build: preserve main package identity for test builds

dev/test_std_buildmodes.sh

@@ -96,10 +96,12 @@ for mode in c-shared c-archive; do
 			fi
 			import_path="${import_paths[$i]}"
 			stem="${stems[$i]}"
-			test_main_pkg="${import_path}.test"
 			runner_base="${work_dir}/runner-${i}"
 			echo "==> ${test_pkgs[$i]}: run ${mode}"
-			runner_cflags=("-DGO_TEST_PACKAGE=\"${test_main_pkg}\"")
+			# Test-main packages keep the Go package identity "main". The
+			# output library is still named after its import path (for example,
+			# libtar.test), but its entry points are main.init and main.main.
+			runner_cflags=("-DGO_TEST_MAIN_PACKAGE=\"main\"")
 			if [[ "${mode}" == c-shared ]]; then
 				runner_cflags+=("-DGO_C_SHARED=1")
 			fi

dev/test_std_buildmodes/runner.c

@@ -1,5 +1,5 @@
-#ifndef GO_TEST_PACKAGE
-#error GO_TEST_PACKAGE must name the generated Go test main package
+#ifndef GO_TEST_MAIN_PACKAGE
+#error GO_TEST_MAIN_PACKAGE must name the generated Go test main package
 #endif
 
 #include <string.h>
@@ -10,8 +10,8 @@
 #define GO_SYMBOL(name) __asm__(name)
 #endif
 
-extern void llgo_test_init(void) GO_SYMBOL(GO_TEST_PACKAGE ".init");
-extern void llgo_test_run(void) GO_SYMBOL(GO_TEST_PACKAGE ".main");
+extern void llgo_test_init(void) GO_SYMBOL(GO_TEST_MAIN_PACKAGE ".init");
+extern void llgo_test_run(void) GO_SYMBOL(GO_TEST_MAIN_PACKAGE ".main");
 extern int __llgo_argc;
 extern char **__llgo_argv;
 

internal/build/build.go

@@ -520,11 +520,14 @@ func Build(inv Invocation) ([]Package, error) {
 		defer syntaxErrMu.Unlock()
 		return syntaxErr
 	}
-	dedup.SetPreload(func(pkg *types.Package, files []*ast.File) {
-		if llruntime.SkipToBuild(pkg.Path()) {
+	dedup.SetPreload(func(pkg *packages.Package) {
+		if llruntime.SkipToBuild(pkg.PkgPath) {
 			return
 		}
-		if err := cl.ParsePkgSyntaxWithOptions(prog, cfg.Fset, pkg, files, preloadOptions); err != nil {
+		if pkg.Name == "main" && pkg.ForTest != "" {
+			pkg.Types.Scope().Insert(types.NewConst(0, pkg.Types, abi.ForTestMarker, types.Typ[types.UntypedBool], constant.MakeBool(true)))
+		}
+		if err := cl.ParsePkgSyntaxWithOptions(prog, cfg.Fset, pkg.Types, pkg.Syntax, preloadOptions); err != nil {
 			recordSyntaxErr(err)
 		}
 	})
@@ -888,9 +891,6 @@ func filterTestPackages(initial []*packages.Package, outFile string) ([]*package
 		if needLink(pkg, ModeTest) {
 			filtered = append(filtered, pkg)
 		}
-		if pkg.Types != nil && pkg.Types.Name() == "main" {
-			pkg.Types.SetName("main.test")
-		}
 	}
 	if len(filtered) > 1 && outFile != "" {
 		return nil, fmt.Errorf("cannot use -o flag with multiple packages")
@@ -1784,8 +1784,8 @@ func cSharedExportArgs(ctx *context, pkgs []*aPackage) []string {
 			}
 		}
 		if ctx.mode == ModeTest && pkg.Package != nil && pkg.Name == "main" && strings.HasSuffix(pkg.PkgPath, ".test") {
-			exports[pkg.PkgPath+".init"] = none{}
-			exports[pkg.PkgPath+".main"] = none{}
+			exports["main.init"] = none{}
+			exports["main.main"] = none{}
 		}
 	}
 	names := make([]string, 0, len(exports))

internal/build/build_test.go

@@ -811,25 +811,6 @@ func TestFilterTestPackages(t *testing.T) {
 		}
 	})
 
