Fix editable installation from relative paths on Windows

pipenv/project.py

@@ -15,7 +15,7 @@
 from urllib.parse import unquote, urljoin
 
 from pipenv.utils.constants import VCS_LIST
-from pipenv.utils.dependencies import extract_vcs_url
+from pipenv.utils.dependencies import extract_vcs_url, normalize_editable_path_for_pip
 from pipenv.vendor.tomlkit.items import SingleKey, Table
 
 try:
@@ -1187,9 +1187,14 @@ def generate_package_pipfile_entry(
         if extras:
             entry["extras"] = list(extras)
         if path_specifier:
-            entry["file"] = unquote(str(path_specifier))
-            if pip_line.startswith("-e"):
-                entry["editable"] = True
+            editable = pip_line.startswith("-e")
+            entry["file"] = unquote(
+                normalize_editable_path_for_pip(path_specifier)
+                if editable
+                else str(path_specifier)
+            )
+            if editable:
+                entry["editable"] = editable
         elif vcs_specifier:
             for vcs in VCS_LIST:
                 if vcs in package.link.scheme:

pipenv/routines/install.py

@@ -13,6 +13,7 @@
     expansive_install_req_from_line,
     get_lockfile_section_using_pipfile_category,
     install_req_from_pipfile,
+    normalize_editable_path_for_pip,
 )
 from pipenv.utils.indexes import get_source_list
 from pipenv.utils.internet import download_file, is_valid_url
@@ -44,7 +45,9 @@ def handle_new_packages(
     new_packages = []
     if packages or editable_packages:
 
-        pkg_list = packages + [f"-e {pkg}" for pkg in editable_packages]
+        pkg_list = packages + [
+            f"-e {normalize_editable_path_for_pip(pkg)}" for pkg in editable_packages
+        ]
 
         for pkg_line in pkg_list:
             console.print(f"Installing {pkg_line}...", style="bold green")
@@ -262,7 +265,11 @@ def do_install(
     )
     warnings.filterwarnings("ignore", category=ResourceWarning)
     packages = packages if packages else []
-    editable_packages = editable_packages if editable_packages else []
+    editable_packages = (
+        [normalize_editable_path_for_pip(p) for p in editable_packages]
+        if editable_packages
+        else []
+    )
     package_args = [p for p in packages if p] + [p for p in editable_packages if p]
     new_packages = []
     if dev and not pipfile_categories:

pipenv/utils/dependencies.py

@@ -1068,6 +1068,13 @@ def expansive_install_req_from_line(
     return install_req, name
 
 
+def normalize_editable_path_for_pip(path_str):
+    """Normalize an editable package path for pip."""
+    # Windows paths need to be converted to POSIX paths otherwise path
+    # separators (back slashes) are interpreted as escape characters.
+    return path_str.replace(os.path.sep, "/")
+
+
 def file_path_from_pipfile(path_str, pipfile_entry):
     """Creates an installable file path from a pipfile entry.
     Handles local and remote paths, files and directories;
@@ -1082,7 +1089,7 @@ def file_path_from_pipfile(path_str, pipfile_entry):
     if pipfile_entry.get("extras"):
         req_str = f"{req_str}[{','.join(pipfile_entry['extras'])}]"
     if pipfile_entry.get("editable", False):
-        req_str = f"-e {req_str}"
+        req_str = f"-e {normalize_editable_path_for_pip(req_str)}"
 
     return req_str