mod: add local module replacement support with robust path resolution

cmd/cue/cmd/modtidy.go

@@ -25,6 +25,7 @@ import (
 
 	"cuelang.org/go/internal/mod/modload"
 	"cuelang.org/go/mod/modfile"
+	"cuelang.org/go/mod/module"
 )
 
 func newModTidyCmd(c *Command) *cobra.Command {
@@ -62,10 +63,10 @@ func runModTidy(cmd *Command, args []string) error {
 		return err
 	}
 	if flagCheck.Bool(cmd) {
-		err := modload.CheckTidy(ctx, os.DirFS(modRoot), ".", reg)
+		err := modload.CheckTidy(ctx, module.OSDirFS(modRoot), ".", reg)
 		return suggestModCommand(err)
 	}
-	mf, err := modload.Tidy(ctx, os.DirFS(modRoot), ".", reg)
+	mf, err := modload.Tidy(ctx, module.OSDirFS(modRoot), ".", reg)
 	if err != nil {
 		return suggestModCommand(err)
 	}

cmd/cue/cmd/testdata/script/modreplace_local.txtar

@@ -0,0 +1,53 @@
+# Test local path replace directives
+
+# The main module references a dependency that is replaced with a local path.
+# The local-dep directory contains the replacement module.
+
+# Test that cue mod tidy works with local replacements
+exec cue mod tidy
+cmp cue.mod/module.cue want-module.cue
+
+# Test that cue eval uses the local replacement
+exec cue eval .
+cmp stdout want-eval.txt
+
+# Test that cue export also works
+exec cue export .
+stdout '"from local replacement"'
+
+-- cue.mod/module.cue --
+module: "example.com/main@v0"
+language: version: "v0.9.0"
+
+deps: {
+    "example.com/dep@v0": {
+        v: "v0.1.0"
+        replace: "./local-dep"
+    }
+}
+-- main.cue --
+package main
+
+import "example.com/dep@v0:lib"
+
+output: lib.value
+-- local-dep/cue.mod/module.cue --
+module: "example.com/dep@v0"
+language: version: "v0.9.0"
+-- local-dep/lib.cue --
+package lib
+
+value: "from local replacement"
+-- want-eval.txt --
+output: "from local replacement"
+-- want-module.cue --
+module: "example.com/main@v0"
+language: {
+	version: "v0.9.0"
+}
+deps: {
+	"example.com/dep@v0": {
+		v:       "v0.1.0"
+		replace: "./local-dep"
+	}
+}

cmd/cue/cmd/testdata/script/modreplace_local_commands.txtar

@@ -0,0 +1,43 @@
+# Test that various cue commands work with local replacements
+
+# Test cue mod tidy
+exec cue mod tidy
+
+# Test cue eval
+exec cue eval .
+stdout 'output: "from local"'
+
+# Test cue export
+exec cue export .
+stdout '"from local"'
+
+# Test cue vet (should pass validation)
+exec cue vet .
+
+# Test cue def (show definitions)
+exec cue def .
+stdout 'output:'
+
+-- cue.mod/module.cue --
+module: "example.com/main@v0"
+language: version: "v0.9.0"
+
+deps: {
+    "example.com/dep@v0": {
+        v: "v0.1.0"
+        replace: "./local-dep"
+    }
+}
+-- main.cue --
+package main
+
+import "example.com/dep@v0:lib"
+
+output: lib.value
+-- local-dep/cue.mod/module.cue --
+module: "example.com/dep@v0"
+language: version: "v0.9.0"
+-- local-dep/lib.cue --
+package lib
+
+value: "from local"

cmd/cue/cmd/testdata/script/modreplace_local_missing.txtar

@@ -0,0 +1,22 @@
+# Test error handling when local replacement directory does not exist
+
+# cue mod tidy should fail when the replacement directory is missing
+! exec cue mod tidy
+stderr 'does not exist'
+
+-- cue.mod/module.cue --
+module: "example.com/main@v0"
+language: version: "v0.9.0"
+
+deps: {
+    "example.com/missing@v0": {
+        v: "v0.1.0"
+        replace: "./nonexistent-dir"
+    }
+}
+-- main.cue --
+package main
+
+import "example.com/missing@v0:lib"
+
+output: lib.value

cmd/cue/cmd/testdata/script/modreplace_local_nested.txtar

@@ -0,0 +1,47 @@
+# Test local path replace directives with nested dependencies
+# The local-dep module has its own dependencies that must be resolved.
+
+# Test that cue mod tidy works with local replacements that have dependencies
+exec cue mod tidy
+cmp cue.mod/module.cue want-module.cue
+
+# Test that cue eval uses the local replacement and its dependencies
+exec cue eval .
+cmp stdout want-eval.txt
+
+-- cue.mod/module.cue --
+module: "example.com/main@v0"
+language: version: "v0.9.0"
+
+deps: {
+    "example.com/dep@v0": {
+        v: "v0.1.0"
+        replace: "./local-dep"
+    }
+}
+-- main.cue --
+package main
+
+import "example.com/dep@v0:lib"
+
+output: lib.value
+-- local-dep/cue.mod/module.cue --
+module: "example.com/dep@v0"
+language: version: "v0.9.0"
+-- local-dep/lib.cue --
+package lib
+
+value: "from local with deps"
+-- want-eval.txt --
+output: "from local with deps"
+-- want-module.cue --
+module: "example.com/main@v0"
+language: {
+	version: "v0.9.0"
+}
+deps: {
+	"example.com/dep@v0": {
+		v:       "v0.1.0"
+		replace: "./local-dep"
+	}
+}

