fix #18735; genDepend broken for duplicate module names in separate folders (#19988)

(cherry picked from commit 0180c6179a)

compiler/depends.nim

@@ -9,10 +9,12 @@
 
 # This module implements a dependency file generator.
 
-import
-  options, ast, ropes, idents, passes, modulepaths, pathutils
+import options, ast, ropes, passes, pathutils, msgs, lineinfos
 
-from modulegraphs import ModuleGraph, PPassContext
+import modulegraphs
+
+import std/[os, strutils, parseutils]
+import std/private/globs
 
 type
   TGen = object of PPassContext
@@ -28,6 +30,50 @@ proc addDependencyAux(b: Backend; importing, imported: string) =
   b.dotGraph.addf("\"$1\" -> \"$2\";$n", [rope(importing), rope(imported)])
   # s1 -> s2_4[label="[0-9]"];
 
+proc toNimblePath(s: string, isStdlib: bool): string =
+  const stdPrefix = "std/"
+  const pkgPrefix = "pkg/"
+  if isStdlib:
+    let sub = "lib/"
+    var start = s.find(sub)
+    if start < 0:
+      doAssert false
+    else:
+      start += sub.len
+      let base = s[start..^1]
+
+      if base.startsWith("system") or base.startsWith("std"):
+        result = base
+      else:
+        for dir in stdlibDirs:
+          if base.startsWith(dir):
+            return stdPrefix & base.splitFile.name
+
+        result = stdPrefix & base
+  else:
+    var sub = getEnv("NIMBLE_DIR")
+    if sub.len == 0:
+      sub = ".nimble/pkgs/"
+    else:
+      sub.add "/pkgs/"
+    var start = s.find(sub)
+    if start < 0:
+      result = s
+    else:
+      start += sub.len
+      start += skipUntil(s, '/', start)
+      start += 1
+      result = pkgPrefix & s[start..^1]
+
+proc addDependency(c: PPassContext, g: PGen, b: Backend, n: PNode) =
+  doAssert n.kind == nkSym, $n.kind
+
+  let path = splitFile(toProjPath(g.config, n.sym.position.FileIndex))
+  let modulePath = splitFile(toProjPath(g.config, g.module.position.FileIndex))
+  let parent = nativeToUnixPath(modulePath.dir / modulePath.name).toNimblePath(belongsToStdlib(g.graph, g.module))
+  let child = nativeToUnixPath(path.dir / path.name).toNimblePath(belongsToStdlib(g.graph, n.sym))
+  addDependencyAux(b, parent, child)
+
 proc addDotDependency(c: PPassContext, n: PNode): PNode =
   result = n
   let g = PGen(c)
@@ -35,11 +81,9 @@ proc addDotDependency(c: PPassContext, n: PNode): PNode =
   case n.kind
   of nkImportStmt:
     for i in 0..<n.len:
-      var imported = getModuleName(g.config, n[i])
-      addDependencyAux(b, g.module.name.s, imported)
+      addDependency(c, g, b, n[i])
   of nkFromStmt, nkImportExceptStmt:
-    var imported = getModuleName(g.config, n[0])
-    addDependencyAux(b, g.module.name.s, imported)
+    addDependency(c, g, b, n[0])
   of nkStmtList, nkBlockStmt, nkStmtListExpr, nkBlockExpr:
     for i in 0..<n.len: discard addDotDependency(c, n[i])
   else:

compiler/options.nim

@@ -850,7 +850,7 @@ when (NimMajor, NimMinor) < (1, 1) or not declared(isRelativeTo):
     let ret = relativePath(path, base)
     result = path.len > 0 and not ret.startsWith ".."
 
-const stdlibDirs = [
+const stdlibDirs* = [
   "pure", "core", "arch",
   "pure/collections",
   "pure/concurrency",