fix typedefs with query side-effects (vectordotdev#258)

lib/tests/tests/expressions/query/container_side_effect.vrl

@@ -0,0 +1,7 @@
+# result: {"type": { "bytes": true }, "value": "foo"}
+. = 3
+{. = "foo"}.x
+{
+    "value": .,
+    "type": type_def(.)
+}

lib/tests/tests/expressions/query/function_side_effect.vrl

@@ -0,0 +1,7 @@
+# result: {"type": { "null": true }, "value": null}
+. = 3
+del(.).x
+{
+    "value": .,
+    "type": type_def(.)
+}

src/compiler/expression/query.rs

@@ -129,14 +129,22 @@ impl Expression for Query {
     fn type_info(&self, state: &TypeState) -> TypeInfo {
         use Target::{Container, External, FunctionCall, Internal};
 
-        let result = match &self.target {
-            External(prefix) => state.external.kind(*prefix).at_path(&self.path).into(),
-            Internal(variable) => variable.type_def(state).at_path(&self.path),
-            FunctionCall(call) => call.type_def(state).at_path(&self.path),
-            Container(container) => container.type_def(state).at_path(&self.path),
-        };
-
-        TypeInfo::new(state, result)
+        match &self.target {
+            External(prefix) => {
+                let result = state.external.kind(*prefix).at_path(&self.path).into();
+                TypeInfo::new(state, result)
+            }
+            Internal(variable) => {
+                let result = variable.type_def(state).at_path(&self.path);
+                TypeInfo::new(state, result)
+            }
+            FunctionCall(call) => call
+                .type_info(state)
+                .map_result(|result| result.at_path(&self.path)),
+            Container(container) => container
+                .type_info(state)
+                .map_result(|result| result.at_path(&self.path)),
+        }
     }
 }
 

src/compiler/state.rs

@@ -17,6 +17,13 @@ impl TypeInfo {
             result,
         }
     }
+
+    pub fn map_result(self, f: impl FnOnce(TypeDef) -> TypeDef) -> Self {
+        Self {
+            state: self.state,
+            result: f(self.result),
+        }
+    }
 }
 
 impl From<&TypeState> for TypeState {