CONFIG.GO.CGO_ENABLED == "1" else {}) | _goexperiment_env(),
         binary = True,
         labels = labels,
         visibility = visibility,
@@ -210,6 +213,7 @@ def go_stdlib(name:str, tags:list=CONFIG.GO.BUILD_TAGS, labels:list=[], visibili
             "GOOS": CONFIG.OS,
             "GOARCH": CONFIG.ARCH,
             "GODEBUG": "installgoroot=all",
+            "GOEXPERIMENT": CONFIG.GO.EXPERIMENT,
         },
         labels = ["go_pkg_info", "go_stdlib", "go"] + labels,
         output_is_complete = True,
@@ -293,6 +297,7 @@ def go_library(name:str, srcs:list, resources:list=[], asm_srcs:list=None, hdrs:
             test_only = test_only,
             deps = deps,
         )
+        link_prefix, _, _ = _module.partition('@')
     else:
         # Dummy modinfo so we don't have to provide everything for binary modinfo actions.
         modinfo = filegroup(
@@ -302,6 +307,7 @@ def go_library(name:str, srcs:list, resources:list=[], asm_srcs:list=None, hdrs:
             requires = ["modinfo"],
             test_only = test_only,
         )
+        link_prefix = ''
     deps += [modinfo]
 
     # We could just depend on go_src for all our deps but that would mean bringing in srcs for targets outside this
@@ -493,6 +499,7 @@ def go_library(name:str, srcs:list, resources:list=[], asm_srcs:list=None, hdrs:
         outs = outs,
         cmd = cmds,
         visibility = visibility,
+        env = _goexperiment_env(),
         building_description = "Compiling...",
         requires = ['go'],
         provides = provides,
@@ -503,6 +510,12 @@ def go_library(name:str, srcs:list, resources:list=[], asm_srcs:list=None, hdrs:
         exported_deps = exported_deps,
     )
 
+
+def _goexperiment_env():
+    """Returns the GOEXPERIMENT env var, or None if there isn't one."""
+    return {"GOEXPERIMENT": CONFIG.GO.EXPERIMENT} if CONFIG.GO.EXPERIMENT else {}
+
+
 def _generate_pkg_import_cfg_cmd(name, out, pkg_location, handle_basename_eq_dirname=False):
     """
     Generates a .importconfig file for all .a files within a go pkg directory for use with
@@ -648,6 +661,7 @@ def go_binary(name:str, srcs:list=[], resources:list=None, asm_srcs:list=[], out
         building_description="Linking...",
         needs_transitive_deps=True,
         binary=True,
+        env = _goexperiment_env(),
         output_is_complete=True,
         test_only=test_only,
         tools=tools,
@@ -829,6 +843,7 @@ def go_test(name:str, srcs:list, resources:list=None, data:list|dict=None, deps:
         env["GOCOVERDIR"] = "$TMP_DIR"
     else:
         env = {"GOCOVERDIR": "$TMP_DIR"}
+    env |= _goexperiment_env()
 
     return build_rule(
         name = name,
@@ -966,6 +981,7 @@ def go_benchmark(name:str, srcs:list, resources:list=None, data:list|dict=None,
         visibility=visibility,
         sandbox=sandbox,
         build_timeout=timeout,
+        env = _goexperiment_env(),
         requires=['go', 'test'],
         labels=labels,
         binary=True,
@@ -1475,7 +1491,7 @@ def go_module(name:str='', module:str, version:str='', download:str='', deps:lis
         visibility = visibility,
         licences = licences,
         linker_flags = linker_flags,
-        env = env,
+        env = env | {"GOEXPERIMENT": CONFIG.GO.EXPERIMENT},
         build_tags = build_tags,
         labels = labels if binary else [],
     )

test/BUILD

@@ -14,4 +14,4 @@ genrule(
     deps = exports,
     visibility=["//test/..."],
     tools = [CONFIG.E2E.PLEASE_TOOL],
-)
+)

test/goexperiment/BUILD

@@ -0,0 +1,7 @@
+subinclude("//test/build_defs:e2e")
+
+please_repo_e2e_test(
+    name = "goexperiment_test",
+    plz_command = "plz test",
+    repo = "test_repo",
+)

test/goexperiment/test_repo/.plzconfig

@@ -0,0 +1,10 @@
+[Parse]
+BuildFileName = BUILD_FILE
+BuildFileName = BUILD
+PreloadSubincludes = ///go//build_defs:go
+
+[Plugin "go"]
+ImportPath = github.com/please-build/please-rules/root-test
+Target = //plugins:go
+Stdlib = //third_party/go:std
+experiment = rangefunc

test/goexperiment/test_repo/experiment/BUILD_FILE

@@ -0,0 +1,4 @@
+go_test(
+    name = "experiment_test",
+    srcs = ["experiment_test.go"],
+)

test/goexperiment/test_repo/experiment/experiment_test.go

@@ -0,0 +1,28 @@
+package experiment_test
+
+import (
+	"iter"
+	"slices"
+	"testing"
+)
+
+func EverySecond[T any](x []T) iter.Seq[T] {
+	return func(yield func(T) bool) {
+		for i := 0; i < len(x); i += 2 {
+			if !yield(x[i]) {
+				return
+			}
+		}
+	}
+}
+
+func TestRangefunc(t *testing.T) {
+	x := []int{1, 2, 3, 4, 5}
+	y := []int{}
+	for it := range EverySecond(x) {
+		y = append(y, it)
+	}
+	if !slices.Equal(y, []int{1, 3, 5}) {
+		t.Errorf("unexpected y: %v", y)
+	}
+}

test/goexperiment/test_repo/go.mod

@@ -0,0 +1 @@
+module github.com/please-build/please-rules/goexperiment-test

test/goexperiment/test_repo/plugins/BUILD_FILE

@@ -0,0 +1,4 @@
+plugin_repo(
+    name = "go",
+    revision = "master",
+)

test/goexperiment/test_repo/third_party/go/BUILD_FILE

@@ -0,0 +1,3 @@
+go_stdlib(
+    name = "std",
+)