Do not output undefined for nullable fields within @throwOnFieldError and @catch

compiler/crates/relay-compiler/tests/relay_compiler_integration/fixtures/error_handling_fragment.expected

@@ -17,7 +17,7 @@ type User { name: String }
 ==================================== OUTPUT ===================================
 //- __generated__/foo.graphql.js
 /**
- * <auto-generated> SignedSource<<aa8a9fd716975ca122b77708a6fca791>>
+ * <auto-generated> SignedSource<<70a7a244e5796d4e6e9f2fbcd76c50f0>>
  * @flow
  * @lightSyntaxTransform
  * @nogrep
@@ -32,7 +32,7 @@ import type { Fragment, ReaderFragment } from 'relay-runtime';
 import type { FragmentType } from "relay-runtime";
 declare export opaque type foo$fragmentType: FragmentType;
 export type foo$data = {|
-  +name: ?string,
+  +name: string | null,
   +$fragmentType: foo$fragmentType,
 |};
 export type foo$key = {

compiler/crates/relay-compiler/tests/relay_compiler_integration/fixtures/error_handling_query.expected

@@ -19,7 +19,7 @@ type User { name: String }
 ==================================== OUTPUT ===================================
 //- __generated__/fooQuery.graphql.js
 /**
- * <auto-generated> SignedSource<<9b5cf0134e02913bc0d65df99f7ff0c3>>
+ * <auto-generated> SignedSource<<2850659094fb71d3762177cc38cd028d>>
  * @flow
  * @lightSyntaxTransform
  * @nogrep
@@ -33,9 +33,9 @@ type User { name: String }
 import type { ConcreteRequest, Query } from 'relay-runtime';
 export type fooQuery$variables = {||};
 export type fooQuery$data = {|
-  +me: ?{|
-    +name: ?string,
-  |},
+  +me: {|
+    +name: string | null,
+  |} | null,
 |};
 export type fooQuery = {|
   response: fooQuery$data,

compiler/crates/relay-compiler/tests/relay_compiler_integration/fixtures/relay_resolvers_in_throw_on_field_error.expected

@@ -164,7 +164,7 @@ export default ((node/*: any*/)/*: Fragment<
 
 //- __generated__/fooQuery.graphql.js
 /**
- * <auto-generated> SignedSource<<3313eddbfdd22f715c9f61877c3934fc>>
+ * <auto-generated> SignedSource<<993d76639831b1e563cb29101f10f1c9>>
  * @flow
  * @lightSyntaxTransform
  * @nogrep
@@ -185,9 +185,9 @@ import {clientUser as queryClientUserResolverType} from "foo";
 |});
 export type fooQuery$variables = {||};
 export type fooQuery$data = {|
-  +clientUser: ?{|
+  +clientUser: {|
     +id: string,
-  |},
+  |} | null,
 |};
 export type fooQuery = {|
   response: fooQuery$data,

compiler/crates/relay-compiler/tests/relay_compiler_integration/fixtures/semantic_null_require_bubbling.expected

@@ -24,7 +24,7 @@ type Person {
 ==================================== OUTPUT ===================================
 //- __generated__/PersonComponentFragment.graphql.js
 /**
- * <auto-generated> SignedSource<<dd96467e5b9c67cd6e9fef4590fc9adb>>
+ * <auto-generated> SignedSource<<0b312efbb631920c43da94a7f1c6bcff>>
  * @flow
  * @lightSyntaxTransform
  * @nogrep
@@ -39,9 +39,9 @@ import type { Fragment, ReaderFragment } from 'relay-runtime';
 import type { FragmentType } from "relay-runtime";
 declare export opaque type PersonComponentFragment$fragmentType: FragmentType;
 export type PersonComponentFragment$data = {|
-  +some_person: ?{|
+  +some_person: {|
     +name: string,
-  |},
+  |} | null,
   +$fragmentType: PersonComponentFragment$fragmentType,
 |};
 export type PersonComponentFragment$key = {

compiler/crates/relay-typegen/src/flow.rs

@@ -9,6 +9,7 @@ use std::fmt::Result as FmtResult;
 use std::fmt::Write;
 
 use ::intern::string_key::StringKey;
+use intern::intern;
 use itertools::Itertools;
 
 use crate::writer::AST;
@@ -48,6 +49,7 @@ impl Writer for FlowPrinter {
             AST::Union(members) => self.write_union(members),
             AST::ReadOnlyArray(of_type) => self.write_read_only_array(of_type),
             AST::Nullable(of_type) => self.write_nullable(of_type),
+            AST::Optional(of_type) => self.write_optional(of_type),
             AST::NonNullable(of_type) => self.write_non_nullable(of_type),
             AST::ExactObject(props) => self.write_object(props, true),
             AST::InexactObject(props) => self.write_object(props, false),
@@ -212,6 +214,20 @@ impl FlowPrinter {
     }
 
