cmd/go: include simd bridge package in compiled test imports

It looks like a missing logic which breaks a very simple hello world
simd program. To reproduce: create a new directory, `go mod init main`,
write a very simple main.go that imports simd/archsimd, and then open
it with vscode+gopls, then cmd/go will panic:

Error loading workspace: packages.Load error: err: exit status 2: stderr: panic: runtime error: index out of range [0] with length 0

This CL fixes that.

Change-Id: I03706a12dd0d8e2351494abe95265e4fc7672e48
Reviewed-on: https://go-review.googlesource.com/c/go/+/788281
LUCI-TryBot-Result: golang-scoped@luci-project-accounts.iam.gserviceaccount.com <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: David Chase <drchase@google.com>

src/cmd/go/internal/load/test.go

diff --git a/src/cmd/go/internal/load/test.go b/src/cmd/go/internal/load/test.go
index 44e1c2a..8453cb2 100644
--- a/src/cmd/go/internal/load/test.go
+++ b/src/cmd/go/internal/load/test.go
@@ -117,10 +117,6 @@
 	stk.Push(ImportInfo{Pkg: p.ImportPath + " (test)"})
 	rawTestImports := str.StringList(p.TestImports)
 
-	if hasSimd := hasSimd(p.TestImports); hasSimd {
-		p.TestImports = append(p.TestImports, SimdBridgePkg)
-	}
-
 	for i, path := range p.TestImports {
 		p1, err := loadImport(ld, ctx, opts, pre, path, p.Dir, p, &stk, p.Internal.Build.TestImportPos[path], ResolveImport)
 		if err != nil && ptestErr == nil {
@@ -133,6 +129,20 @@
 		p.TestImports[i] = p1.ImportPath
 		imports = append(imports, p1)
 	}
+
+	var ptestCompiledImports []string
+	if hasSimd := hasSimd(p.TestImports); hasSimd {
+		p1, err := loadImport(ld, ctx, opts, pre, SimdBridgePkg, p.Dir, p, &stk, nil, ResolveImport|allowSimdInternalBridge)
+		if err != nil && ptestErr == nil {
+			ptestErr = err
+			incomplete = true
+		}
+		if p1.Incomplete {
+			incomplete = true
+		}
+		imports = append(imports, p1)
+		ptestCompiledImports = append(ptestCompiledImports, p1.ImportPath)
+	}
 	var err error
 	p.TestEmbedFiles, testEmbed, err = resolveEmbed(p.Dir, p.TestEmbedPatterns)
 	if err != nil {
@@ -151,10 +161,6 @@
 	var pxtestIncomplete bool
 	rawXTestImports := str.StringList(p.XTestImports)
 
-	if hasSimd := hasSimd(p.XTestImports); hasSimd {
-		p.XTestImports = append(p.XTestImports, SimdBridgePkg)
-	}
-
 	for i, path := range p.XTestImports {
 		p1, err := loadImport(ld, ctx, opts, pre, path, p.Dir, p, &stk, p.Internal.Build.XTestImportPos[path], ResolveImport)
 		if err != nil && pxtestErr == nil {
@@ -170,6 +176,19 @@
 		}
 		p.XTestImports[i] = p1.ImportPath
 	}
+
+	var pxtestCompiledImports []string
+	if hasSimd := hasSimd(p.XTestImports); hasSimd {
+		p1, err := loadImport(ld, ctx, opts, pre, SimdBridgePkg, p.Dir, p, &stk, nil, ResolveImport|allowSimdInternalBridge)
+		if err != nil && pxtestErr == nil {
+			pxtestErr = err
+		}
+		if p1.Incomplete {
+			pxtestIncomplete = true
+		}
+		ximports = append(ximports, p1)
+		pxtestCompiledImports = append(pxtestCompiledImports, p1.ImportPath)
+	}
 	p.XTestEmbedFiles, xtestEmbed, err = resolveEmbed(p.Dir, p.XTestEmbedPatterns)
 	if err != nil && pxtestErr == nil {
 		pxtestErr = &PackageError{
@@ -210,6 +229,12 @@
 		ptest.Imports = str.StringList(p.TestImports, p.Imports)
 		ptest.Internal.Imports = append(imports, p.Internal.Imports...)
 		ptest.Internal.RawImports = str.StringList(rawTestImports, p.Internal.RawImports)
+		ptest.Internal.CompiledImports = slices.Clone(p.Internal.CompiledImports)
+		for _, path := range ptestCompiledImports {
+			if !slices.Contains(ptest.Internal.CompiledImports, path) {
+				ptest.Internal.CompiledImports = append(ptest.Internal.CompiledImports, path)
+			}
+		}
 		ptest.Internal.ForceLibrary = true
 		ptest.Internal.BuildInfo = nil
 		ptest.Internal.Build = new(build.Package)
@@ -258,8 +283,9 @@
 					ImportPos:  p.Internal.Build.XTestImportPos,
 					Directives: p.Internal.Build.XTestDirectives,
 				},
-				Imports:    ximports,
-				RawImports: rawXTestImports,
+				Imports:         ximports,
+				RawImports:      rawXTestImports,
+				CompiledImports: pxtestCompiledImports,
 
 				Asmflags:       p.Internal.Asmflags,
 				Gcflags:        p.Internal.Gcflags,