Rust: Remove elements superseded by attribute macro expansions

misc/codegen/templates/ql_db.mustache

@@ -29,9 +29,79 @@ module Raw {
     {{type}} {{getter}}({{#is_indexed}}int index{{/is_indexed}}) {
       {{tablename}}({{#tableparams}}{{^first}}, {{/first}}{{param}}{{/tableparams}})
     }
+    {{#is_indexed}}
+    /**
+     * Gets the number of {{doc_plural}}.
+    {{#internal}}
+     * INTERNAL: Do not use.
+    {{/internal}}
+     */
+    int getNumberOf{{plural}}() {
+      result = count(int i | {{tablename}}(this, i, _))
+    }
+    {{/is_indexed}}
     {{/synth}}
     {{/properties}}
   }
 
+
+  {{#final}}
+  private Element getImmediateChildOf{{name}}({{name}} e, int index) {
+    {{^has_children}}none(){{/has_children}}
+    {{#has_children}}
+    {{! n is the base offset 0, for ease of generation }}
+    {{! n<child> is constructed to be strictly greater than the indexes for <child> children }}
+        exists(int n{{#all_children}}, int n{{property.singular}}{{/all_children}} |
+            n = 0
+            {{#all_children}}
+                {{#property}}
+                {{#synth}}
+                       and
+                       n{{singular}} = n{{prev}}
+                {{/synth}}
+                {{^synth}}
+                    {{! n<child> is defined on top of the previous definition }}
+                    {{! for single and optional properties it adds 1 (regardless of whether the optional property exists) }}
+                    {{! for repeated it adds 1 + the maximum index (which works for repeated optional as well) }}
+                        and
+                        n{{singular}} = n{{prev}} {{^is_repeated}}+ 1{{/is_repeated}}{{#is_repeated}}+ e.getNumberOf{{plural}}(){{/is_repeated}}
+                {{/synth}}
+                {{/property}}
+            {{/all_children}} and (
+        none()
+        {{#all_children}}
+            {{#property}}
+            {{^synth}}
+                or
+                {{#is_repeated}}
+                    result = e.get{{singular}}(index - n{{prev}})
+                {{/is_repeated}}
+                {{^is_repeated}}
+                    index = n{{prev}} and result = e.get{{singular}}()
+                {{/is_repeated}}
+            {{/synth}}
+            {{/property}}
+        {{/all_children}}
+        ))
+    {{/has_children}}
+    }
+    {{/final}}
+
   {{/classes}}
+
+  /**
+   * Gets the immediate child indexed at `index`. Indexes are not guaranteed to be contiguous, but are guaranteed to be distinct.
+   */
+  pragma[nomagic]
+  Element getImmediateChild(Element e, int index) {
+  // why does this look more complicated than it should?
+  // * none() simplifies generation, as we can append `or ...` without a special case for the first item
+  none()
+  {{#classes}}
+      {{#final}}
+          or
+          result = getImmediateChildOf{{name}}(e, index)
+      {{/final}}
+  {{/classes}}
+  }
 }

misc/codegen/templates/ql_parent.mustache

@@ -23,7 +23,12 @@ private module Impl {
                         {{! for single and optional properties it adds 1 (regardless of whether the optional property exists) }}
                         {{! for repeated it adds 1 + the maximum index (which works for repeated optional as well) }}
                             and
-                            n{{singular}} = n{{prev}} + 1{{#is_repeated}}+ max(int i | i = -1 or exists(e.get{{#type_is_hideable}}Immediate{{/type_is_hideable}}{{singular}}(i)) | i){{/is_repeated}}
+                            {{#type_is_hideable}}
+                            n{{singular}} = n{{prev}} + 1{{#is_repeated}}+ max(int i | i = -1 or exists(e.getImmediate{{singular}}(i)) | i){{/is_repeated}}
+                            {{/type_is_hideable}}
+                            {{^type_is_hideable}}
+                            n{{singular}} = n{{prev}} {{^is_repeated}}+ 1{{/is_repeated}}{{#is_repeated}}+ e.getNumberOf{{plural}}(){{/is_repeated}}
+                            {{/type_is_hideable}}
                     {{/property}}
                 {{/all_children}} and (
             none()

