From 5f461184640db8b74f5bc4494acdb453f705af75 Mon Sep 17 00:00:00 2001
From: Jesse Szwedko <jesse@szwedko.me>
Date: Fri, 16 Apr 2021 09:47:34 -0400
Subject: [PATCH] fix(remap): Preserve type defs when assigning fields (#7118)

* fix(remap): Preserve type defs when assigning fields

Previously, remap would overwrite the type def of `.` whenever a new
field was assigned. That is:

```
.foo = 5
.bar = 6
```

Would result in the compiler only having type info for `.bar`.

This change causes it to merge the typedefs whenever a list of path
segments appears.

Signed-off-by: Jesse Szwedko <jesse@szwedko.me>
---
 docs/reference/remap.cue                         |  2 +-
 lib/vrl/compiler/src/expression/assignment.rs    | 16 +++++-----------
 .../tests/tests/issues/6792_lost_type_defs.vrl   |  7 +++++++
 3 files changed, 13 insertions(+), 12 deletions(-)
 create mode 100644 lib/vrl/tests/tests/issues/6792_lost_type_defs.vrl

diff --git a/docs/reference/remap.cue b/docs/reference/remap.cue
index 2367ffd12905c..cc0a54c05ed73 100644
--- a/docs/reference/remap.cue
+++ b/docs/reference/remap.cue
@@ -104,7 +104,7 @@ remap: #Remap & {
 				.tid = to_int!(.tid)
 
 				# Extract structured data
-				message_parts = split(.message, ", ", limit: 2) ?? []
+				message_parts = split(.message, ", ", limit: 2)
 				structured = parse_key_value(message_parts[1], key_value_delimiter: ":", field_delimiter: ",") ?? {}
 				.message = message_parts[0]
 				. = merge(., structured)
diff --git a/lib/vrl/compiler/src/expression/assignment.rs b/lib/vrl/compiler/src/expression/assignment.rs
index c522428e284a0..b649502d4a821 100644
--- a/lib/vrl/compiler/src/expression/assignment.rs
+++ b/lib/vrl/compiler/src/expression/assignment.rs
@@ -197,18 +197,12 @@ impl Target {
             new_type_def: TypeDef,
             path: &Option<Path>,
         ) -> TypeDef {
-            // If the assignment is into a specific index, we want to keep the
-            // existing type def, and only update the type def at the provided
-            // index.
-            let is_index_assignment = path
-                .as_ref()
-                .and_then(|p| p.segments().last().map(|s| s.is_index()))
-                .unwrap_or_default();
-
-            if is_index_assignment {
-                current_type_def.clone().merge_overwrite(new_type_def)
-            } else {
+            // If the assignment is onto root or has no path (root variable assignment), use the
+            // new type def, otherwise merge the type defs.
+            if path.as_ref().map(|path| path.is_root()).unwrap_or(true) {
                 new_type_def
+            } else {
+                current_type_def.clone().merge_overwrite(new_type_def)
             }
         }
 
diff --git a/lib/vrl/tests/tests/issues/6792_lost_type_defs.vrl b/lib/vrl/tests/tests/issues/6792_lost_type_defs.vrl
new file mode 100644
index 0000000000000..8634a0b97017b
--- /dev/null
+++ b/lib/vrl/tests/tests/issues/6792_lost_type_defs.vrl
@@ -0,0 +1,7 @@
+# https://github.com/timberio/vector/issues/6792#issuecomment-817986771
+# result: {"field1": "2020-01-01T00:00:00Z", "field2": 1577836800, "timestamp": "2020-01-01T00:00:00+00:00"}
+
+.timestamp = "2020-01-01T00:00:00+00:00"
+.field1 = parse_timestamp!(.timestamp, format: "%+")
+.field2 = to_int(.field1)
+.