Rust: Move inferArrayExprType logic into typeEquality predicate.

Author: geoffw0

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

@@ -287,6 +287,16 @@ private predicate typeEquality(AstNode n1, TypePath prefix1, AstNode n2, TypePat
       prefix2.isEmpty()
     )
   )
+  or
+  // an array list expression (`[1, 2, 3]`) has the type of the first (any) element
+  n1.(ArrayListExpr).getExpr(0) = n2 and
+  prefix1 = TypePath::singleton(TArrayTypeParameter()) and
+  prefix2.isEmpty()
+  or
+  // an array repeat expression (`[1; 3]`) has the type of the repeat operand
+  n1.(ArrayRepeatExpr).getRepeatOperand() = n2 and
+  prefix1 = TypePath::singleton(TArrayTypeParameter()) and
+  prefix2.isEmpty()
 }
 
 pragma[nomagic]
@@ -1124,23 +1134,6 @@ private Type inferIndexExprType(IndexExpr ie, TypePath path) {
   )
 }
 
-pragma[nomagic]
-private Type inferArrayExprType(ArrayExpr ae, TypePath path) {
-  // an array list expression (`[1, 2, 3]`) has the type of the first (any) element
-  exists(Type type0, TypePath path0 |
-    type0 = inferType(ae.(ArrayListExpr).getExpr(0), path0) and
-    result = type0 and
-    path = TypePath::cons(any(ArrayTypeParameter tp), path0)
-  )
-  or
-  // an array repeat expression (`[1; 3]`) has the type of the repeat operand
-  exists(Type type0, TypePath path0 |
-    type0 = inferType(ae.(ArrayRepeatExpr).getRepeatOperand(), path0) and
-    result = type0 and
-    path = TypePath::cons(any(ArrayTypeParameter tp), path0)
-  )
-}
-
 pragma[nomagic]
 private Type inferForLoopExprType(AstNode n, TypePath path) {
   // type of iterable -> type of pattern (loop variable)
@@ -1470,8 +1463,6 @@ private module Cached {
     or
     result = inferIndexExprType(n, path)
     or
-    result = inferArrayExprType(n, path)
-    or
     result = inferForLoopExprType(n, path)
   }
 }

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

@@ -2685,6 +2685,7 @@ inferType
 | main.rs:1840:31:1840:39 | [...] | [T;...] | {EXTERNAL LOCATION} | i32 |
 | main.rs:1840:31:1840:39 | [...] | [T;...] | {EXTERNAL LOCATION} | u32 |
 | main.rs:1840:32:1840:32 | 1 |  | {EXTERNAL LOCATION} | i32 |
+| main.rs:1840:32:1840:32 | 1 |  | {EXTERNAL LOCATION} | u32 |
 | main.rs:1840:35:1840:35 | 2 |  | {EXTERNAL LOCATION} | i32 |
 | main.rs:1840:38:1840:38 | 3 |  | {EXTERNAL LOCATION} | i32 |
 | main.rs:1841:13:1841:13 | u |  | {EXTERNAL LOCATION} | i32 |
@@ -2700,6 +2701,7 @@ inferType
 | main.rs:1843:31:1843:36 | [1; 3] | [T;...] | {EXTERNAL LOCATION} | i32 |
 | main.rs:1843:31:1843:36 | [1; 3] | [T;...] | {EXTERNAL LOCATION} | u64 |
 | main.rs:1843:32:1843:32 | 1 |  | {EXTERNAL LOCATION} | i32 |
+| main.rs:1843:32:1843:32 | 1 |  | {EXTERNAL LOCATION} | u64 |
 | main.rs:1843:35:1843:35 | 3 |  | {EXTERNAL LOCATION} | i32 |
 | main.rs:1844:13:1844:13 | u |  | {EXTERNAL LOCATION} | i32 |
 | main.rs:1844:13:1844:13 | u |  | {EXTERNAL LOCATION} | u64 |