cmd/go: check case-insensitive path collisions for go mod vendor.

Fixes: #38571
Change-Id: Iec1cd1532ff17f7d943149f9b6a79e7fd419d179
Cq-Include-Trybots: luci.golang.try:gotip-linux-amd64-longtest,gotip-windows-amd64-longtest
Reviewed-on: https://go-review.googlesource.com/c/go/+/570775
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Bryan Mills <bcmills@google.com>

diff --git a/src/cmd/go/internal/load/pkg.go b/src/cmd/go/internal/load/pkg.go
index 0e4b6797c6ecdb608847335f487ae8af931857e5..4b40cc9ddbe5e89d3c5eab17bd095ea707b5bd31 100644 (file)
--- a/src/cmd/go/internal/load/pkg.go
+++ b/src/cmd/go/internal/load/pkg.go
@@ -1937,6 +1937,8 @@ func (p *Package) load(ctx context.Context, opts PackageOpts, path string, stk *
        }
 
        // Check for case-insensitive collisions of import paths.
+       // If modifying, consider changing checkPathCollisions() in
+       // src/cmd/go/internal/modcmd/vendor.go
        fold := str.ToFold(p.ImportPath)
        if other := foldPath[fold]; other == "" {
                foldPath[fold] = p.ImportPath

diff --git a/src/cmd/go/internal/modcmd/vendor.go b/src/cmd/go/internal/modcmd/vendor.go
index 44e0439f6876d449cf7988a2f5db213b25c1449d..5b0b9bbea6fdbbb46885034963752a804d1ea0ef 100644 (file)
--- a/src/cmd/go/internal/modcmd/vendor.go
+++ b/src/cmd/go/internal/modcmd/vendor.go
@@ -111,6 +111,7 @@ func RunVendor(ctx context.Context, vendorE bool, vendorO string, args []string)
                }
                modpkgs[m] = append(modpkgs[m], pkg)
        }
+       checkPathCollisions(modpkgs)
 
        includeAllReplacements := false
        includeGoVersions := false
@@ -492,3 +493,19 @@ func copyDir(dst, src string, match func(dir string, info fs.DirEntry) bool, cop
                }
        }
 }
+
+// checkPathCollisions will fail if case-insensitive collisions are present.
+// The reason why we do this check in go mod vendor is to keep consistentcy
+// with go build. If modifying, consider changing load() in
+// src/cmd/go/internal/load/pkg.go
+func checkPathCollisions(modpkgs map[module.Version][]string) {
+       var foldPath = make(map[string]string, len(modpkgs))
+       for m := range modpkgs {
+               fold := str.ToFold(m.Path)
+               if other := foldPath[fold]; other == "" {
+                       foldPath[fold] = m.Path
+               } else if other != m.Path {
+                       base.Fatalf("go.mod: case-insensitive import collision: %q and %q", m.Path, other)
+               }
+       }
+}

diff --git a/src/cmd/go/testdata/script/mod_vendor_collision.txt b/src/cmd/go/testdata/script/mod_vendor_collision.txt
new file mode 100644 (file)
index 0000000..e15b7ed
--- /dev/null
+++ b/src/cmd/go/testdata/script/mod_vendor_collision.txt
@@ -0,0 +1,38 @@
+! go build
+stderr 'case-insensitive import collision'
+
+! go mod vendor
+stderr 'case-insensitive import collision'
+
+-- foo.go --
+package main
+
+import (
+       _ "example.com/Foo"
+       _ "example.com/foo"
+)
+
+func main() {}
+-- go.mod --
+module play.ground
+
+go 1.14
+
+require (
+       example.com/foo v0.1.0
+       example.com/Foo v0.1.0
+)
+
+replace (
+       example.com/foo => ./foo
+       example.com/Foo => ./foo_alt
+)
+-- foo/go.mod --
+module example.com/foo
+-- foo/foo.go --
+package foo
+
+-- foo_alt/go.mod --
+module example.com/Foo
+-- foo_alt/foo.go --
+package Foo
\ No newline at end of file