github.com/ianlancetaylor/demangle v0.0.0-20250417193237-f615e6bd150b: Option

Clean-room public code sample — generation instructions

Write a brand-new, minimal, self-contained code sample in this clean-room directory.
Do not copy, paraphrase, or reference any existing project source. Work only from this spec.

A csx.json manifest scaffold already exists. Do not recreate it from memory. Preserve its case.goal, packages and symbols; fill its empty case.contract with exact assertions and correct its environment, commands and verifierAdapter for the files you generate.

Goal: verify github.com/ianlancetaylor/demangle.Option in pkg:golang/github.com/ianlancetaylor/demangle@v0.0.0-20250417193237-f615e6bd150b
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/ianlancetaylor/demangle@v0.0.0-20250417193237-f615e6bd150b
Demonstrate these symbols/APIs:
  - github.com/ianlancetaylor/demangle.Option

Rules:
  - One focused purpose; the smallest project that proves the goal.
  - Include a contract test (test/contract.*) that runs OFFLINE and exits 0 exactly when the goal behavior works.
  - Pin every dependency with a lockfile so resolution is reproducible.
  - No secrets, credentials, or tokens. No real URLs (only example.com or localhost). No absolute paths.
  - No personal names, emails, company names, or project identifiers of any kind.
  - No binaries and no generated output (node_modules, dist, target, venv, .git, .env).
  - Keep it under 200 files and 256KB packed.

{"case":{"caseId":"case:sha256:9094ea593ba0290fb59a278ec8203651cac05798822ffd671ecd10f2aa549ba9","contract":["demangle.NoParams omits function parameter types and clone suffixes in demangle.ToString","demangle.NoTemplateParams omits template arguments in demangle.ToString","demangle.NoClones strips compiler clone suffixes while preserving parameter types in demangle.ToString","demangle.Verbose expands standard C++ library substitutions in demangle.ToString","demangle.LLVMStyle formats nested template closing brackets without an extra space in demangle.ToString","demangle.MaxLength returns an Option that truncates demangled output to 2^pow characters","Multiple demangle.Option values can be passed to demangle.ToString and demangle.ToAST"],"goal":"verify github.com/ianlancetaylor/demangle.Option in pkg:golang/github.com/ianlancetaylor/demangle@v0.0.0-20250417193237-f615e6bd150b","kind":"HOW","packages":["pkg:golang/github.com/ianlancetaylor/demangle@v0.0.0-20250417193237-f615e6bd150b"],"schemaVersion":1,"symbols":["github.com/ianlancetaylor/demangle.Option"]},"contractCommand":["go","run","./test"],"environment":{"arch":"x64","compiler":"go","compilerVersion":"1.26.6","distro":"ubuntu","ecosystem":"golang","language":"go","languageVersion":"1.26.6","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"go","packageManagerVersion":"1.26.6","runtime":"go","runtimeVersion":"1.26.6","schemaVersion":1},"license":"MIT-0","packages":["pkg:golang/github.com/ianlancetaylor/demangle@v0.0.0-20250417193237-f615e6bd150b"],"schemaVersion":1,"subject":"pkg:golang/github.com/ianlancetaylor/demangle@v0.0.0-20250417193237-f615e6bd150b","symbols":["github.com/ianlancetaylor/demangle.Option"],"verifierAdapter":"golang@1"}

module sample

go 1.26.6

require github.com/ianlancetaylor/demangle v0.0.0-20250417193237-f615e6bd150b

github.com/ianlancetaylor/demangle v0.0.0-20250417193237-f615e6bd150b h1:ogbOPx86mIhFy764gGkqnkFC8m5PJA7sPzlk9ppLVQA=
github.com/ianlancetaylor/demangle v0.0.0-20250417193237-f615e6bd150b/go.mod h1:gx7rwoVhcfuVKG5uya9Hs3Sxj7EIvldVofAWIUtGouw=

package main

import (
	"fmt"
	"os"

	"github.com/ianlancetaylor/demangle"
)

func main() {
	opts := []demangle.Option{
		demangle.NoParams,
		demangle.NoTemplateParams,
		demangle.NoClones,
		demangle.Verbose,
		demangle.LLVMStyle,
		demangle.MaxLength(6),
	}

	symbol := "_Z4calcIiEvT_.clone.1"
	for _, opt := range opts {
		out, err := demangle.ToString(symbol, opt)
		if err != nil {
			fmt.Fprintf(os.Stderr, "demangle failed: %v\n", err)
			os.Exit(1)
		}
		fmt.Println(out)
	}
}

