Rust: Infer range expressions certainly and support full ranges

rust/ql/lib/codeql/rust/elements/RangeExprExt.qll

@@ -46,6 +46,20 @@ final class RangeFromToExpr extends RangeExpr {
   }
 }
 
+/**
+ * A range-full expression. For example:
+ * ```rust
+ * let x = ..;
+ * ```
+ */
+final class RangeFullExpr extends RangeExpr {
+  RangeFullExpr() {
+    this.getOperatorName() = ".." and
+    not this.hasStart() and
+    not this.hasEnd()
+  }
+}
+
 /**
  * A range-inclusive expression. For example:
  * ```rust

rust/ql/lib/codeql/rust/frameworks/stdlib/Stdlib.qll

@@ -94,6 +94,16 @@ class RangeToStruct extends Struct {
   StructField getEnd() { result = this.getStructField("end") }
 }
 
+/**
+ * The [`RangeFull` struct][1].
+ *
+ * [1]: https://doc.rust-lang.org/core/ops/struct.RangeFull.html
+ */
+class RangeFullStruct extends Struct {
+  pragma[nomagic]
+  RangeFullStruct() { this.getCanonicalPath() = "core::ops::range::RangeFull" }
+}
+
 /**
  * The [`RangeInclusive` struct][1].
  *

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

@@ -385,6 +385,9 @@ private module CertainTypeInference {
     or
     result = inferLogicalOperationType(n, path)
     or
+    result = inferRangeExprType(n) and
+    path.isEmpty()
+    or
     result = inferTupleRootType(n) and
     path.isEmpty()
     or
@@ -463,6 +466,9 @@ private Struct getRangeType(RangeExpr re) {
   re instanceof RangeToExpr and
   result instanceof RangeToStruct
   or
+  re instanceof RangeFullExpr and
+  result instanceof RangeFullStruct
+  or
   re instanceof RangeFromToExpr and
   result instanceof RangeStruct
   or
@@ -2402,9 +2408,6 @@ private module Cached {
       or
       result = inferAwaitExprType(n, path)
       or
-      result = inferRangeExprType(n) and
-      path.isEmpty()
-      or
       result = inferIndexExprType(n, path)
       or
       result = inferForLoopExprType(n, path)

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

@@ -2332,7 +2332,7 @@ mod loops {
         for u in [0u8..10] {} // $ type=u:Range type=u:Idx.u8
         let range = 0..10; // $ type=range:Range type=range:Idx.i32
         for i in range {} // $ type=i:i32
-        let range_full = ..; // $ MISSING: type=range_full:RangeFull
+        let range_full = ..; // $ type=range_full:RangeFull
         for i in &[1i64, 2i64, 3i64][range_full] {} // $ target=index MISSING: type=i:&T.i64
 
         let range1 = // $ type=range1:Range type=range1:Idx.u16

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

@@ -4367,6 +4367,8 @@ inferType
 | main.rs:2334:13:2334:13 | i |  | {EXTERNAL LOCATION} | i32 |
 | main.rs:2334:18:2334:22 | range |  | {EXTERNAL LOCATION} | Range |
 | main.rs:2334:18:2334:22 | range | Idx | {EXTERNAL LOCATION} | i32 |
+| main.rs:2335:13:2335:22 | range_full |  | {EXTERNAL LOCATION} | RangeFull |
+| main.rs:2335:26:2335:27 | .. |  | {EXTERNAL LOCATION} | RangeFull |
 | main.rs:2336:13:2336:13 | i |  | {EXTERNAL LOCATION} | Item |
 | main.rs:2336:18:2336:48 | &... |  | file://:0:0:0:0 | & |
 | main.rs:2336:19:2336:36 | [...] |  | file://:0:0:0:0 | [] |
@@ -4374,6 +4376,7 @@ inferType
 | main.rs:2336:20:2336:23 | 1i64 |  | {EXTERNAL LOCATION} | i64 |
 | main.rs:2336:26:2336:29 | 2i64 |  | {EXTERNAL LOCATION} | i64 |
 | main.rs:2336:32:2336:35 | 3i64 |  | {EXTERNAL LOCATION} | i64 |
+| main.rs:2336:38:2336:47 | range_full |  | {EXTERNAL LOCATION} | RangeFull |
 | main.rs:2338:13:2338:18 | range1 |  | {EXTERNAL LOCATION} | Range |
 | main.rs:2338:13:2338:18 | range1 | Idx | {EXTERNAL LOCATION} | u16 |
 | main.rs:2339:9:2342:9 | ...::Range {...} |  | {EXTERNAL LOCATION} | Range |