diff --git a/analyzer/analyzer.go b/analyzer/analyzer.go
index 2bd5ba21..4dd0f8a0 100644
--- a/analyzer/analyzer.go
+++ b/analyzer/analyzer.go
@@ -3,7 +3,6 @@ package analyzer
 import (
 	"bytes"
 	"fmt"
-	"go/ast"
 	"go/token"
 	"io/ioutil"
 	"os"
@@ -105,17 +104,19 @@ func runAnalyzer(pass *analysis.Pass) (interface{}, error) {
 		Sizes:        pass.TypesSizes,
 		Fset:         pass.Fset,
 		GoVersion:    goVersion,
-		Report: func(info ruleguard.GoRuleInfo, n ast.Node, msg string, s *ruleguard.Suggestion) {
-			fullMessage := msg
+		Report: func(data *ruleguard.ReportData) {
+			fullMessage := data.Message
+			info := data.RuleInfo
 			if printRuleLocation {
 				fullMessage = fmt.Sprintf("%s: %s (%s:%d)",
-					info.Group.Name, msg, filepath.Base(info.Group.Filename), info.Line)
+					info.Group.Name, data.Message, filepath.Base(info.Group.Filename), info.Line)
 			}
 			diag := analysis.Diagnostic{
-				Pos:     n.Pos(),
+				Pos:     data.Node.Pos(),
 				Message: fullMessage,
 			}
-			if s != nil {
+			if data.Suggestion != nil {
+				s := data.Suggestion
 				diag.SuggestedFixes = []analysis.SuggestedFix{
 					{
 						Message: "suggested replacement",
diff --git a/analyzer/testanalyzer/testanalyzer.go b/analyzer/testanalyzer/testanalyzer.go
index 32380184..8052bc08 100644
--- a/analyzer/testanalyzer/testanalyzer.go
+++ b/analyzer/testanalyzer/testanalyzer.go
@@ -2,7 +2,6 @@ package testanalyzer
 
 import (
 	"fmt"
-	"go/ast"
 	"go/token"
 	"path/filepath"
 
@@ -26,11 +25,13 @@ func New(ruleSet *ir.File) *analysis.Analyzer {
 			Types: pass.TypesInfo,
 			Sizes: pass.TypesSizes,
 			Fset:  pass.Fset,
-			Report: func(info ruleguard.GoRuleInfo, n ast.Node, msg string, s *ruleguard.Suggestion) {
+			Report: func(data *ruleguard.ReportData) {
+				info := data.RuleInfo
+				msg := data.Message
 				fullMessage := fmt.Sprintf("%s: %s (%s:%d)",
 					info.Group.Name, msg, filepath.Base(info.Group.Filename), info.Line)
 				pass.Report(analysis.Diagnostic{
-					Pos:     n.Pos(),
+					Pos:     data.Node.Pos(),
 					Message: fullMessage,
 				})
 			},
diff --git a/ruleguard/ast_walker.go b/ruleguard/ast_walker.go
index e3d7ea70..c16f9436 100644
--- a/ruleguard/ast_walker.go
+++ b/ruleguard/ast_walker.go
@@ -306,6 +306,7 @@ func (w *astWalker) walk(n ast.Node) {
 		if n.Doc != nil {
 			w.walk(n.Doc)
 		}
+		prevFunc := w.filterParams.currentFunc
 		if n.Recv != nil {
 			w.walk(n.Recv)
 		}
@@ -314,6 +315,7 @@ func (w *astWalker) walk(n ast.Node) {
 		if n.Body != nil {
 			w.walk(n.Body)
 		}
+		w.filterParams.currentFunc = prevFunc
 
 	case *ast.File:
 		w.walk(n.Name)
diff --git a/ruleguard/debug_test.go b/ruleguard/debug_test.go
index 32e2de24..805eceaf 100644
--- a/ruleguard/debug_test.go
+++ b/ruleguard/debug_test.go
@@ -254,7 +254,7 @@ func newDebugTestRunner(input string) (*debugTestRunner, error) {
 		Types: &info,
 		Sizes: types.SizesFor("gc", runtime.GOARCH),
 		Fset:  fset,
-		Report: func(info GoRuleInfo, n ast.Node, msg string, s *Suggestion) {
+		Report: func(data *ReportData) {
 			// Do nothing.
 		},
 	}
diff --git a/ruleguard/gorule.go b/ruleguard/gorule.go
index 90963f43..7c213b44 100644
--- a/ruleguard/gorule.go
+++ b/ruleguard/gorule.go
@@ -67,6 +67,8 @@ type filterParams struct {
 
