feat(rome_json_formatter): Fallback to Verbatim for nodes with syntax…

… errors

Some prettier tests for JSON5 are failing after implementing array formatting in #4064

The tests fail because the formatting returns a `FormatError::SyntaxError` if a mandatory child node is missing but the error is never handled by the JSON formatting.

This PR fixes this by

* Gracefully handle missing values on the root value by calling into verbatim formatting if that's the case
* Use `format_or_verbatim` when formatting values

I had to pull out the `format_or_verbatim` from the `rome_js_formatter` and move it to `rome_formatter` so that it can be re-used between js and json formatting.

crates/rome_formatter/src/prelude.rs

@@ -11,7 +11,9 @@ pub use crate::trivia::{
 pub use crate::diagnostics::FormatError;
 pub use crate::format_element::document::Document;
 pub use crate::format_element::tag::{LabelId, Tag, TagKind};
-pub use crate::verbatim::{format_bogus_node, format_suppressed_node, format_verbatim_node};
+pub use crate::verbatim::{
+    format_bogus_node, format_or_verbatim, format_suppressed_node, format_verbatim_node,
+};
 
 pub use crate::{
     best_fitting, dbg_write, format, format_args, write, Buffer as _, BufferExtensions, Format,

crates/rome_formatter/src/verbatim.rs

@@ -1,8 +1,8 @@
 use crate::format_element::tag::VerbatimKind;
 use crate::prelude::*;
 use crate::trivia::{FormatLeadingComments, FormatTrailingComments};
-use crate::{write, CstFormatContext};
-use rome_rowan::{Direction, Language, SyntaxElement, SyntaxNode, TextRange};
+use crate::{write, CstFormatContext, FormatWithRule};
+use rome_rowan::{AstNode, Direction, Language, SyntaxElement, SyntaxNode, TextRange};
 
 /// "Formats" a node according to its original formatting in the source text. Being able to format
 /// a node "as is" is useful if a node contains syntax errors. Formatting a node with syntax errors
@@ -167,3 +167,39 @@ pub fn format_suppressed_node<L: Language>(node: &SyntaxNode<L>) -> FormatVerbat
         format_comments: true,
     }
 }
+
+/// Formats an object using its [`Format`] implementation but falls back to printing the object as
+/// it is in the source document if formatting it returns an [`FormatError::SyntaxError`].
+pub const fn format_or_verbatim<F>(inner: F) -> FormatNodeOrVerbatim<F> {
+    FormatNodeOrVerbatim { inner }
+}
+
+/// Formats a node or falls back to verbatim printing if formating this node fails.
+#[derive(Copy, Clone)]
+pub struct FormatNodeOrVerbatim<F> {
+    inner: F,
+}
+
+impl<F, Context, Item> Format<Context> for FormatNodeOrVerbatim<F>
+where
+    F: FormatWithRule<Context, Item = Item>,
+    Item: AstNode,
+    Context: CstFormatContext<Language = Item::Language>,
+{
+    fn fmt(&self, f: &mut Formatter<Context>) -> FormatResult<()> {
+        let snapshot = Formatter::state_snapshot(f);
+
+        match self.inner.fmt(f) {
+            Ok(result) => Ok(result),
+
+            Err(FormatError::SyntaxError) => {
+                f.restore_state_snapshot(snapshot);
+
+                // Lists that yield errors are formatted as they were suppressed nodes.
+                // Doing so, the formatter formats the nodes/tokens as is.
+                format_suppressed_node(self.inner.item().syntax()).fmt(f)
+            }
+            Err(err) => Err(err),
+        }
+    }
+}

crates/rome_js_formatter/src/js/lists/class_member_list.rs

@@ -11,7 +11,7 @@ impl FormatRule<JsClassMemberList> for FormatJsClassMemberList {
         let mut join = f.join_nodes_with_hardline();
 
         for member in node {
-            join.entry(member.syntax(), &format_or_verbatim(&member));
+            join.entry(member.syntax(), &format_or_verbatim(member.format()));
         }
 
         join.finish()

crates/rome_js_formatter/src/js/lists/module_item_list.rs

@@ -16,7 +16,10 @@ impl FormatRule<JsModuleItemList> for FormatJsModuleItemList {
                     join.entry_no_separator(&empty.format());
                 }
                 _ => {
-                    join.entry(module_item.syntax(), &format_or_verbatim(&module_item));
+                    join.entry(
+                        module_item.syntax(),
+                        &format_or_verbatim(module_item.format()),
+                    );
                 }
             }
         }

crates/rome_js_formatter/src/js/lists/statement_list.rs

@@ -16,7 +16,7 @@ impl FormatRule<JsStatementList> for FormatJsStatementList {
                     join.entry_no_separator(&empty.format());
                 }
                 _ => {
-                    join.entry(statement.syntax(), &format_or_verbatim(&statement));
+                    join.entry(statement.syntax(), &format_or_verbatim(statement.format()));
                 }
             }
         }

crates/rome_js_formatter/src/js/lists/switch_case_list.rs

@@ -11,7 +11,7 @@ impl FormatRule<JsSwitchCaseList> for FormatJsSwitchCaseList {
         let mut join = f.join_nodes_with_hardline();
 
         for case in node {
-            join.entry(case.syntax(), &format_or_verbatim(&case));
+            join.entry(case.syntax(), &format_or_verbatim(case.format()));
         }
 
         join.finish()

crates/rome_js_formatter/src/lib.rs

@@ -173,7 +173,6 @@ pub mod utils;
 