{
  "schemaVersion": 1,
  "goal": "verify github.com/ianlancetaylor/demangle.Option in pkg:golang/github.com/ianlancetaylor/demangle@v0.0.0-20250417193237-f615e6bd150b",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/ianlancetaylor/demangle@v0.0.0-20250417193237-f615e6bd150b"
  ],
  "symbols": [
    "github.com/ianlancetaylor/demangle.Option"
  ]
}

package main

import (
	"fmt"
	"os"

	"github.com/ianlancetaylor/demangle"
)

func main() {
	// 1. demangle.NoParams omits function parameter types and clone suffixes in demangle.ToString
	var optNoParams demangle.Option = demangle.NoParams
	gotNoParams, err := demangle.ToString("_Z7computeid.clone.2", optNoParams)
	if err != nil || gotNoParams != "compute" {
		fmt.Fprintf(os.Stderr, "NoParams failed: got (%q, %v), want (\"compute\", nil)\n", gotNoParams, err)
		os.Exit(1)
	}

	// 2. demangle.NoTemplateParams omits template arguments in demangle.ToString
	var optNoTemplate demangle.Option = demangle.NoTemplateParams
	gotNoTemplate, err := demangle.ToString("_Z4evalIiEvT_", optNoTemplate)
	if err != nil || gotNoTemplate != "void eval(int)" {
		fmt.Fprintf(os.Stderr, "NoTemplateParams failed: got (%q, %v), want (\"void eval(int)\", nil)\n", gotNoTemplate, err)
		os.Exit(1)
	}

	// 3. demangle.NoClones strips compiler clone suffixes while preserving parameter types in demangle.ToString
	var optNoClones demangle.Option = demangle.NoClones
	gotNoClones, err := demangle.ToString("_Z7computeid.clone.2", optNoClones)
	if err != nil || gotNoClones != "compute(int, double)" {
		fmt.Fprintf(os.Stderr, "NoClones failed: got (%q, %v), want (\"compute(int, double)\", nil)\n", gotNoClones, err)
		os.Exit(1)
	}

	// 4. demangle.Verbose expands standard C++ library substitutions in demangle.ToString
	var optVerbose demangle.Option = demangle.Verbose
	gotVerbose, err := demangle.ToString("_Z5printSs", optVerbose)
	wantVerbose := "print(std::basic_string<char, std::char_traits<char>, std::allocator<char> >)"
	if err != nil || gotVerbose != wantVerbose {
		fmt.Fprintf(os.Stderr, "Verbose failed: got (%q, %v), want (%q, nil)\n", gotVerbose, err, wantVerbose)
		os.Exit(1)
	}

	// 5. demangle.LLVMStyle formats nested template closing brackets without an extra space in demangle.ToString
	var optLLVM demangle.Option = demangle.LLVMStyle
	gotLLVM, err := demangle.ToString("_Z5printSs", optVerbose, optLLVM)
	wantLLVM := "print(std::basic_string<char, std::char_traits<char>, std::allocator<char>>)"
	if err != nil || gotLLVM != wantLLVM {
		fmt.Fprintf(os.Stderr, "LLVMStyle failed: got (%q, %v), want (%q, nil)\n", gotLLVM, err, wantLLVM)
		os.Exit(1)
	}

	// 6. demangle.MaxLength returns an Option that truncates demangled output to 2^pow characters
	var optMaxLen demangle.Option = demangle.MaxLength(3)
	gotTrunc, err := demangle.ToString("_Z7computeid", optMaxLen)
	if err != nil || len(gotTrunc) != 8 || gotTrunc != "compute(" {
		fmt.Fprintf(os.Stderr, "MaxLength(3) failed: got (%q, %v), want 8-char \"compute(\"\n", gotTrunc, err)
		os.Exit(1)
	}

	// 7. Multiple demangle.Option values can be passed to demangle.ToString and demangle.ToAST
	combinedOpts := []demangle.Option{demangle.NoParams, demangle.NoTemplateParams}
	gotCombined, err := demangle.ToString("_Z4evalIiEvT_", combinedOpts...)
	if err != nil || gotCombined != "eval" {
		fmt.Fprintf(os.Stderr, "Combined options failed: got (%q, %v), want (\"eval\", nil)\n", gotCombined, err)
		os.Exit(1)
	}

	astNode, err := demangle.ToAST("_Z4evalIiEvT_", demangle.NoTemplateParams)
	if err != nil || astNode == nil {
		fmt.Fprintf(os.Stderr, "ToAST with Option failed: got (%v, %v)\n", astNode, err)
		os.Exit(1)
	}
}