all: implement sub-matches support (#363)

Fixes #28

analyzer/testdata/src/matching/file.go

@@ -1,6 +1,7 @@
 package matching
 
 func sink(args ...interface{}) {}
+func expensive()               {}
 
 func multiexpr() (int, int, int) {
 	sink(1, 1)         // want `\Qrepeated expression in list`
@@ -52,3 +53,74 @@ func rangeClause() {
 		}
 	}
 }
+
+func submatchContains() {
+	{
+		type Book struct {
+			AuthorID int
+		}
+		var books []Book
+		m := make(map[int][]Book)
+		for _, b := range books {
+			m[b.AuthorID] = append(m[b.AuthorID], b) // want `\Qm[b.AuthorID] contains b`
+		}
+	}
+
+	{
+		var b1 []byte
+		var b2 []byte
+		copy(b1, b2)
+		copy(b1[:], b2)    // want `\Qcopy() contains a slicing operation`
+		copy(b1, b2[:])    // want `\Qcopy() contains a slicing operation`
+		copy(b1[:], b2[:]) // want `\Qcopy() contains a slicing operation`
+	}
+
+	_ = func() error {
+		var err error
+		sink(err) // want `\Qsink(err) call not followed by return err`
+		return nil
+	}
+	_ = func() error {
+		var err error
+		sink(err)
+		return err
+	}
+	_ = func() error {
+		var err2 error
+		sink(err2) // want `\Qsink(err2) call not followed by return err2`
+		return nil
+	}
+	_ = func() error {
+		var err2 error
+		sink(err2)
+		return err2
+	}
+
+	for { // want `\Qexpensive call inside a loop`
+		expensive()
+	}
+	var cond bool
+	for { // want `\Qexpensive call inside a loop`
+		if cond {
+			expensive()
+		}
+	}
+	for {
+		if cond {
+		}
+	}
+	for { // want `\Qexpensive call inside a loop`
+		for { // want `\Qexpensive call inside a loop`
+			expensive()
+		}
+	}
+
+	{
+		type object struct {
+			val int
+		}
+		var objects []object
+		if objects != nil && objects[0].val != 0 { // want `\Qnil check may not be enough to access objects[0], check for len`
+		}
+	}
+}

analyzer/testdata/src/matching/rules.go

@@ -11,4 +11,24 @@ func testRules(m dsl.Matcher) {
 	m.Match(`range $x[:]`).
 		Where(m["x"].Type.Is(`[]$_`)).
 		Report(`redundant slicing of a range expression`)
+
+	m.Match(`$lhs = append($lhs, $x)`).
+		Where(m["lhs"].Contains(`$x`)).
+		Report(`$lhs contains $x`)
+
+	m.Match(`copy($*args)`).
+		Where(m["args"].Contains(`$_[:]`)).
+		Report(`copy() contains a slicing operation`)
+
+	m.Match(`sink($err); $x`).
+		Where(!m["x"].Contains(`return $err`) && m["err"].Type.Is(`error`)).
+		Report(`sink($err) call not followed by return $err`)
+
+	m.Match(`for { $*body }`).
+		Where(m["body"].Contains(`expensive()`)).
+		Report(`expensive call inside a loop`)
+
+	m.Match(`$x != nil && $y`).
+		Where(m["y"].Contains(`$x[0]`)).
+		Report(`nil check may not be enough to access $x[0], check for len`)
 }

go.mod

@@ -5,9 +5,9 @@ go 1.17
 require (
 	github.com/go-toolsmith/astcopy v1.0.0
 	github.com/google/go-cmp v0.5.6
-	github.com/quasilyte/go-ruleguard/dsl v0.3.13
+	github.com/quasilyte/go-ruleguard/dsl v0.3.14
 	github.com/quasilyte/go-ruleguard/rules v0.0.0-20211022131956-028d6511ab71
-	github.com/quasilyte/gogrep v0.0.0-20220104185649-039753a3dd32
+	github.com/quasilyte/gogrep v0.0.0-20220120141003-628d8b3623b5
 	golang.org/x/tools v0.1.9-0.20211228192929-ee1ca4ffc4da
 )
 