 	deadcode bool
 
+	currentFunc *ast.FuncDecl
+
 	// varname is set only for custom filters before bytecode function is called.
 	varname string
 }
diff --git a/ruleguard/perf_test.go b/ruleguard/perf_test.go
index c700f5a0..283c3017 100644
--- a/ruleguard/perf_test.go
+++ b/ruleguard/perf_test.go
@@ -49,7 +49,7 @@ func benchRunContext(b *testing.B, src string) (*RunContext, *ast.File) {
 		Types: typesInfo,
 		Sizes: types.SizesFor("gc", runtime.GOARCH),
 		Fset:  fset,
-		Report: func(info GoRuleInfo, n ast.Node, msg string, s *Suggestion) {
+		Report: func(data *ReportData) {
 			// Do nothing.
 		},
 	}
diff --git a/ruleguard/ruleguard.go b/ruleguard/ruleguard.go
index 7e0f40f3..2642bb7b 100644
--- a/ruleguard/ruleguard.go
+++ b/ruleguard/ruleguard.go
@@ -93,15 +93,31 @@ type RunContext struct {
 	DebugImports bool
 	DebugPrint   func(string)
 
-	Types  *types.Info
-	Sizes  types.Sizes
-	Fset   *token.FileSet
-	Report func(rule GoRuleInfo, n ast.Node, msg string, s *Suggestion)
-	Pkg    *types.Package
+	Types *types.Info
+	Sizes types.Sizes
+	Fset  *token.FileSet
+	Pkg   *types.Package
+
+	// Report is a function that is called for every successful ruleguard match.
+	// The pointer to ReportData is reused, it should not be kept.
+	// If you want to keep it after Report() returns, make a copy.
+	Report func(*ReportData)
 
 	GoVersion GoVersion
 }
 
+type ReportData struct {
+	RuleInfo   GoRuleInfo
+	Node       ast.Node
+	Message    string
+	Suggestion *Suggestion
+
+	// Experimental: fields below are part of the experiment.
+	// They'll probably be removed or changed over time.
+
+	Func *ast.FuncDecl
+}
+
 type Suggestion struct {
 	From        token.Pos
 	To          token.Pos
diff --git a/ruleguard/runner.go b/ruleguard/runner.go
index 4f1aabdf..8b7824db 100644
--- a/ruleguard/runner.go
+++ b/ruleguard/runner.go
@@ -23,6 +23,8 @@ type rulesRunner struct {
 	ctx   *RunContext
 	rules *goRuleSet
 
+	reportData ReportData
+
 	gogrepState gogrep.MatcherState
 
 	importer *goImporter
@@ -291,7 +293,12 @@ func (rr *rulesRunner) handleCommentMatch(rule goCommentRule, m commentMatchData
 		Group: rule.base.group,
 		Line:  rule.base.line,
 	}
-	rr.ctx.Report(info, node, message, suggestion)
+	rr.reportData.RuleInfo = info
+	rr.reportData.Node = node
+	rr.reportData.Message = message
+	rr.reportData.Suggestion = suggestion
+
+	rr.ctx.Report(&rr.reportData)
 	return true
 }
 
@@ -322,7 +329,14 @@ func (rr *rulesRunner) handleMatch(rule goRule, m gogrep.MatchData) bool {
 		Group: rule.group,
 		Line:  rule.line,
 	}
-	rr.ctx.Report(info, node, message, suggestion)
+	rr.reportData.RuleInfo = info
+	rr.reportData.Node = node
+	rr.reportData.Message = message
+	rr.reportData.Suggestion = suggestion
+
+	rr.reportData.Func = rr.filterParams.currentFunc
+
+	rr.ctx.Report(&rr.reportData)
 	return true
 }