Comma in exclude pattern leads to unexpected results

[xrstf]

Bug Report

I tried to configure an exclude pattern to get rid of some goconst errors. These errors take the form of

string `get` has 12 occurrences, make it a constant

So I made an exclude filter like this:

issues:
  exclude:
  - "string `get` has [0-9]+ occurences, make it a constant"

and then noticed that all goconst errors disappeared. After adding some debugging statements to the code, I could see that the final assembled regex is

(?i)(string `get` has [0-9]+ occurences| make it a constant|Error return value of .((os\.)?std(out|err)\..*|.*Close|.*Flush|os\.Remove(All)?|.*printf?|os\.(Un)?Setenv). is not checked|(comment on exported (method|function|type|const)|should have( a package)? comment|comment should be of the form)|func name will be used as test\.Test.* by other packages, and that stutters; consider calling this|(possible misuse of unsafe.Pointer|should have signature)|ineffective break statement. Did you mean to break out of the outer loop|Use of unsafe calls should be audited|Subprocess launch(ed with variable|ing should be audited)|G104|(Expect directory permissions to be 0750 or less|Expect file permissions to be 0600 or less)|Potential file inclusion via variable)

Notice how the comma turned the exclusion pattern into two distinct elements. The documentation in the readme just says

List of regexps of issue texts to exclude, empty list by default.

I don't really know why this is tagged as a mapstructure in the code, but right now the behaviour or the documentation is misleading.

Version of golangci-lint:

1.17.1 or master branch

Config file: cat .golangci.yml

linters:
  enable:
   - goconst
  disable-all: true

issues:
  exclude:
  - iamnotarealstring, make it a constant

Go environment: go version && go env

go version go1.13 linux/amd64
GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/xrstf/.cache/go-build"
GOENV="/home/xrstf/.config/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/home/xrstf/gospace"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"
GCCGO="gccgo"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build282403496=/tmp/go-build -gno-record-gcc-switches"

cc @alvaroaleman

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[ldez]

The problem is related to the custom parsing of slice flags:

golangci-lint/pkg/commands/executor.go

Line 122 in 5d10450

fixSlicesFlags(e.runCmd.Flags())

golangci-lint/pkg/commands/run.go

Lines 298 to 319 in 5d10450

	func fixSlicesFlags(fs *pflag.FlagSet) {
	// It's a dirty hack to set flag.Changed to true for every string slice flag.
	// It's necessary to merge config and command-line slices: otherwise command-line
	// flags will always overwrite ones from the config.
	fs.VisitAll(func(f *pflag.Flag) {
	if f.Value.Type() != "stringSlice" {
	return
	}
	s, err := fs.GetStringSlice(f.Name)
	if err != nil {
	return
	}
	if s == nil { // assume that every string slice flag has nil as the default
	return
	}
	// calling Set sets Changed to true: next Set calls will append, not overwrite
	_ = f.Value.Set(strings.Join(s, ","))
	})
	}