From 2216387fa7545ed89d58107fe0a2d996864c69c3 Mon Sep 17 00:00:00 2001
From: Denis Isaev <denis@golangci.com>
Date: Sun, 20 Jan 2019 21:56:57 +0300
Subject: [PATCH] speedup typecheck on large project with compilation errors

---
 pkg/packages/util.go | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/pkg/packages/util.go b/pkg/packages/util.go
index 804c2a19..6d368ac6 100644
--- a/pkg/packages/util.go
+++ b/pkg/packages/util.go
@@ -10,7 +10,7 @@ import (
 
 //nolint:gocyclo
 func ExtractErrors(pkg *packages.Package, astCache *astcache.Cache) []packages.Error {
-	errors := extractErrorsImpl(pkg)
+	errors := extractErrorsImpl(pkg, map[*packages.Package]bool{})
 	if len(errors) == 0 {
 		return errors
 	}
@@ -48,7 +48,12 @@ func ExtractErrors(pkg *packages.Package, astCache *astcache.Cache) []packages.E
 	return uniqErrors
 }
 
-func extractErrorsImpl(pkg *packages.Package) []packages.Error {
+func extractErrorsImpl(pkg *packages.Package, seenPackages map[*packages.Package]bool) []packages.Error {
+	if seenPackages[pkg] {
+		return nil
+	}
+	seenPackages[pkg] = true
+
 	if !pkg.IllTyped { // otherwise it may take hours to traverse all deps many times
 		return nil
 	}
@@ -59,7 +64,7 @@ func extractErrorsImpl(pkg *packages.Package) []packages.Error {
 
 	var errors []packages.Error
 	for _, iPkg := range pkg.Imports {
-		iPkgErrors := extractErrorsImpl(iPkg)
+		iPkgErrors := extractErrorsImpl(iPkg, seenPackages)
 		if iPkgErrors != nil {
 			errors = append(errors, iPkgErrors...)
 		}