go.sum

@@ -12,11 +12,15 @@ github.com/quasilyte/go-ruleguard v0.3.1-0.20210203134552-1b5a410e1cc8/go.mod h1
 github.com/quasilyte/go-ruleguard/dsl v0.3.0/go.mod h1:KeCP03KrjuSO0H1kTuZQCWlQPulDV6YMIXmpQss17rU=
 github.com/quasilyte/go-ruleguard/dsl v0.3.13 h1:WmtzUkp28TMarzfBCogPf7plyI/2gsNsj8CgZ9ihPCM=
 github.com/quasilyte/go-ruleguard/dsl v0.3.13/go.mod h1:KeCP03KrjuSO0H1kTuZQCWlQPulDV6YMIXmpQss17rU=
+github.com/quasilyte/go-ruleguard/dsl v0.3.14 h1:diesHrFHZ6rxuFltuwiW7NRQaqUIypuSSmUulRCNuqM=
+github.com/quasilyte/go-ruleguard/dsl v0.3.14/go.mod h1:KeCP03KrjuSO0H1kTuZQCWlQPulDV6YMIXmpQss17rU=
 github.com/quasilyte/go-ruleguard/rules v0.0.0-20201231183845-9e62ed36efe1/go.mod h1:7JTjp89EGyU1d6XfBiXihJNG37wB2VRkd125Q1u7Plc=
 github.com/quasilyte/go-ruleguard/rules v0.0.0-20211022131956-028d6511ab71 h1:CNooiryw5aisadVfzneSZPswRWvnVW8hF1bS/vo8ReI=
 github.com/quasilyte/go-ruleguard/rules v0.0.0-20211022131956-028d6511ab71/go.mod h1:4cgAphtvu7Ftv7vOT2ZOYhC6CvBxZixcasr8qIOTA50=
 github.com/quasilyte/gogrep v0.0.0-20220104185649-039753a3dd32 h1:fJhpG5LYGnHZqUIDULZkvQKJfdtAefNrkoiGCezlr7g=
 github.com/quasilyte/gogrep v0.0.0-20220104185649-039753a3dd32/go.mod h1:wSEyW6O61xRV6zb6My3HxrQ5/8ke7NE2OayqCHa3xRM=
+github.com/quasilyte/gogrep v0.0.0-20220120141003-628d8b3623b5 h1:PDWGei+Rf2bBiuZIbZmM20J2ftEy9IeUCHA8HbQqed8=
+github.com/quasilyte/gogrep v0.0.0-20220120141003-628d8b3623b5/go.mod h1:wSEyW6O61xRV6zb6My3HxrQ5/8ke7NE2OayqCHa3xRM=
 github.com/yuin/goldmark v1.1.32/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
 github.com/yuin/goldmark v1.2.1/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
 github.com/yuin/goldmark v1.4.1/go.mod h1:mwnBkeHKe2W/ZEtQ+71ViKU8L12m81fl3OWwC1Zlc8k=

ruleguard/filters.go

@@ -159,6 +159,28 @@ func makeAddressableFilter(src, varname string) filterFunc {
 	}
 }
 
+func makeVarContainsFilter(src, varname string, pat *gogrep.Pattern) filterFunc {
+	// TODO: use a shared state here as well?
+	state := gogrep.NewMatcherState()
+	return func(params *filterParams) matchFilterResult {
+		state.CapturePreset = params.match.CaptureList()
+		matched := false
+		gogrep.Walk(params.subNode(varname), func(n ast.Node) bool {
+			if matched {
+				return false
+			}
+			pat.MatchNode(&state, n, func(m gogrep.MatchData) {
+				matched = true
+			})
+			return true
+		})
+		if matched {
+			return filterSuccess
+		}
+		return filterFailure(src)
+	}
+}
+
 func makeCustomVarFilter(src, varname string, fn *quasigo.Func) filterFunc {
 	return func(params *filterParams) matchFilterResult {
 		// TODO(quasilyte): what if bytecode function panics due to the programming error?

