Rust: Rename ContextType -> UnknownType

Author: hvitved

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

@@ -51,7 +51,7 @@ newtype TType =
   TSliceType() or
   TNeverType() or
   TPtrType() or
-  TContextType() or
+  TUnknownType() or
   TTupleTypeParameter(int arity, int i) { exists(TTuple(arity)) and i in [0 .. arity - 1] } or
   TTypeParamTypeParameter(TypeParam t) or
   TAssociatedTypeTypeParameter(TypeAlias t) { any(TraitItemNode trait).getAnAssocItem() = t } or
@@ -374,21 +374,27 @@ class PtrType extends Type, TPtrType {
 
 /**
  * A special pseudo type used to indicate that the actual type may have to be
- * inferred from a context.
+ * inferred by propagating type information back into call arguments.
  *
- * For example, a call like `Default::default()` is assigned this type, which
- * means that the actual type is to be inferred from the context in which the call
- * occurs.
+ * For example, in
  *
- * Context types are not restricted to root types, for example in a call like
+ * ```rust
+ * let x = Default::default();
+ * foo(x);
+ * ```
+ *
+ * `Default::default()` is assigned this type, which allows us to infer the actual
+ * type from the type of `foo`'s first parameter.
+ *
+ * Unknown types are not restricted to root types, for example in a call like
  * `Vec::new()` we assign this type at the type path corresponding to the type
  * parameter of `Vec`.
  *
- * Context types are used to restrict when type information is allowed to flow
+ * Unknown types are used to restrict when type information is allowed to flow
  * into call arguments (including method call receivers), in order to avoid
  * combinatorial explosions.
  */
-class ContextType extends Type, TContextType {
+class UnknownType extends Type, TUnknownType {
   override TypeParameter getPositionalTypeParameter(int i) { none() }
 
   override string toString() { result = "(context typed)" }

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

@@ -859,7 +859,7 @@ private module StructExprMatchingInput implements MatchingInputSig {
 
     pragma[nomagic]
     Type getTypeArgument(TypeArgumentPosition apos, TypePath path) {
-      // Handle constructions that use `Self{...}` syntax
+      // Handle constructions that use `Self {...}` syntax
       exists(TypeMention tm, TypePath path0 |
         tm = this.getStructPath() and
         result = tm.resolveTypeAt(path0) and
@@ -872,7 +872,7 @@ private module StructExprMatchingInput implements MatchingInputSig {
      * be inferred from the context.
      */
     pragma[nomagic]
-    predicate isContextTypedAt(DeclarationPosition pos, TypePath path) {
+    predicate hasUnknownTypeAt(DeclarationPosition pos, TypePath path) {
       exists(Declaration d, TypeParameter tp |
         d = this.getTarget() and
         pos.isStructPos() and
@@ -939,8 +939,8 @@ private Type inferStructExprType0(AstNode n, boolean isReturn, TypePath path) {
   |
     result = StructExprMatching::inferAccessType(a, apos, path)
     or
-    a.isContextTypedAt(apos, path) and
-    result = TContextType()
+    a.hasUnknownTypeAt(apos, path) and
+    result = TUnknownType()
   )
 }
 
@@ -1022,7 +1022,7 @@ private module ContextTyping {
      * at `pos` and `path` may have to be inferred from the context.
      */
     bindingset[this, i, target]
-    predicate isContextTypedAt(
+    predicate hasUnknownTypeAt(
       ImplOrTraitItemNode i, Function target, FunctionPosition pos, TypePath path
     ) {
       exists(TypeParameter tp |
@@ -1045,10 +1045,12 @@ private module ContextTyping {
   }
 
   pragma[nomagic]
-  private predicate isContextTyped(AstNode n, TypePath path) { inferType(n, path) = TContextType() }
+  private predicate hasUnknownTypeAt(AstNode n, TypePath path) {
+    inferType(n, path) = TUnknownType()
+  }
 
   pragma[nomagic]
-  private predicate isContextTyped(AstNode n) { isContextTyped(n, _) }
+  private predicate hasUnknownType(AstNode n) { hasUnknownTypeAt(n, _) }
 
   signature Type inferCallTypeSig(AstNode n, boolean isReturn, TypePath path);
 
