Rust: Path resolution before variable resolution

Author: hvitved

rust/ql/integration-tests/hello-workspace/path-resolution.ql

@@ -2,7 +2,7 @@ import rust
 import codeql.rust.internal.PathResolution
 import utils.test.PathResolutionInlineExpectationsTest
 
-query predicate resolveDollarCrate(RelevantPath p, Crate c) {
+query predicate resolveDollarCrate(PathExt p, Crate c) {
   c = resolvePath(p) and
   p.isDollarCrate() and
   p.fromSource() and

rust/ql/lib/codeql/rust/controlflow/internal/Completion.qll

@@ -1,5 +1,6 @@
 private import codeql.util.Boolean
 private import codeql.rust.controlflow.ControlFlowGraph
+private import codeql.rust.elements.internal.VariableImpl::Impl as VariableImpl
 private import rust
 
 newtype TCompletion =
@@ -123,13 +124,7 @@ class BooleanCompletion extends ConditionalCompletion, TBooleanCompletion {
  */
 private predicate cannotCauseMatchFailure(Pat pat) {
   pat instanceof RangePat or
-  // Identifier patterns that are in fact path patterns can cause failures. For
-  // instance `None`. Only if an `@ ...` part is present can we be sure that
-  // it's an actual identifier pattern. As a heuristic, if the identifier starts
-  // with a lower case letter, then we assume that it's an identifier.  This
-  // works for code that follows the Rust naming convention for enums and
-  // constants.
-  pat = any(IdentPat p | p.hasPat() or p.getName().getText().charAt(0).isLowercase()) or
+  pat = any(IdentPat p | p.hasPat() or VariableImpl::variableDecl(_, p.getName(), _)) or
   pat instanceof WildcardPat or
   pat instanceof RestPat or
   pat instanceof RefPat or

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

@@ -82,7 +82,7 @@ module Impl {
   }
 
   private predicate callHasTraitQualifier(CallExpr call, Trait qualifier) {
-    exists(RelevantPath qualifierPath |
+    exists(PathExt qualifierPath |
       callHasQualifier(call, _, qualifierPath) and
       qualifier = resolvePath(qualifierPath) and
       // When the qualifier is `Self` and resolves to a trait, it's inside a

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

@@ -5,6 +5,8 @@
  */
 
 private import codeql.rust.elements.internal.generated.Const
+private import codeql.rust.elements.internal.AstNodeImpl::Impl as AstNodeImpl
+private import codeql.rust.elements.internal.IdentPatImpl::Impl as IdentPatImpl
 private import codeql.rust.elements.internal.PathExprImpl::Impl as PathExprImpl
 private import codeql.rust.internal.PathResolution
 
@@ -36,14 +38,30 @@ module Impl {
    * }
    * ```
    */
-  class ConstAccess extends PathExprImpl::PathExpr {
+  abstract class ConstAccess extends AstNodeImpl::AstNode {
+    /** Gets the constant being accessed. */
+    abstract Const getConst();
+
+    override string getAPrimaryQlClass() { result = "ConstAccess" }
+  }
+
+  private class PathExprConstAccess extends ConstAccess, PathExprImpl::PathExpr {
     private Const c;
 
-    ConstAccess() { c = resolvePath(this.getPath()) }
+    PathExprConstAccess() { c = resolvePath(this.getPath()) }
 
-    /** Gets the constant being accessed. */
-    Const getConst() { result = c }
+    override Const getConst() { result = c }
 
-    override string getAPrimaryQlClass() { result = "ConstAccess" }
+    override string getAPrimaryQlClass() { result = ConstAccess.super.getAPrimaryQlClass() }
+  }
+
+  private class IdentPatConstAccess extends ConstAccess, IdentPatImpl::IdentPat {
+    private Const c;
+
+    IdentPatConstAccess() { c = resolvePath(this) }
+
+    override Const getConst() { result = c }
+
+    override string getAPrimaryQlClass() { result = ConstAccess.super.getAPrimaryQlClass() }
   }
 }

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

@@ -31,6 +31,8 @@ module Impl {
 
     override string toStringImpl() { result = this.getName() }
 
+    override string getAPrimaryQlClass() { result = "FormatTemplateVariableAccess" }
+
     /** Gets the name of the variable */
     string getName() { result = argument.getName() }
 