 #[rustfmt::skip]
 mod generated;
-mod builders;
 pub mod comments;
 pub mod context;
 mod parentheses;

crates/rome_js_formatter/src/prelude.rs

@@ -2,8 +2,8 @@
 //! when implementing a syntax formatter.
 
 pub(crate) use crate::{
-    builders::format_or_verbatim, comments::JsComments, AsFormat as _, FormatNodeRule,
-    FormattedIterExt, JsFormatContext, JsFormatter,
+    comments::JsComments, AsFormat as _, FormatNodeRule, FormattedIterExt, JsFormatContext,
+    JsFormatter,
 };
 pub use rome_formatter::prelude::*;
 pub use rome_formatter::separated::TrailingSeparator;

crates/rome_json_formatter/src/json/auxiliary/member.rs

@@ -1,19 +1,25 @@
 use crate::prelude::*;
 use rome_formatter::{format_args, write};
-use rome_json_syntax::JsonMember;
+use rome_json_syntax::{JsonMember, JsonMemberFields};
 
 #[derive(Debug, Clone, Default)]
 pub(crate) struct FormatJsonMember;
 
 impl FormatNodeRule<JsonMember> for FormatJsonMember {
     fn fmt_fields(&self, node: &JsonMember, f: &mut JsonFormatter) -> FormatResult<()> {
+        let JsonMemberFields {
+            name,
+            colon_token,
+            value,
+        } = node.as_fields();
+
         write!(
             f,
             [group(&format_args![
-                &node.name().format(),
-                node.colon_token().format(),
+                &name.format(),
+                colon_token.format(),
                 space(),
-                node.value().format()
+                format_or_verbatim(value?.format())
             ])]
         )
     }

crates/rome_json_formatter/src/json/auxiliary/root.rs

@@ -9,13 +9,21 @@ impl FormatNodeRule<JsonRoot> for FormatJsonRoot {
     fn fmt_fields(&self, node: &JsonRoot, f: &mut JsonFormatter) -> FormatResult<()> {
         let JsonRootFields { value, eof_token } = node.as_fields();
 
-        write!(
-            f,
-            [
-                value.format(),
-                format_removed(&eof_token?),
-                hard_line_break()
-            ]
-        )
+        match &value {
+            Ok(value) => {
+                write!(
+                    f,
+                    [
+                        format_or_verbatim(value.format()),
+                        format_removed(&eof_token?),
+                        hard_line_break()
+                    ]
+                )
+            }
+            // Don't fail formatting if the root contains no root value
+            Err(_) => {
+                write!(f, [format_verbatim_node(node.syntax())])
+            }
+        }
     }
 }

crates/rome_json_formatter/tests/specs/json/empty.json.snap

@@ -0,0 +1,32 @@
+---
+source: crates/rome_formatter_test/src/snapshot_builder.rs
+info: "json\\empty.json"
+---
+
+# Input
+
+```json
+
+```
+
+
+=============================
+
+# Outputs
+
+## Output 1
+
+-----
+Indent style: Tab
+Line width: 80
+-----
+
+```json
+```
+
+
+
+## Unimplemented nodes/tokens
+
+"" => 0..0
+

crates/rome_json_formatter/tests/specs/json/object/missing_value.json

@@ -0,0 +1,9 @@
+{
+	"missing_value": {
+		"a":,
+		"b": 1
+	},
+
+	"b": 1,
+	"c": "2", "d": 3
+}

crates/rome_json_formatter/tests/specs/json/object/missing_value.json.snap

@@ -0,0 +1,46 @@
+---
+source: crates/rome_formatter_test/src/snapshot_builder.rs
+info: "json\\object\\missing_value.json"
+---
+
+# Input
+
+```json
+{
+	"missing_value": {
+		"a":,
+		"b": 1
+	},
+
+	"b": 1,
+	"c": "2", "d": 3
+}
+
+```
+
+
+=============================
+
+# Outputs
+
+## Output 1
+
+-----
+Indent style: Tab
+Line width: 80
+-----
+
+```json
+{
+	"missing_value": {
+		"a":,
+		"b": 1
+	},
+
+	"b": 1,
+	"c": "2",
+	"d": 3
+}
+```
+
+