From ae42498940e6673cb87927cc8ccbe26e0e8c45ce Mon Sep 17 00:00:00 2001
From: "Iskander (Alex) Sharipov" <quasilyte@gmail.com>
Date: Sat, 1 Oct 2022 16:27:37 +0400
Subject: [PATCH] ruleguard/typematch: replace Split with Index to avoid allocs
 (#414)

We don't need to create `[]string` to compare the substring.
This change reduces the amount of allocations when comparing
named types via typematch package.
---
 ruleguard/typematch/typematch.go | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/ruleguard/typematch/typematch.go b/ruleguard/typematch/typematch.go
index b747403..4b740b2 100644
--- a/ruleguard/typematch/typematch.go
+++ b/ruleguard/typematch/typematch.go
@@ -507,9 +507,14 @@ func (p *Pattern) matchIdentical(state *MatcherState, sub *pattern, typ types.Ty
 		}
 		pkgPath := sub.value.([2]string)[0]
 		typeName := sub.value.([2]string)[1]
-		// obj.Pkg().Path() may be in a vendor directory.
-		path := strings.SplitAfter(obj.Pkg().Path(), "/vendor/")
-		return path[len(path)-1] == pkgPath && typeName == obj.Name()
+		if typeName != obj.Name() {
+			return false
+		}
+		objPath := obj.Pkg().Path()
+		if vendorPos := strings.Index(objPath, "/vendor/"); vendorPos != -1 {
+			objPath = objPath[vendorPos+len("/vendor/"):]
+		}
+		return objPath == pkgPath
 
 	case opFuncNoSeq:
 		typ, ok := typ.(*types.Signature)