@@ -1062,7 +1064,7 @@ private module ContextTyping {
     pragma[nomagic]
     private Type inferCallTypeFromContextCand(AstNode n, TypePath path, TypePath prefix) {
       result = inferCallType(n, false, path) and
-      isContextTyped(n) and
+      hasUnknownType(n) and
       prefix = path
       or
       exists(TypePath mid |
@@ -1077,7 +1079,7 @@ private module ContextTyping {
       or
       exists(TypePath prefix |
         result = inferCallTypeFromContextCand(n, path, prefix) and
-        isContextTyped(n, prefix)
+        hasUnknownTypeAt(n, prefix)
       )
     }
   }
@@ -1744,7 +1746,7 @@ private module MethodResolution {
     Type getTypeAt(TypePath path) {
       result = mc_.getACandidateReceiverTypeAtSubstituteLookupTraits(derefChain, borrow, path) and
       not result = TNeverType() and
-      not result = TContextType()
+      not result = TUnknownType()
     }
 
     pragma[nomagic]
@@ -2160,9 +2162,9 @@ private module MethodCallMatchingInput implements MatchingWithEnvironmentInputSi
      * from the context.
      */
     pragma[nomagic]
-    predicate isContextTypedAt(string derefChainBorrow, FunctionPosition pos, TypePath path) {
+    predicate hasUnknownTypeAt(string derefChainBorrow, FunctionPosition pos, TypePath path) {
       exists(ImplOrTraitItemNode i |
-        this.isContextTypedAt(i, this.getTarget(i, derefChainBorrow), pos, path)
+        this.hasUnknownTypeAt(i, this.getTarget(i, derefChainBorrow), pos, path)
       )
     }
   }
@@ -2180,8 +2182,8 @@ private Type inferMethodCallType0(
     (
       result = MethodCallMatching::inferAccessType(a, derefChainBorrow, apos, path0)
       or
-      a.isContextTypedAt(derefChainBorrow, apos, path0) and
-      result = TContextType()
+      a.hasUnknownTypeAt(derefChainBorrow, apos, path0) and
+      result = TUnknownType()
     )
   |
     if
@@ -2669,9 +2671,9 @@ private module NonMethodCallMatchingInput implements MatchingInputSig {
      * from the context.
      */
     pragma[nomagic]
-    predicate isContextTypedAt(FunctionPosition pos, TypePath path) {
+    predicate hasUnknownTypeAt(FunctionPosition pos, TypePath path) {
       exists(ImplOrTraitItemNode i |
-        this.isContextTypedAt(i,
+        this.hasUnknownTypeAt(i,
           [
             this.resolveCallTargetViaPathResolution().(NonMethodFunction),
             this.resolveCallTargetViaTypeInference(i),
@@ -2705,8 +2707,8 @@ private Type inferNonMethodCallType0(AstNode n, boolean isReturn, TypePath path)
   |
     result = NonMethodCallMatching::inferAccessType(a, apos, path)
     or
-    a.isContextTypedAt(apos, path) and
-    result = TContextType()
+    a.hasUnknownTypeAt(apos, path) and
+    result = TUnknownType()
   )
 }
 

rust/ql/lib/codeql/rust/internal/typeinference/BlanketImplementation.qll

@@ -93,7 +93,7 @@ module SatisfiesBlanketConstraint<
     Type getTypeAt(TypePath path) {
       result = at.getTypeAt(blanketPath.appendInverse(path)) and
       not result = TNeverType() and
-      not result = TContextType()
+      not result = TUnknownType()
     }
 
     string toString() { result = at.toString() + " [blanket at " + blanketPath.toString() + "]" }

rust/ql/lib/codeql/rust/internal/typeinference/FunctionType.qll

@@ -230,7 +230,7 @@ module ArgIsInstantiationOf<
     Type getTypeAt(TypePath path) {
       result = substituteLookupTraits(super.getTypeAt(path)) and
       not result = TNeverType() and
-      not result = TContextType()
+      not result = TUnknownType()
     }
   }
 

rust/ql/test/library-tests/type-inference/type-inference.ql

@@ -6,7 +6,7 @@ import TypeInference
 
 query predicate inferType(AstNode n, TypePath path, Type t) {
   t = TypeInference::inferType(n, path) and
-  t != TContextType() and
+  t != TUnknownType() and
   n.fromSource() and
   not n.isFromMacroExpansion() and
   not n instanceof IdentPat and // avoid overlap in the output with the underlying `Name` node