Revert "cmd/go/internal/modload: record the replacement for the module containing package main in BuildInfo"

This reverts CL 220645 (commit e092fc352ad393a4d2f1f7fa641df2d23572ccff).

Reason for revert: Seems to have broken windows/amd64 longtest

Change-Id: Iffa8c882524250e5845514bc827fcd8927645a44
Reviewed-on: https://go-review.googlesource.com/c/go/+/220722
Run-TryBot: Andrew Bonventre <andybons@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

1 files changed, 21 insertions, 30 deletions

diff --git a/src/runtime/debug/mod.go b/src/runtime/debug/mod.go
index 0381bdcc53..837cd689a0 100644
--- a/src/runtime/debug/mod.go
+++ b/src/runtime/debug/mod.go
@@ -47,27 +47,9 @@ func readBuildInfo(data string) (*BuildInfo, bool) {
 		repLine  = "=>\t"
 	)
 
-	readEntryFirstLine := func(elem []string) (Module, bool) {
-		if len(elem) != 2 && len(elem) != 3 {
-			return Module{}, false
-		}
-		sum := ""
-		if len(elem) == 3 {
-			sum = elem[2]
-		}
-		return Module{
-			Path:    elem[0],
-			Version: elem[1],
-			Sum:     sum,
-		}, true
-	}
+	info := &BuildInfo{}
 
-	var (
-		info = &BuildInfo{}
-		last *Module
-		line string
-		ok   bool
-	)
+	var line string
 	// Reverse of cmd/go/internal/modload.PackageBuildInfo
 	for len(data) > 0 {
 		i := strings.IndexByte(data, '\n')
@@ -81,33 +63,42 @@ func readBuildInfo(data string) (*BuildInfo, bool) {
 			info.Path = elem
 		case strings.HasPrefix(line, modLine):
 			elem := strings.Split(line[len(modLine):], "\t")
-			last = &info.Main
-			*last, ok = readEntryFirstLine(elem)
-			if !ok {
+			if len(elem) != 3 {
 				return nil, false
 			}
+			info.Main = Module{
+				Path:    elem[0],
+				Version: elem[1],
+				Sum:     elem[2],
+			}
 		case strings.HasPrefix(line, depLine):
 			elem := strings.Split(line[len(depLine):], "\t")
-			last = new(Module)
-			info.Deps = append(info.Deps, last)
-			*last, ok = readEntryFirstLine(elem)
-			if !ok {
+			if len(elem) != 2 && len(elem) != 3 {
 				return nil, false
 			}
+			sum := ""
+			if len(elem) == 3 {
+				sum = elem[2]
+			}
+			info.Deps = append(info.Deps, &Module{
+				Path:    elem[0],
+				Version: elem[1],
+				Sum:     sum,
+			})
 		case strings.HasPrefix(line, repLine):
 			elem := strings.Split(line[len(repLine):], "\t")
 			if len(elem) != 3 {
 				return nil, false
 			}
-			if last == nil {
+			last := len(info.Deps) - 1
+			if last < 0 {
 				return nil, false
 			}
-			last.Replace = &Module{
+			info.Deps[last].Replace = &Module{
 				Path:    elem[0],
 				Version: elem[1],
 				Sum:     elem[2],
 			}
-			last = nil
 		}
 	}
 	return info, true