     fn write_nullable(&mut self, of_type: &AST) -> FmtResult {
+        let null_type = AST::RawType(intern!("null"));
+        if let AST::Union(members) = of_type {
+            let mut new_members = Vec::with_capacity(members.len() + 1);
+            new_members.extend_from_slice(members);
+            new_members.push(null_type);
+            self.write_union(&new_members)?;
+        } else {
+            let members = vec![of_type.clone(), null_type];
+            self.write_union(&members)?;
+        }
+        Ok(())
+    }
+
+    fn write_optional(&mut self, of_type: &AST) -> FmtResult {
         write!(&mut self.result, "?")?;
         match of_type {
             AST::Union(members) if members.len() > 1 => {
@@ -386,8 +402,6 @@ impl FlowPrinter {
 
 #[cfg(test)]
 mod tests {
-    use intern::intern;
-
     use super::*;
     use crate::writer::ExactObject;
     use crate::writer::InexactObject;
@@ -426,18 +440,33 @@ mod tests {
         );
     }
 
+    #[test]
+    fn optional_type() {
+        assert_eq!(
+            print_type(&AST::Optional(Box::new(AST::String))),
+            "?string".to_string()
+        );
+
+        assert_eq!(
+            print_type(&AST::Optional(Box::new(AST::Union(SortedASTList::new(
+                vec![AST::String, AST::Number,],
+            ))))),
+            "?(string | number)"
+        )
+    }
+
     #[test]
     fn nullable_type() {
         assert_eq!(
             print_type(&AST::Nullable(Box::new(AST::String))),
-            "?string".to_string()
+            "string | null".to_string()
         );
 
         assert_eq!(
             print_type(&AST::Nullable(Box::new(AST::Union(SortedASTList::new(
                 vec![AST::String, AST::Number,],
             ))))),
-            "?(string | number)"
+            "string | number | null"
         )
     }
 

compiler/crates/relay-typegen/src/type_selection.rs

@@ -138,6 +138,7 @@ pub(crate) struct TypeSelectionLinkedField {
     pub(crate) conditional: bool,
     pub(crate) concrete_type: Option<Type>,
     pub(crate) is_result_type: bool,
+    pub(crate) emit_semantic_type: bool,
 }
 
 #[derive(Debug, Clone)]

compiler/crates/relay-typegen/src/typescript.rs

@@ -62,6 +62,7 @@ impl Writer for TypeScriptPrinter {
             AST::Union(members) => self.write_union(members),
             AST::ReadOnlyArray(of_type) => self.write_read_only_array(of_type),
             AST::Nullable(of_type) => self.write_nullable(of_type),
+            AST::Optional(of_type) => self.write_optional(of_type),
             AST::NonNullable(of_type) => self.write_non_nullable(of_type),
             AST::ExactObject(object) => self.write_object(object),
             AST::InexactObject(object) => self.write_object(object),
@@ -217,6 +218,20 @@ impl TypeScriptPrinter {
     }
 
     fn write_nullable(&mut self, of_type: &AST) -> FmtResult {
+        let null_type = AST::RawType(intern!("null"));
+        if let AST::Union(members) = of_type {
+            let mut new_members = Vec::with_capacity(members.len() + 1);
+            new_members.extend_from_slice(members);
+            new_members.push(null_type);
+            self.write_union(&new_members)?;
+        } else {
+            let union_members = vec![of_type.clone(), null_type];
+            self.write_union(&union_members)?;
+        }
+        Ok(())
+    }
+
+    fn write_optional(&mut self, of_type: &AST) -> FmtResult {
         let null_type = AST::RawType(intern!("null"));
         let undefined_type = AST::RawType(intern!("undefined"));
         if let AST::Union(members) = of_type {
@@ -447,18 +462,33 @@ mod tests {
         );
     }
 
+    #[test]
+    fn optional_type() {
+        assert_eq!(
+            print_type(&AST::Optional(Box::new(AST::String))),
+            "string | null | undefined".to_string()
+        );
+
+        assert_eq!(
+            print_type(&AST::Optional(Box::new(AST::Union(SortedASTList::new(
+                vec![AST::String, AST::Number],
+            ))))),
+            "string | number | null | undefined"
+        )
+    }
+
     #[test]
     fn nullable_type() {
         assert_eq!(
             print_type(&AST::Nullable(Box::new(AST::String))),
-            "string | null | undefined".to_string()
+            "string | null".to_string()
         );
 
         assert_eq!(
             print_type(&AST::Nullable(Box::new(AST::Union(SortedASTList::new(
                 vec![AST::String, AST::Number],
             ))))),
-            "string | number | null | undefined"
+            "string | number | null"
         )
     }