ruleguard/ir/gen_filter_op.go

@@ -62,6 +62,8 @@ func main() {
 		{name: "VarTypeHasMethod", comment: "m[$Value].Type.HasMethod($Args[0])", valueType: "string", flags: flagHasVar},
 		{name: "VarTextMatches", comment: "m[$Value].Text.Matches($Args[0])", valueType: "string", flags: flagHasVar},
 
+		{name: "VarContains", comment: "m[$Value].Contains($Args[0])", valueType: "string", flags: flagHasVar},
+
 		{name: "Deadcode", comment: "m.Deadcode()"},
 
 		{name: "GoVersionEq", comment: "m.GoVersion().Eq($Value)", valueType: "string"},

ruleguard/ir_loader.go

@@ -272,7 +272,8 @@ func (l *irLoader) loadRule(group *ir.RuleGroup, rule *ir.Rule) error {
 	}
 
 	info := filterInfo{
-		Vars: make(map[string]struct{}),
+		Vars:  make(map[string]struct{}),
+		group: group,
 	}
 	if rule.WhereExpr.IsValid() {
 		filter, err := l.newFilter(rule.WhereExpr, &info)
@@ -313,10 +314,7 @@ func (l *irLoader) loadCommentRule(resultProto goRule, rule *ir.Rule, src string
 	return nil
 }
 
-func (l *irLoader) loadSyntaxRule(group *ir.RuleGroup, resultProto goRule, filterInfo filterInfo, rule *ir.Rule, src string, line int) error {
-	result := resultProto
-	result.line = line
-
+func (l *irLoader) gogrepCompile(group *ir.RuleGroup, src string) (*gogrep.Pattern, gogrep.PatternInfo, error) {
 	var imports map[string]string
 	if len(group.Imports) != 0 {
 		imports = make(map[string]string)
@@ -332,7 +330,14 @@ func (l *irLoader) loadSyntaxRule(group *ir.RuleGroup, resultProto goRule, filte
 		WithTypes: true,
 		Imports:   imports,
 	}
-	pat, info, err := gogrep.Compile(gogrepConfig)
+	return gogrep.Compile(gogrepConfig)
+}
+
+func (l *irLoader) loadSyntaxRule(group *ir.RuleGroup, resultProto goRule, filterInfo filterInfo, rule *ir.Rule, src string, line int) error {
+	result := resultProto
+	result.line = line
+
+	pat, info, err := l.gogrepCompile(group, src)
 	if err != nil {
 		return l.errorf(rule.Line, err, "parse match pattern")
 	}
@@ -721,6 +726,14 @@ func (l *irLoader) newFilter(filter ir.FilterExpr, info *filterInfo) (matchFilte
 		}
 		result.fn = makeFileNameMatchesFilter(result.src, re)
 
+	case ir.FilterVarContainsOp:
+		src := filter.Args[0].Value.(string)
+		pat, _, err := l.gogrepCompile(info.group, src)
+		if err != nil {
+			return result, l.errorf(filter.Line, err, "parse contains pattern")
+		}
+		result.fn = makeVarContainsFilter(result.src, filter.Value.(string), pat)
+
 	case ir.FilterVarFilterOp:
 		funcName := filter.Args[0].Value.(string)
 		userFn := l.state.env.GetFunc(l.file.PkgPath, funcName)
@@ -839,4 +852,6 @@ func (l *irLoader) newBinaryExprFilter(filter ir.FilterExpr, info *filterInfo) (
 
 type filterInfo struct {
 	Vars map[string]struct{}
+
+	group *ir.RuleGroup
 }

ruleguard/irconv/irconv.go

@@ -661,6 +661,16 @@ func (conv *converter) convertFilterExprImpl(e ast.Expr) ir.FilterExpr {
 		case "File.Name.Matches":
 			return ir.FilterExpr{Op: ir.FilterFileNameMatchesOp, Value: conv.parseStringArg(e.Args[0])}
 
+		case "Contains":
+			pat := conv.parseStringArg(e.Args[0])
+			return ir.FilterExpr{
+				Op:    ir.FilterVarContainsOp,
+				Value: op.varName,
+				Args: []ir.FilterExpr{
+					{Op: ir.FilterStringOp, Value: pat},
+				},
+			}
+
 		case "Filter":
 			funcName, ok := e.Args[0].(*ast.Ident)
 			if !ok {