Rust: Add a test for BuiltinTypes.

rust/ql/test/library-tests/elements/builtintypes/BuiltinTypes.expected

@@ -0,0 +1,17 @@
+| struct bool |  |
+| struct char |  |
+| struct f32 | FloatingPointType, NumericType |
+| struct f64 | FloatingPointType, NumericType |
+| struct i8 | IntegralType, NumericType |
+| struct i16 | IntegralType, NumericType |
+| struct i32 | IntegralType, NumericType |
+| struct i64 | IntegralType, NumericType |
+| struct i128 | IntegralType, NumericType |
+| struct isize | IntegralType, NumericType |
+| struct str |  |
+| struct u8 | IntegralType, NumericType |
+| struct u16 | IntegralType, NumericType |
+| struct u32 | IntegralType, NumericType |
+| struct u64 | IntegralType, NumericType |
+| struct u128 | IntegralType, NumericType |
+| struct usize | IntegralType, NumericType |

rust/ql/test/library-tests/elements/builtintypes/BuiltinTypes.ql

@@ -0,0 +1,14 @@
+import rust
+import codeql.rust.frameworks.stdlib.Builtins
+import codeql.rust.internal.Type
+
+string describe(BuiltinType t) {
+  (t instanceof NumericType and result = "NumericType")
+  or
+  (t instanceof IntegralType and result = "IntegralType")
+  or
+  (t instanceof FloatingPointType and result = "FloatingPointType")
+}
+
+from BuiltinType t
+select t.toString(), concat(describe(t), ", ")

rust/ql/test/library-tests/elements/builtintypes/Cargo.lock

@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "test"
+version = "0.0.1"

rust/ql/test/library-tests/elements/builtintypes/test.rs

@@ -0,0 +1,5 @@
+
+// --- tests ---
+
+fn test_types() {
+}