misc/codegen/templates/ql_synth_types.mustache

@@ -32,9 +32,28 @@ module Synth {
   {{/root}}
   {{/non_final_classes}}
 
+  /**
+   * INTERNAL: Do not use.
+   *
+   * Gets the parent of synthetic element `e`.
+   */
+  Raw::{{root}} getSynthParent(T{{root}} e) {
+    none()
+    {{#final_classes}}
+    {{#is_fresh_synth}}
+    {{#has_params}}
+    or
+    e = T{{name}}({{#params}}{{#first}}result{{/first}}{{^first}}, _{{/first}}{{/params}})
+    {{/has_params}}
+    {{/is_fresh_synth}}
+    {{/final_classes}}
+  }
+
+
   {{#final_classes}}
   /**
    * INTERNAL: Do not use.
+   *
    * Converts a raw element to a synthesized `T{{name}}`, if possible.
    */
   T{{name}} convert{{name}}FromRaw(Raw::Element e) {

rust/ql/lib/codeql/rust/elements/internal/AstNodeImpl.qll

@@ -13,9 +13,9 @@ private import codeql.rust.controlflow.ControlFlowGraph
  */
 module Impl {
   private import rust
+  private import codeql.rust.elements.internal.ElementImpl::Impl as ElementImpl
   private import codeql.rust.elements.internal.generated.ParentChild
   private import codeql.rust.controlflow.ControlFlowGraph
-  private import codeql.rust.elements.internal.MacroCallImpl::Impl as MacroCallImpl
 
   /**
    * Gets the immediate parent of a non-`AstNode` element `e`.
@@ -71,21 +71,15 @@ module Impl {
     }
 
     /** Holds if this node is inside a macro expansion. */
-    predicate isInMacroExpansion() { MacroCallImpl::isInMacroExpansion(_, this) }
+    predicate isInMacroExpansion() { ElementImpl::MacroExpansion::isInMacroExpansion(this) }
 
     /**
      * Holds if this node exists only as the result of a macro expansion.
      *
      * This is the same as `isInMacroExpansion()`, but excludes AST nodes corresponding
-     * to macro arguments.
+     * to macro arguments, including attribute macro targets.
      */
-    pragma[nomagic]
-    predicate isFromMacroExpansion() {
-      exists(AstNode root |
-        MacroCallImpl::isInMacroExpansion(root, this) and
-        not this = root.(MacroCall).getATokenTreeNode()
-      )
-    }
+    predicate isFromMacroExpansion() { ElementImpl::MacroExpansion::isFromMacroExpansion(this) }
 
     /**
      * Gets a control flow node for this AST node, if any.

rust/ql/lib/codeql/rust/elements/internal/ElementImpl.qll

@@ -11,7 +11,115 @@ private import codeql.rust.elements.internal.generated.Element
  * be referenced directly.
  */
 module Impl {
+  private import rust
+  private import codeql.rust.elements.internal.generated.ParentChild
+  private import codeql.rust.elements.internal.generated.Synth
+  private import codeql.rust.elements.internal.generated.Raw
+  private import codeql.rust.elements.internal.LocationImpl
+
+  /**
+   * Provides logic for classifying elements with respect to macro expansions.
+   */
+  cached
+  module MacroExpansion {
+    /**
+     * Holds if `e` is superseded by an attribute macro expansion. That is, `e` is
+     * a transitive child of an item with an attribute macro expansion.
+     */
+    private predicate supersededByAttributeMacroExpansionRaw(Raw::Item item, Raw::Element e) {
+      exists(item.getAttributeMacroExpansion()) and
+      e = Raw::getImmediateChild(item, _) and
+      not e = item.getAttributeMacroExpansion() and
+      // Don't consider attributes themselves to be superseded.  E.g., in `#[a] fn
+      // f() {}` the macro expansion supersedes `fn f() {}` but not `#[a]`.
+      not e instanceof Raw::Attr
+      or
+      exists(Raw::Element parent |
+        e = Raw::getImmediateChild(parent, _) and
+        supersededByAttributeMacroExpansionRaw(item, parent)
+      )
+    }
+
+    private predicate isMacroExpansion(AstNode macro, AstNode expansion) {
+      expansion = macro.(MacroCall).getMacroCallExpansion()
+      or
+      expansion = macro.(Adt).getDeriveMacroExpansion(_)
+      or
+      expansion = macro.(Item).getAttributeMacroExpansion()
+    }
+
+    /**
+     * Gets the immediately enclosing macro invocation for element `e`, if any.
+     *
+     * The result is either a `MacroCall`, and `Adt` with a derive macro expansion, or
+     * an `Item` with an attribute macro expansion.
+     */
+    cached
+    AstNode getImmediatelyEnclosingMacroInvocation(Element e) {
+      isMacroExpansion(result, e)
+      or
+      exists(Element mid |
+        result = getImmediatelyEnclosingMacroInvocation(mid) and
+        mid = getImmediateParent(e) and
+        not isMacroExpansion(mid, e)
+      )
+    }
+
+    pragma[nomagic]
+    private predicate isAttributeMacroExpansionSourceLocation(Item i, Location l) {
+      exists(Raw::Locatable e, @location_default loc |
+        supersededByAttributeMacroExpansionRaw(Synth::convertElementToRaw(i), e) and
+        locatable_locations(e, loc) and
+        l = LocationImpl::TLocationDefault(loc)
+      )
+    }
+
+    /** Gets an AST node whose location is inside the token tree belonging to `mc`. */
+    pragma[nomagic]
+    private AstNode getATokenTreeNode(MacroCall mc) {
+      mc = getImmediatelyEnclosingMacroInvocation(result) and
+      mc.getTokenTree().getLocation().contains(result.getLocation())
+    }
+
+    /** Holds if `n` is inside a macro expansion. */
+    cached
+    predicate isInMacroExpansion(AstNode n) { exists(getImmediatelyEnclosingMacroInvocation(n)) }
+
+    /**
+     * Holds if `n` exists only as the result of a macro expansion.
+     *
+     * This is the same as `isInMacroExpansion(n)`, but excludes AST nodes corresponding
+     * to macro arguments, including attribute macro targets.
+     *
+     * Note: This predicate is a heuristic based on location information and may not be
+     * accurate in all cases.
+     */
+    cached
+    predicate isFromMacroExpansion(AstNode n) {
+      exists(AstNode macro |
+        macro = getImmediatelyEnclosingMacroInvocation(n) and
+        not n = getATokenTreeNode(macro) and
+        not isAttributeMacroExpansionSourceLocation(macro, n.getLocation())
+      )
+      or
+      isFromMacroExpansion(getImmediatelyEnclosingMacroInvocation(n))
+    }
+
+    cached
+    predicate isRelevantElement(Generated::Element e) {
+      exists(Raw::Element raw |
+        raw = Synth::convertElementToRaw(e) and
+        not supersededByAttributeMacroExpansionRaw(_, raw)
+      )
+      or
+      // Synthetic elements are relevant when their parent is
+      Synth::convertFormatArgsExprToRaw(_) = Synth::getSynthParent(e)
+    }
+  }
+
   class Element extends Generated::Element {
+    Element() { MacroExpansion::isRelevantElement(this) }
+
     override string toStringImpl() { result = this.getAPrimaryQlClass() }
 
