Resolve dependencies when imports are relative to the package path

Author: yushan8

gazelle/python/file_parser.go

@@ -165,7 +165,9 @@ func (p *FileParser) parseImportStatements(node *sitter.Node) bool {
 		}
 	} else if node.Type() == sitterNodeTypeImportFromStatement {
 		from := node.Child(1).Content(p.code)
-		if strings.HasPrefix(from, ".") {
+		// If the import is from the current package, we don't need to add it to the modules i.e. from . import Class1.
+		// If the import is from a different relative package i.e. from .package1 import foo, we need to add it to the modules.
+		if from == "." {
 			return true
 		}
 		for j := 3; j < int(node.ChildCount()); j++ {

gazelle/python/resolve.go

@@ -148,12 +148,56 @@ func (py *Resolver) Resolve(
 		modules := modulesRaw.(*treeset.Set)
 		it := modules.Iterator()
 		explainDependency := os.Getenv("EXPLAIN_DEPENDENCY")
+		// Resolve relative paths for package generation
+		isPackageGeneration := !cfg.PerFileGeneration() && !cfg.CoarseGrainedGeneration()
 		hasFatalError := false
 	MODULES_LOOP:
 		for it.Next() {
 			mod := it.Value().(module)
-			moduleParts := strings.Split(mod.Name, ".")
-			possibleModules := []string{mod.Name}
+			moduleName := mod.Name
+			// Transform relative imports `.` or `..foo.bar` into the package path from root.
+			if strings.HasPrefix(moduleName, ".") {
+				// If not package generation mode, skip relative imports
+				if !isPackageGeneration {
+					continue MODULES_LOOP
+				}
+				relativeDepth := 0
+				for i := 0; i < len(moduleName); i++ {
+					if moduleName[i] == '.' {
+						relativeDepth++
+					} else {
+						break
+					}
+				}
+
+				// Extract suffix after leading dots
+				relativeSuffix := moduleName[relativeDepth:]
+				var relativeSuffixParts []string
+				if relativeSuffix != "" {
+					relativeSuffixParts = strings.Split(relativeSuffix, ".")
+				}
+
+				// Split current package label into parts
+				pkgParts := strings.Split(from.Pkg, "/")
+
+				if relativeDepth- 1 > len(pkgParts) {
+					// Trying to go above the root
+					log.Printf("ERROR: Invalid relative import %q in %q: exceeds package root.", moduleName, mod.Filepath)
+					continue MODULES_LOOP
+				}
+
+				// Go up `relativeDepth - 1` levels
+				baseParts := pkgParts
+				if relativeDepth > 1 {
+					baseParts = pkgParts[:len(pkgParts)-(relativeDepth-1)]
+				}
+
+				absParts := append(baseParts, relativeSuffixParts...)
+				moduleName = strings.Join(absParts, ".")
+			}
+
+			moduleParts := strings.Split(moduleName, ".")
+			possibleModules := []string{moduleName}
 			for len(moduleParts) > 1 {
 				// Iterate back through the possible imports until
 				// a match is found.

gazelle/python/testdata/relative_imports/README.md

@@ -0,0 +1 @@
+# gazelle:python_generation_mode package

gazelle/python/testdata/relative_imports_package_mode/BUILD.in

@@ -0,0 +1,14 @@
+load("@rules_python//python:defs.bzl", "py_binary")
+
+# gazelle:python_generation_mode package
+
+py_binary(
+    name = "relative_imports_package_mode_bin",
+    srcs = ["__main__.py"],
+    main = "__main__.py",
+    visibility = ["//:__subpackages__"],
+    deps = [
+        "//package1",
+        "//package2",
+    ],
+)

gazelle/python/testdata/relative_imports_package_mode/BUILD.out

@@ -0,0 +1,3 @@
+# Resolve deps for relative imports
+
+This test case verifies that the generated targets correctly handle relative imports in Python. Specifically, when the Python generation mode is set to "package," it ensures that relative import statements such as from .foo import X are properly resolved to their corresponding modules.

gazelle/python/testdata/relative_imports_package_mode/README.md

@@ -0,0 +1,5 @@
+from package1.module1 import function1
+from package2.module3 import function3
+
+print(function1())
+print(function3())

gazelle/python/testdata/relative_imports/WORKSPACE renamed to gazelle/python/testdata/relative_imports_package_mode/WORKSPACE

@@ -0,0 +1,10 @@
+load("@rules_python//python:defs.bzl", "py_library")
+
+py_library(
+    name = "package1",
+    srcs = [
+        "module1.py",
+        "module2.py",
+    ],
+    visibility = ["//:__subpackages__"],
+)