cmd/cue/cmd/testdata/script/modreplace_local_sibling.txtar

@@ -0,0 +1,55 @@
+# Test local path replace directives with sibling directory (../)
+
+# Create the sibling directory structure
+mkdir sibling-dep
+mkdir sibling-dep/cue.mod
+cp sibling-module.cue sibling-dep/cue.mod/module.cue
+cp sibling-lib.cue sibling-dep/lib.cue
+
+# Run from the main directory
+cd main
+
+# Test that cue mod tidy works with sibling path replacements
+exec cue mod tidy
+cmp cue.mod/module.cue want-module.cue
+
+# Test that cue eval uses the sibling replacement
+exec cue eval .
+cmp stdout want-eval.txt
+
+-- sibling-module.cue --
+module: "example.com/sibling@v0"
+language: version: "v0.9.0"
+-- sibling-lib.cue --
+package lib
+
+value: "from sibling directory"
+-- main/cue.mod/module.cue --
+module: "example.com/main@v0"
+language: version: "v0.9.0"
+
+deps: {
+    "example.com/sibling@v0": {
+        v: "v0.1.0"
+        replace: "../sibling-dep"
+    }
+}
+-- main/main.cue --
+package main
+
+import "example.com/sibling@v0:lib"
+
+output: lib.value
+-- main/want-eval.txt --
+output: "from sibling directory"
+-- main/want-module.cue --
+module: "example.com/main@v0"
+language: {
+	version: "v0.9.0"
+}
+deps: {
+	"example.com/sibling@v0": {
+		v:       "v0.1.0"
+		replace: "../sibling-dep"
+	}
+}

cmd/cue/cmd/testdata/script/modreplace_preserve_orphan.txtar

@@ -0,0 +1,71 @@
+# Test that replace directives are preserved when dependency is removed
+#
+# This tests that replace directives are intentionally preserved during tidy
+# even when the dependency is no longer used (matching Go's go mod tidy behavior).
+# This allows users to maintain replacements for dependencies that may be
+# re-added later without losing the configuration.
+
+# Initial state: main.cue imports dep, module.cue has replace directive
+exec cue mod tidy
+exec cue eval .
+stdout '"from local replacement"'
+
+# Remove the import from main.cue
+cp _templates/main_no_import.cue main.cue
+
+# Run tidy - the replace directive should be preserved even though dep is unused
+exec cue mod tidy
+cmp cue.mod/module.cue _golden/want-module-after-tidy.cue
+
+# Re-add the import
+cp _templates/main_with_import.cue main.cue
+
+# Verify the replacement still works after tidy
+exec cue mod tidy
+exec cue eval .
+stdout '"from local replacement"'
+
+-- cue.mod/module.cue --
+module: "example.com/main@v0"
+language: version: "v0.9.0"
+
+deps: {
+    "example.com/dep@v0": {
+        v: "v0.1.0"
+        replace: "./local-dep"
+    }
+}
+-- main.cue --
+package main
+
+import "example.com/dep@v0:lib"
+
+output: lib.value
+-- _templates/main_with_import.cue --
+package main
+
+import "example.com/dep@v0:lib"
+
+output: lib.value
+-- _templates/main_no_import.cue --
+package main
+
+output: "no dependency"
+-- local-dep/cue.mod/module.cue --
+module: "example.com/dep@v0"
+language: version: "v0.9.0"
+-- local-dep/lib.cue --
+package lib
+
+value: "from local replacement"
+-- _golden/want-module-after-tidy.cue --
+module: "example.com/main@v0"
+language: {
+	version: "v0.9.0"
+}
+deps: {
+	"example.com/dep@v0": {
+		v:       "v0.1.0"
+		replace: "./local-dep"
+	}
+}

cmd/cue/cmd/testdata/script/modreplace_remote.txtar

@@ -0,0 +1,54 @@
+# Test remote module replace directives
+# A module can be replaced with a different module from the registry.
+
+# Test that cue mod tidy works with remote replacements
+exec cue mod tidy
+cmp cue.mod/module.cue want-module.cue
+
+# Test that cue eval uses the replacement module
+exec cue eval .
+cmp stdout want-eval.txt
+
+-- cue.mod/module.cue --
+module: "example.com/main@v0"
+language: version: "v0.9.0"
+
+deps: {
+    "example.com/original@v0": {
+        v: "v0.1.0"
+        replace: "example.com/[email protected]"
+    }
+}
+-- main.cue --
+package main
+
+import "example.com/original@v0:lib"
+
+output: lib.value
+-- _registry/example.com_original_v0.1.0/cue.mod/module.cue --
+module: "example.com/original@v0"
+language: version: "v0.9.0"
+-- _registry/example.com_original_v0.1.0/lib.cue --
+package lib
+
+value: "from original (should not see this)"
+-- _registry/example.com_replacement_v0.1.0/cue.mod/module.cue --
+module: "example.com/replacement@v0"
+language: version: "v0.9.0"
+-- _registry/example.com_replacement_v0.1.0/lib.cue --
+package lib
+
+value: "from replacement module"
+-- want-eval.txt --
+output: "from replacement module"
+-- want-module.cue --
+module: "example.com/main@v0"
+language: {
+	version: "v0.9.0"
+}
+deps: {
+	"example.com/original@v0": {
+		v:       "v0.1.0"
+		replace: "example.com/[email protected]"
+	}
+}