rowserrcheck false positive when deferred Close() is wrapped in a func

[stevendanna]

rowserrcheck appears to produce a false positive when a deferred rows.Close() is wrapped in a func. This is perhaps similar to #1670, but occurs even on versions that should include that fix.

The false positive can be reproduced by the following example:

func Bug(db *sql.DB) {
        rows, err := db.Query("select 1")
        if err != nil {
                panic(err)
        }

        defer func() { _ = rows.Close() }()
        for rows.Next() {
                fmt.Println("new rows")
        }

        if err := rows.Err(); err != nil {
                panic(err)
        }
}

This example will report the following error, despite rows.Err() clearly being checked.

repro.go:9:23: rows.Err must be checked (rowserrcheck)
        rows, err := db.Query("select 1")

Interestingly, if defer func() { _ = rows.Close() }() is changed to defer rows.Close(), the false positive goes away.

---

• Yes, I'm using a binary release within 2 latest major releases. Only such installations are supported.
• Yes, I've searched similar issues on GitHub and didn't find any.
• Yes, I've included all information below (version, config, etc).

Please include the following information:

Version of golangci-lint

$ golangci-lint --version
golangci-lint has version 1.37.1 built from b39dbcd on 2021-02-22T04:33:13Z

Config file

$ cat .golangci.yml

Go environment

$ go version && go env
go version go1.15.8 darwin/amd64
GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/Users/ssd/Library/Caches/go-build"
GOENV="/Users/ssd/Library/Application Support/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOINSECURE=""
GOMODCACHE="/Users/ssd/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="darwin"
GOPATH="/Users/ssd/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/Cellar/go/1.15.8/libexec"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/Cellar/go/1.15.8/libexec/pkg/tool/darwin_amd64"
GCCGO="gccgo"
AR="ar"
CC="clang"
CXX="clang++"
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 -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/b4/2b8v9mcx5x9d64k7q3m0fz_40000gp/T/go-build620955549=/tmp/go-build -gno-record-gcc-switches -fno-common"```

</details>

<details><summary>Verbose output of running</summary>

```console
$ golangci-lint cache clean
$ golangci-lint run --disable-all --enable rowserrcheck -v repro.go
INFO [config_reader] Config search paths: [./ /Users/ssd/tmp /Users/ssd /Users /] 
INFO [lintersdb] Active 1 linters: [rowserrcheck] 
INFO [loader] Go packages loading at mode 575 (compiled_files|deps|exports_file|files|imports|name|types_sizes) took 246.449759ms 
INFO [runner/filename_unadjuster] Pre-built 0 adjustments in 194.581µs 
INFO [linters context/goanalysis] analyzers took 4.398224ms with top 10 stages: buildssa: 4.378385ms, rowserrcheck: 19.839µs 
INFO [runner] Processors filtering stat (out/in): exclude-rules: 1/1, max_same_issues: 1/1, severity-rules: 1/1, path_prettifier: 1/1, filename_unadjuster: 1/1, identifier_marker: 1/1, max_per_file_from_linter: 1/1, cgo: 1/1, nolint: 1/1, path_prefixer: 1/1, sort_results: 1/1, skip_files: 1/1, autogenerated_exclude: 1/1, exclude: 1/1, uniq_by_line: 1/1, diff: 1/1, max_from_linter: 1/1, source_code: 1/1, path_shortener: 1/1, skip_dirs: 1/1 
INFO [runner] processing took 236.307µs with stages: nolint: 66.688µs, path_prettifier: 41.128µs, autogenerated_exclude: 40.819µs, source_code: 35.318µs, identifier_marker: 24.321µs, exclude-rules: 10.103µs, skip_dirs: 9.009µs, cgo: 2.244µs, max_same_issues: 1.341µs, uniq_by_line: 1.197µs, path_shortener: 1.063µs, max_from_linter: 715ns, filename_unadjuster: 699ns, diff: 357ns, max_per_file_from_linter: 333ns, exclude: 241ns, severity-rules: 219ns, skip_files: 210ns, sort_results: 173ns, path_prefixer: 129ns 
INFO [runner] linters took 62.858379ms with stages: rowserrcheck: 62.55521ms 
repro.go:9:23: rows.Err must be checked (rowserrcheck)
        rows, err := db.Query("select 1")
                             ^
INFO File cache stats: 1 entries of total size 280B 
INFO Memory: 5 samples, avg is 72.6MB, max is 73.3MB 
INFO Execution took 322.928163ms 

[boring-cyborg]

Hey, thank you for opening your first Issue ! 🙂 If you would like to contribute we have a guide for contributors.

[ldez]

Can you reproduce this issue with just rowserrcheck? If so, it's best to raise an issue to the upstream repository, and then we can bump the version when it's fixed.

[stevendanna]

Done: jingyugao/rowserrcheck#16

[ldez]

Fixed by #1843