test: add go highlight test

tests/syntax-tests/source/Go/main.go

@@ -0,0 +1,81 @@
+// The hugeparam command identifies by-value parameters that are larger than n bytes.
+//
+// Example:
+//	$ ./hugeparams encoding/xml
+package main
+
+import (
+	"flag"
+	"fmt"
+	"go/ast"
+	"go/token"
+	"go/types"
+	"log"
+
+	"golang.org/x/tools/go/loader"
+)
+
+//!+
+var bytesFlag = flag.Int("bytes", 48, "maximum parameter size in bytes")
+
+var sizeof = (&types.StdSizes{8, 8}).Sizeof // the sizeof function
+
+func PrintHugeParams(fset *token.FileSet, info *types.Info, files []*ast.File) {
+	checkTuple := func(descr string, tuple *types.Tuple) {
+		for i := 0; i < tuple.Len(); i++ {
+			v := tuple.At(i)
+			if sz := sizeof(v.Type()); sz > int64(*bytesFlag) {
+				fmt.Printf("%s: %q %s: %s = %d bytes\n",
+					fset.Position(v.Pos()),
+					v.Name(), descr, v.Type(), sz)
+			}
+		}
+	}
+	checkSig := func(sig *types.Signature) {
+		checkTuple("parameter", sig.Params())
+		checkTuple("result", sig.Results())
+	}
+	for _, file := range files {
+		ast.Inspect(file, func(n ast.Node) bool {
+			switch n := n.(type) {
+			case *ast.FuncDecl:
+				checkSig(info.Defs[n.Name].Type().(*types.Signature))
+			case *ast.FuncLit:
+				checkSig(info.Types[n.Type].Type.(*types.Signature))
+			}
+			return true
+		})
+	}
+}
+
+//!-
+
+func main() {
+	flag.Parse()
+
+	// The loader loads a complete Go program from source code.
+	var conf loader.Config
+	_, err := conf.FromArgs(flag.Args(), false)
+	if err != nil {
+		log.Fatal(err) // command syntax error
+	}
+	lprog, err := conf.Load()
+	if err != nil {
+		log.Fatal(err) // load error
+	}
+
+	for _, info := range lprog.InitialPackages() {
+		PrintHugeParams(lprog.Fset, &info.Info, info.Files)
+	}
+}
+
+/*
+//!+output
+% ./hugeparam encoding/xml
+/go/src/encoding/xml/marshal.go:167:50: "start" parameter: encoding/xml.StartElement = 56 bytes
+/go/src/encoding/xml/marshal.go:734:97: "" result: encoding/xml.StartElement = 56 bytes
+/go/src/encoding/xml/marshal.go:761:51: "start" parameter: encoding/xml.StartElement = 56 bytes
+/go/src/encoding/xml/marshal.go:781:68: "start" parameter: encoding/xml.StartElement = 56 bytes
+/go/src/encoding/xml/xml.go:72:30: "" result: encoding/xml.StartElement = 56 bytes
+//!-output
+*/