for _, v := range vectors {
		var p parser
		got := p.parseNumeric([]byte(v.in))
		ok := (p.err == nil)
		if ok != v.ok {
			if v.ok {
				t.Errorf("parseNumeric(%q): got parsing failure, want success", v.in)
			} else {
				t.Errorf("parseNumeric(%q): got parsing success, want failure", v.in)
			}
		}
		if ok && got != v.want {
			t.Errorf("parseNumeric(%q): got %d, want %d", v.in, got, v.want)
		}
	}
}

func newParser(goarch string) *Parser {
	architecture, ctxt := setArch(goarch)
	return NewParser(ctxt, architecture, nil)
}

// tryParse executes parse func in panicOnError=true context.
// parse is expected to call any parsing methods that may panic.
// Returns error gathered from recover; nil if no parse errors occurred.
//
// For unexpected panics, calls t.Fatal.
func tryParse(t *testing.T, parse func()) (err error) {
	panicOnError = true

	s.scan()
	for ; len(s.token) >= min; s.scan() {
		end = s.end
	}
	return end
}

// Parse parses the given BCP 47 string and returns a valid Tag. If parsing
// failed it returns an error and any part of the tag that could be parsed.
// If parsing succeeded but an unknown value was found, it returns
// ValueError. The Tag returned in this case is just stripped of the unknown

	if err != nil {
		return nil, fmt.Errorf("error parsing %s: %v", name, err)
	}
	defer of.Close()

	return b.openMachOCommon(name, of, start, limit, offset)
}

func (b *binrep) openELF(name string, start, limit, offset uint64, relocationSymbol string) (plugin.ObjFile, error) {
	ef, err := elfOpen(name)
	if err != nil {
		return nil, fmt.Errorf("error parsing %s: %v", name, err)
	}
	defer ef.Close()

	}
	if err != nil {
		return nil, nil, err
	}

	f, err = modfile.Parse(gomod, data, fix)
	if err != nil {
		// Errors returned by modfile.Parse begin with file:line.
		return nil, nil, fmt.Errorf("errors parsing %s:\n%w", gomod, err)
	}
	if f.Go != nil && gover.Compare(f.Go.Version, gover.Local()) > 0 {
		toolchain := ""
		if f.Toolchain != nil {
			toolchain = f.Toolchain.Name
		}

			r, err := regexp.Compile(env)
			if err != nil {
				return fmt.Errorf("parsing $CGO_%s_ALLOW: %v", name, err)
			}
			allow = r
		}
		if env := cfg.Getenv("CGO_" + name + "_DISALLOW"); env != "" {
			r, err := regexp.Compile(env)
			if err != nil {
				return fmt.Errorf("parsing $CGO_%s_DISALLOW: %v", name, err)
			}
			disallow = r
		}
	}

Args:

cp go.mod.orig go.mod
go mod edit -require golang.org/x/text@14c0d48ead0c
cd outside
! go list -m golang.org/x/text
stderr 'go: example.com@v0.0.0 \(replaced by \./\.\.\): parsing ..[/\\]go.mod: '$WORK'[/\\]gopath[/\\]src[/\\]go.mod:5: require golang.org/x/text: version "14c0d48ead0c" invalid: must be of the form v1.2.3'
cd ..
go list -m golang.org/x/text

		i := strings.IndexRune(name, '=')
		if i > 0 {
			name, value = name[:i], name[i+1:]
		}
		tokens := Tokenize(name)
		if len(tokens) != 1 || tokens[0].ScanToken != scanner.Ident {
			fmt.Fprintf(os.Stderr, "asm: parsing -D: %q is not a valid identifier name\n", tokens[0])
			flags.Usage()
		}
		macros[name] = &Macro{
			name:   name,
			args:   nil,
			tokens: Tokenize(value),
		}
	}
	return macros
}

	pList.Firstpc, ok = parser.Parse()
	if !ok || failed {
		t.Errorf("asm: %s assembly failed", goarch)
		return
	}
	output := strings.Split(testOut.String(), "\n")

	// Reconstruct expected output by independently "parsing" the input.
	data, err := os.ReadFile(input)
	if err != nil {
		t.Error(err)
		return
	}
	lineno := 0
	seq := 0
	hexByLine := map[string]string{}
	lines := strings.SplitAfter(string(data), "\n")
Diff:

		if err != nil {
			p.errorf("parsing left shift amount: %s", err)
		}
		num = int16(amount)
	} else if p.peek() == '[' {
		// parses an element: [Index]
		p.get('[')
		tok := p.get(scanner.Int)
		index, err := strconv.ParseInt(tok.String(), 10, 16)
		p.get(']')
		if err != nil {
			p.errorf("parsing element index: %s", err)
		}
		isIndex = true
		isAmount = false