add os.getCurrentPkgDir to get closest enclosing nimble pkg dir [back…

…port]

lib/pure/os.nim

@@ -3015,6 +3015,16 @@ proc setLastModificationTime*(file: string, t: times.Time) {.noNimScript.} =
     discard h.closeHandle
     if res == 0'i32: raiseOSError(osLastError())
 
+proc getCurrentPkgDirImpl(dir: string): string =
+  for dir2 in parentDirs(dir, fromRoot = false, inclusive = false):
+    for kind, path in walkDir(dir2, relative = true):
+      if kind == pcFile and path.endsWith ".nimble":
+        when defined(nimscript): return dir2
+        else: return normalizedPath dir2
+
+template getCurrentPkgDir*(dir = instantiationInfo(-1, true).filename): string =
+  ## Returns the path to the closest enclosing nimble package dir
+  getCurrentPkgDirImpl(dir)
 
 when isMainModule:
   assert quoteShellWindows("aaa") == "aaa"

tests/stdlib/nimblepkg/baz/tbaz.nim

@@ -0,0 +1,2 @@
+block getCurrentPkgDir:
+  static: doAssert getCurrentPkgDir() == currentSourcePath.parentDir.parentDir

tests/stdlib/nimblepkg/foo.nimble

@@ -0,0 +1 @@
+# for tbaz.nim

tests/stdlib/tos.nim

@@ -26,6 +26,7 @@ Raises
 # test os path creation, iteration, and deletion
 
 import os, strutils, pathnorm
+import "$nim/compiler/unittest_light"
 
 block fileOperations:
   let files = @["these.txt", "are.x", "testing.r", "files.q"]
@@ -333,3 +334,9 @@ block ospaths:
   doAssert joinPath("", "lib") == "lib"
   doAssert joinPath("", "/lib") == unixToNativePath"/lib"
   doAssert joinPath("usr/", "/lib") == unixToNativePath"usr/lib"
+
+block getCurrentPkgDir:
+  const dir = currentSourcePath.parentDir / "nimblepkg"
+  static:
+    assertEquals getCurrentPkgDir(dir / "baz/tbaz.nim"), dir
+    assertEquals getCurrentPkgDir(dir / "baz"), dir