-	t.Run("rename main package", func(t *testing.T) {
-		mainPkg := pkg("example.com/cmd")
-		mainPkg.Types = types.NewPackage(mainPkg.ID, "main")
-		initial := []*packages.Package{
-			mainPkg,
-			pkg("example.com/cmd.test"),
-		}
-		filtered, err := filterTestPackages(initial, "")
-		if err != nil {
-			t.Fatalf("filterTestPackages returned unexpected error: %v", err)
-		}
-		if len(filtered) != 1 || filtered[0].ID != "example.com/cmd.test" {
-			t.Fatalf("filtered = %#v, want only example.com/cmd.test", filtered)
-		}
-		if got := mainPkg.Types.Name(); got != "main.test" {
-			t.Fatalf("main package name = %q, want %q", got, "main.test")
-		}
-	})
-
 	t.Run("multiple test packages with output file", func(t *testing.T) {
 		initial := []*packages.Package{
 			pkg("a.test"),
@@ -1378,7 +1359,7 @@ func TestCSharedExportArgsKeepsTestMain(t *testing.T) {
 		mode:      ModeTest,
 		buildConf: &Config{BuildMode: BuildModeCShared, Goos: "linux"},
 	}
-	if got, want := strings.Join(cSharedExportArgs(ctx, pkgs), " "), "-Wl,--undefined=example.com/p.test.init -Wl,--undefined=example.com/p.test.main"; got != want {
+	if got, want := strings.Join(cSharedExportArgs(ctx, pkgs), " "), "-Wl,--undefined=main.init -Wl,--undefined=main.main"; got != want {
 		t.Fatalf("test main cSharedExportArgs = %q, want %q", got, want)
 	}
 }

internal/packages/load.go

@@ -90,7 +90,7 @@ type aDeduper struct {
 	cache     sync.Map
 	checked   sync.Map
 	setpath   func(path string, name string) string
-	preload   func(pkg *types.Package, syntax []*ast.File)
+	preload   func(pkg *packages.Package)
 	llgoFiles map[string][]string
 }
 
@@ -100,7 +100,7 @@ func NewDeduper() Deduper {
 	return &aDeduper{}
 }
 
-func (p Deduper) SetPreload(fn func(pkg *types.Package, syntax []*ast.File)) {
+func (p Deduper) SetPreload(fn func(pkg *packages.Package)) {
 	p.preload = fn
 }
 
@@ -458,7 +458,7 @@ func (tc *typecheckContext) typecheckPackage(pkg *Package) {
 	})
 
 	if tc.dedup != nil && tc.dedup.preload != nil {
-		tc.dedup.preload(pkg.Types, pkg.Syntax)
+		tc.dedup.preload(pkg)
 	}
 
 	typeConf := &types.Config{

ssa/abi/abi.go

@@ -286,14 +286,15 @@ func typeArgString(t types.Type) string {
 
 const (
 	PatchPathPrefix = env.LLGoRuntimePkg + "/internal/lib/"
+	ForTestMarker   = "@ForTest"
 )
 
 // PathOf returns the package path of the specified package.
 func PathOf(pkg *types.Package) string {
 	if pkg == nil {
 		return ""
 	}
-	if pkg.Name() == "main" {
+	if pkg.Name() == "main" && pkg.Scope().Lookup(ForTestMarker) == nil {
 		return "main"
 	}
 	return strings.TrimPrefix(pkg.Path(), PatchPathPrefix)

test/go/linkname/demo_test.go

@@ -0,0 +1,25 @@
+package main_test
+
+import (
+	"testing"
+	_ "unsafe"
+)
+
+//go:linkname demo github.com/xgo-dev/llgo/test/go/linkname.demo
+func demo() int
+
+func xdemo1() int {
+	return 44
+}
+
+//go:linkname xdemo2 github.com/xgo-dev/llgo/test/go/linkname_test.xdemo1
+func xdemo2() int
+
+func TestLinknameFromExternalTestPackage(t *testing.T) {
+	if got := demo(); got != 42 {
+		t.Fatalf("external-test-to-main linkname = %d, want 42", got)
+	}
+	if got := xdemo2(); got != 44 {
+		t.Fatalf("external-test self linkname = %d, want 44", got)
+	}
+}

test/go/linkname/main.go

@@ -0,0 +1,18 @@
+package main
+
+import _ "unsafe"
+
+func main() {
+	main_demo()
+}
+
+func demo() int {
+	return 42
+}
+
+func demo2() int {
+	return 43
+}
+
+//go:linkname main_demo main.demo
+func main_demo() int

test/go/linkname/main_test.go

@@ -0,0 +1,31 @@
+package main
+
+import (
+	"testing"
+	_ "unsafe"
+)
+
+func TestLinknameFromSameTestPackage(t *testing.T) {
+	if got := demo(); got != 42 {
+		t.Fatalf("same-package linkname = %d, want 42", got)
+	}
+}
+
+func demo3() int {
+	return 42
+}
+
+//go:linkname demo4 github.com/xgo-dev/llgo/test/go/linkname.demo2
+func demo4() int
+
+//go:linkname demo5 github.com/xgo-dev/llgo/test/go/linkname.demo3
+func demo5() int
+
+func TestLinknameToMainPackage(t *testing.T) {
+	if got := demo4(); got != 43 {
+		t.Fatalf("test-to-main linkname = %d, want 43", got)
+	}
+	if got := demo5(); got != 42 {
+		t.Fatalf("test-to-main linkname = %d, want 42", got)
+	}
+}