     /**

rust/ql/lib/codeql/rust/elements/internal/ItemImpl.qll

@@ -1,4 +1,3 @@
-// generated by codegen, remove this comment if you wish to edit this file
 /**
  * This module provides a hand-modifiable wrapper around the generated class `Item`.
  *
@@ -12,6 +11,7 @@ private import codeql.rust.elements.internal.generated.Item
  * be referenced directly.
  */
 module Impl {
+  // the following QLdoc is generated: if you need to edit it, do it in the schema file
   /**
    * An item such as a function, struct, enum, etc.
    *
@@ -23,4 +23,10 @@ module Impl {
    * ```
    */
   class Item extends Generated::Item { }
+
+  private class ItemWithAttributeMacroExpansion extends Item {
+    ItemWithAttributeMacroExpansion() { this.hasAttributeMacroExpansion() }
+
+    override string toStringImpl() { result = "(item with attribute macro expansion)" }
+  }
 }

rust/ql/lib/codeql/rust/elements/internal/LocatableImpl.qll

@@ -5,6 +5,7 @@
  */
 
 import codeql.Locations
+private import codeql.rust.elements.internal.ElementImpl::Impl as ElementImpl
 private import codeql.rust.elements.internal.LocationImpl
 private import codeql.rust.elements.internal.generated.Locatable
 private import codeql.rust.elements.internal.generated.Synth
@@ -50,21 +51,12 @@ module Impl {
     locatable_locations(Synth::convertLocatableToRaw(l), result)
   }
 
-  private MacroCall getImmediatelyEnclosingMacroCall(AstNode n) {
-    result = n.getParentNode()
-    or
-    exists(AstNode mid |
-      result = getImmediatelyEnclosingMacroCall(mid) and
-      n.getParentNode() = mid and
-      not mid instanceof MacroCall
-    )
-  }
-
   /** Gets the non-synthesized location of `l`, if any. */
   LocationImpl::LocationDefault getLocationDefault(Locatable l) {
     result = LocationImpl::TLocationDefault(getDbLocation(l))
     or
     not exists(getDbLocation(l)) and
-    result = getLocationDefault(getImmediatelyEnclosingMacroCall(l))
+    result =
+      getLocationDefault(ElementImpl::MacroExpansion::getImmediatelyEnclosingMacroInvocation(l))
   }
 }