Address review comments

rust/ql/lib/codeql/rust/internal/PathResolution.qll

@@ -655,6 +655,11 @@ private predicate fileModule(SourceFile f, string name, Folder folder) {
   )
 }
 
+/**
+ * Gets the `Meta` of the module `m`'s [path attribute][1].
+ *
+ * [1]: https://doc.rust-lang.org/reference/items/modules.html#r-items.mod.outlined.path
+ */
 private Meta getPathAttrMeta(Module m) {
   result = m.getAnAttr().getMeta() and
   result.getPath().getText() = "path"
@@ -725,7 +730,7 @@ private predicate pathAttrImport(Folder f, Module m, string relativePath) {
   )
 }
 
-private predicate append(Folder f, string relativePath) { pathAttrImport(f, _, relativePath) }
+private predicate shouldAppend(Folder f, string relativePath) { pathAttrImport(f, _, relativePath) }
 
 /** Holds if `m` is a `mod name;` item importing file `f`. */
 private predicate fileImport(Module m, SourceFile f) {
@@ -743,7 +748,7 @@ private predicate fileImport(Module m, SourceFile f) {
   or
   exists(Folder folder, string relativePath |
     pathAttrImport(folder, m, relativePath) and
-    f.getFile() = Folder::Append<append/2>::append(folder, relativePath)
+    f.getFile() = Folder::Append<shouldAppend/2>::append(folder, relativePath)
   )
 }
 

shared/util/codeql/util/FileSystem.qll

@@ -222,20 +222,27 @@ module Make<InputSig Input> {
   /** Provides logic related to `Folder`s. */
   module Folder {
     /** Holds if `relativePath` needs to be appended to `f`. */
-    signature predicate appendSig(Folder f, string relativePath);
+    signature predicate shouldAppendSig(Folder f, string relativePath);
 
     /** Provides the `append` predicate for appending a relative path onto a folder. */
-    module Append<appendSig/2 app> {
+    module Append<shouldAppendSig/2 shouldAppend> {
       pragma[nomagic]
       private string getComponent(string relativePath, int i) {
-        app(_, relativePath) and
+        shouldAppend(_, relativePath) and
         result = relativePath.replaceAll("\\", "/").regexpFind("[^/]+", i, _)
       }
 
+      private int getNumberOfComponents(string relativePath) {
+        result = strictcount(int i | exists(getComponent(relativePath, i)) | i)
+        or
+        relativePath = "" and
+        result = 0
+      }
+
       pragma[nomagic]
       private Container appendStep(Folder f, string relativePath, int i) {
         i = -1 and
-        app(f, relativePath) and
+        shouldAppend(f, relativePath) and
         result = f
         or
         exists(Container mid, string comp |
@@ -258,9 +265,9 @@ module Make<InputSig Input> {
        */
       pragma[nomagic]
       Container append(Folder f, string relativePath) {
-        exists(int components |
-          components = (-1).maximum(max(int comp | exists(getComponent(relativePath, comp)) | comp)) and
-          result = appendStep(f, relativePath, components)
+        exists(int last |
+          last = getNumberOfComponents(relativePath) - 1 and
+          result = appendStep(f, relativePath, last)
         )
       }
     }