Rust: Handle (Enum::)Variant::<TypeArg> type mentions

Author: hvitved

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

@@ -509,12 +509,7 @@ private module StructExprMatchingInput implements MatchingInputSig {
       // The struct/enum type is supplied explicitly as a type qualifier, e.g.
       // `Foo<Bar>::Variant { ... }`.
       apos.isStructPos() and
-      exists(Path p, TypeMention tm |
-        p = this.getPath() and
-        if resolvePath(p) instanceof Variant then tm = p.getQualifier() else tm = p
-      |
-        result = tm.resolveTypeAt(path)
-      )
+      result = this.getPath().(TypeMention).resolveTypeAt(path)
     }
 
     Declaration getTarget() { result = resolvePath(this.getPath()) }
@@ -1242,12 +1237,7 @@ private module StructPatMatchingInput implements MatchingInputSig {
       // The struct/enum type is supplied explicitly as a type qualifier, e.g.
       // `let Foo<Bar>::Variant { ... } = ...`.
       apos.isStructPos() and
-      exists(Path p, TypeMention tm |
-        p = this.getPath() and
-        if resolvePath(p) instanceof Variant then tm = p.getQualifier() else tm = p
-      |
-        result = tm.resolveTypeAt(path)
-      )
+      result = this.getPath().(TypeMention).resolveTypeAt(path)
     }
 
     Declaration getTarget() { result = resolvePath(this.getPath()) }
@@ -1297,14 +1287,9 @@ private module TupleStructPatMatchingInput implements MatchingInputSig {
       result = inferType(this.getNodeAt(apos), path)
       or
       // The struct/enum type is supplied explicitly as a type qualifier, e.g.
-      // `let Option::<Foo>(x) = ...`.
+      // `let Option::<Foo>::Some(x) = ...`.
       apos.isSelf() and
-      exists(Path p, TypeMention tm |
-        p = this.getPath() and
-        if resolvePath(p) instanceof Variant then tm = p.getQualifier() else tm = p
-      |
-        result = tm.resolveTypeAt(path)
-      )
+      result = this.getPath().(TypeMention).resolveTypeAt(path)
     }
 
     Declaration getTarget() { result = resolvePath(this.getPath()) }

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

@@ -53,9 +53,13 @@ class SliceTypeReprMention extends TypeMention instanceof SliceTypeRepr {
 class PathTypeMention extends TypeMention, Path {
   TypeItemNode resolved;
 
-  PathTypeMention() { resolved = resolvePath(this) }
+  PathTypeMention() {
+    resolved = resolvePath(this)
+    or
+    resolved = resolvePath(this).(Variant).getEnum()
+  }
 
-  ItemNode getResolved() { result = resolved }
+  TypeItemNode getResolved() { result = resolved }
 
   pragma[nomagic]
   private TypeAlias getResolvedTraitAlias(string name) {
@@ -99,6 +103,10 @@ class PathTypeMention extends TypeMention, Path {
       this = node.getASelfPath() and
       result = node.(ImplItemNode).getSelfPath().getSegment().getGenericArgList().getTypeArg(i)
     )
+    or
+    // `Option::<i32>::Some` is valid in addition to `Option::Some::<i32>`
+    resolvePath(this) instanceof Variant and
+    result = this.getQualifier().getSegment().getGenericArgList().getTypeArg(i)
   }
 
   private TypeMention getPositionalTypeArgument(int i) {

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

@@ -2462,18 +2462,18 @@ pub mod pattern_matching {
             _ => (),
         }
 
-        let opt1 = Some(Default::default()); // $ MISSING: type=opt1:T.i32 method=default
+        let opt1 = Some(Default::default()); // $ type=opt1:T.i32 method=default
         #[rustfmt::skip]
         let _ = if let Some::<i32>(x) = opt1
         {
-            x; // $ MISSING: type=x:i32
+            x; // $ type=x:i32
         };
 
-        let opt2 = Some(Default::default()); // $ MISSING: type=opt2:T.i32 method=default
+        let opt2 = Some(Default::default()); // $ type=opt2:T.i32 method=default
         #[rustfmt::skip]
         let _ = if let Option::Some::<i32>(x) = opt2
         {
-            x; // $ MISSING: type=x:i32
+            x; // $ type=x:i32
         };
 
         let opt3 = Some(Default::default()); // $ type=opt3:T.i32 method=default

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

@@ -4303,13 +4303,27 @@ inferType
 | main.rs:2462:13:2462:13 | _ | T1.T2.&T | {EXTERNAL LOCATION} | str |
 | main.rs:2462:13:2462:13 | _ | T2 | {EXTERNAL LOCATION} | bool |
 | main.rs:2465:13:2465:16 | opt1 |  | {EXTERNAL LOCATION} | Option |
+| main.rs:2465:13:2465:16 | opt1 | T | {EXTERNAL LOCATION} | i32 |
 | main.rs:2465:20:2465:43 | Some(...) |  | {EXTERNAL LOCATION} | Option |
+| main.rs:2465:20:2465:43 | Some(...) | T | {EXTERNAL LOCATION} | i32 |
+| main.rs:2465:25:2465:42 | ...::default(...) |  | {EXTERNAL LOCATION} | i32 |
 | main.rs:2467:24:2467:37 | Some::<...>(...) |  | {EXTERNAL LOCATION} | Option |
+| main.rs:2467:24:2467:37 | Some::<...>(...) | T | {EXTERNAL LOCATION} | i32 |
+| main.rs:2467:36:2467:36 | x |  | {EXTERNAL LOCATION} | i32 |
 | main.rs:2467:41:2467:44 | opt1 |  | {EXTERNAL LOCATION} | Option |
+| main.rs:2467:41:2467:44 | opt1 | T | {EXTERNAL LOCATION} | i32 |
+| main.rs:2469:13:2469:13 | x |  | {EXTERNAL LOCATION} | i32 |
 | main.rs:2472:13:2472:16 | opt2 |  | {EXTERNAL LOCATION} | Option |
+| main.rs:2472:13:2472:16 | opt2 | T | {EXTERNAL LOCATION} | i32 |
 | main.rs:2472:20:2472:43 | Some(...) |  | {EXTERNAL LOCATION} | Option |
+| main.rs:2472:20:2472:43 | Some(...) | T | {EXTERNAL LOCATION} | i32 |
+| main.rs:2472:25:2472:42 | ...::default(...) |  | {EXTERNAL LOCATION} | i32 |
 | main.rs:2474:24:2474:45 | ...::Some::<...>(...) |  | {EXTERNAL LOCATION} | Option |
+| main.rs:2474:24:2474:45 | ...::Some::<...>(...) | T | {EXTERNAL LOCATION} | i32 |
+| main.rs:2474:44:2474:44 | x |  | {EXTERNAL LOCATION} | i32 |
 | main.rs:2474:49:2474:52 | opt2 |  | {EXTERNAL LOCATION} | Option |
+| main.rs:2474:49:2474:52 | opt2 | T | {EXTERNAL LOCATION} | i32 |
+| main.rs:2476:13:2476:13 | x |  | {EXTERNAL LOCATION} | i32 |
 | main.rs:2479:13:2479:16 | opt3 |  | {EXTERNAL LOCATION} | Option |
 | main.rs:2479:13:2479:16 | opt3 | T | {EXTERNAL LOCATION} | i32 |
 | main.rs:2479:20:2479:43 | Some(...) |  | {EXTERNAL LOCATION} | Option |