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

@@ -4,6 +4,7 @@
  * INTERNAL: Do not use.
  */
 
+private import rust
 private import codeql.rust.elements.internal.generated.PathExpr
 
 /**
@@ -25,5 +26,11 @@ module Impl {
     override string toStringImpl() { result = this.toAbbreviatedString() }
 
     override string toAbbreviatedString() { result = this.getPath().toStringImpl() }
+
+    override string getAPrimaryQlClass() {
+      if this instanceof VariableAccess
+      then result = "VariableAccess"
+      else result = super.getAPrimaryQlClass()
+    }
   }
 }

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

@@ -1,8 +1,9 @@
 private import rust
 private import codeql.rust.controlflow.ControlFlowGraph
+private import codeql.rust.internal.PathResolution as PathResolution
 private import codeql.rust.elements.internal.generated.ParentChild as ParentChild
+private import codeql.rust.elements.internal.AstNodeImpl::Impl as AstNodeImpl
 private import codeql.rust.elements.internal.PathImpl::Impl as PathImpl
-private import codeql.rust.elements.internal.PathExprBaseImpl::Impl as PathExprBaseImpl
 private import codeql.rust.elements.internal.FormatTemplateVariableAccessImpl::Impl as FormatTemplateVariableAccessImpl
 private import codeql.util.DenseRank
 
@@ -98,7 +99,7 @@ module Impl {
    * pattern.
    */
   cached
-  private predicate variableDecl(AstNode definingNode, Name name, string text) {
+  predicate variableDecl(AstNode definingNode, Name name, string text) {
     Cached::ref() and
     exists(SelfParam sp |
       name = sp.getName() and
@@ -117,11 +118,7 @@ module Impl {
         not exists(getOutermostEnclosingOrPat(pat)) and definingNode = name
       ) and
       text = name.getText() and
-      // exclude for now anything starting with an uppercase character, which may be a reference to
-      // an enum constant (e.g. `None`). This excludes static and constant variables (UPPERCASE),
-      // which we don't appear to recognize yet anyway. This also assumes programmers follow the
-      // naming guidelines, which they generally do, but they're not enforced.
-      not text.charAt(0).isUppercase() and
+      not PathResolution::identPatIsResolvable(pat) and
       // exclude parameters from functions without a body as these are trait method declarations
       // without implementations
       not exists(Function f | not f.hasBody() and f.getAParam().getPat() = pat) and
@@ -666,7 +663,7 @@ module Impl {
   }
 
   /** A variable access. */
-  class VariableAccess extends PathExprBaseImpl::PathExprBase {
+  class VariableAccess extends PathExprBase {
     private string name;
     private Variable v;
 
@@ -677,10 +674,6 @@ module Impl {
 
     /** Holds if this access is a capture. */
     predicate isCapture() { this.getEnclosingCfgScope() != v.getEnclosingCfgScope() }
-
-    override string toStringImpl() { result = name }
-
-    override string getAPrimaryQlClass() { result = "VariableAccess" }
   }
 
   /** Holds if `e` occurs in the LHS of an assignment or compound assignment. */
@@ -722,7 +715,7 @@ module Impl {
   }
 
   /** A nested function access. */
-  class NestedFunctionAccess extends PathExprBaseImpl::PathExprBase {
+  class NestedFunctionAccess extends PathExprBase {
     private Function f;
 
     NestedFunctionAccess() { nestedFunctionAccess(_, f, this) }

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

@@ -37,14 +37,17 @@ private module Cached {
     TFormatArgsArgIndex(Expr e) { e = any(FormatArgsArg a).getExpr() } or
     TItemNode(ItemNode i)
 
+  pragma[nomagic]
+  private predicate isMacroCallLocation(Location loc) { loc = any(MacroCall m).getLocation() }
+
   /**
    * Gets an element, of kind `kind`, that element `use` uses, if any.
    */
   cached
   Definition definitionOf(Use use, string kind) {
     result = use.getDefinition() and
     kind = use.getUseType() and
-    not result.getLocation() = any(MacroCall m).getLocation()
+    not isMacroCallLocation(result.getLocation())
   }
 }