fix(linter/curly): fix multi-or-nest and consistent conflict (#18660)

Skip else-if statements when running the curly rule, as they are already handled as part of the parent if-else chain. This prevents duplicate diagnostics and fixes the conflict where multi-or-nest would suggest removing braces while consistent would require them.

fixes #18566

Author: camc314

crates/oxc_linter/src/rules/eslint/curly.rs

@@ -278,7 +278,9 @@ impl Rule for Curly {
 
     fn run<'a>(&self, node: &AstNode<'a>, ctx: &LintContext<'a>) {
         match node.kind() {
-            AstKind::IfStatement(stmt) => self.run_for_if_statement(stmt, ctx),
+            AstKind::IfStatement(stmt) if !is_else_if(node, stmt, ctx) => {
+                self.run_for_if_statement(stmt, ctx);
+            }
             AstKind::ForStatement(stmt) => self.run_for_loop("for", &stmt.body, ctx),
             AstKind::ForInStatement(stmt) => self.run_for_loop("for-in", &stmt.body, ctx),
             AstKind::ForOfStatement(stmt) => self.run_for_loop("for-of", &stmt.body, ctx),
@@ -360,6 +362,15 @@ fn get_if_else_keyword(is_else: bool) -> &'static str {
     if is_else { "else" } else { "if" }
 }
 
+fn is_else_if(node: &AstNode, stmt: &IfStatement, ctx: &LintContext) -> bool {
+    if let AstKind::IfStatement(parent_if) = ctx.nodes().parent_kind(node.id())
+        && parent_if.alternate.as_ref().is_some_and(|alt| alt.span() == stmt.span)
+    {
+        return true;
+    }
+    false
+}
+
 fn has_braces(body: &Statement) -> bool {
     matches!(body, Statement::BlockStatement(_))
 }
@@ -885,6 +896,17 @@ fn test() {
             "if (a) { if (b) foo(); } else { bar(); }",
             Some(serde_json::json!(["multi-or-nest", "consistent"])),
         ),
+        (
+            "if (dividerPosition) {
+              if (condition1 && condition2) {
+                closePos = state.pos;
+                const y = closePos;
+              }
+            } else if (condition3 && condition4) {
+              dividerPosition = state.pos;
+            }",
+            Some(serde_json::json!(["multi-or-nest", "consistent"])),
+        ),
         ("if (a) { if (b) { foo(); bar(); } } else baz();", Some(serde_json::json!(["multi"]))),
         (
             "if (a) foo(); else if (b) { if (c) bar(); } else baz();",

crates/oxc_linter/src/snapshots/eslint_curly.snap

@@ -30,13 +30,6 @@ source: crates/oxc_linter/src/tester.rs
    ╰────
   help: Replace `baz()` with `{baz()}`.
 
-  ⚠ eslint(curly): Expected { after 'if' condition.
-   ╭─[curly.tsx:1:34]
- 1 │ if (foo) { bar() } else if (faa) baz()
-   ·                                  ─────
-   ╰────
-  help: Replace `baz()` with `{baz()}`.
-
   ⚠ eslint(curly): Expected { after 'while' condition.
    ╭─[curly.tsx:1:13]
  1 │ while (foo) bar()
@@ -161,13 +154,6 @@ source: crates/oxc_linter/src/tester.rs
    ╰────
   help: Replace `{ quuux(); }` with ` quuux(); `.
 
-  ⚠ eslint(curly): Unexpected { after 'if' condition.
-   ╭─[curly.tsx:1:41]
- 1 │ if (foo) if (bar) baz(); else if (quux) { quuux(); }
-   ·                                         ────────────
-   ╰────
-  help: Replace `{ quuux(); }` with ` quuux(); `.
-
   ⚠ eslint(curly): Unexpected { after 'while' condition.
    ╭─[curly.tsx:1:13]
  1 │ while (foo) { bar() }
@@ -211,28 +197,6 @@ source: crates/oxc_linter/src/tester.rs
   8 │ │                       console.log(2)
   9 │ │                   else
  10 │ │                       console.log(3)
- 11 │ ╰─▶             }
-    ╰────
-  help: Replace `{
-        			    if (2)
-        			        console.log(2)
-        			    else
-        			        console.log(3)
-        			}` with `
-        			    if (2)
-        			        console.log(2)
-        			    else
-        			        console.log(3)
-        			`.
-
-  ⚠ eslint(curly): Unexpected { after 'else'.
-    ╭─[curly.tsx:6:11]
-  5 │                     console.log(1)
-  6 │ ╭─▶             } else {
-  7 │ │                   if (2)
-  8 │ │                       console.log(2)
-  9 │ │                   else
- 10 │ │                       console.log(3)
  11 │ ╰─▶             }
     ╰────
   help: Replace `{
@@ -560,13 +524,6 @@ source: crates/oxc_linter/src/tester.rs
    ╰────
   help: Replace `faa();` with `{faa();}`.
 
-  ⚠ eslint(curly): Expected { after 'if' condition.
-   ╭─[curly.tsx:1:33]
- 1 │ if (true) foo(); else if (true) faa(); else { bar(); baz(); }
-   ·                                 ──────
-   ╰────
-  help: Replace `faa();` with `{faa();}`.
-
   ⚠ eslint(curly): Expected { after 'if' condition.
    ╭─[curly.tsx:1:21]
  1 │ if (true) if (true) foo(); else { bar(); baz(); }
@@ -749,22 +706,6 @@ source: crates/oxc_linter/src/tester.rs
  2 │ ╭─▶             else if (bar) {
  3 │ │               doSomethingElse()
  4 │ │               ;
- 5 │ ╰─▶             }
-   ╰────
-  help: Replace `{
-        			doSomethingElse()
-        			;
-        			}` with `
-        			doSomethingElse()
-        			;
-        			`.
-
-  ⚠ eslint(curly): Unexpected { after 'if' condition.
-   ╭─[curly.tsx:2:18]
- 1 │     if (foo) doSomething();
- 2 │ ╭─▶             else if (bar) {
- 3 │ │               doSomethingElse()
- 4 │ │               ;
  5 │ ╰─▶             }
    ╰────
   help: Replace `{
@@ -1016,13 +957,6 @@ source: crates/oxc_linter/src/tester.rs
    ╰────
   help: Replace `{bar();}` with `bar();`.
 
-  ⚠ eslint(curly): Unexpected { after 'if' condition.
-   ╭─[curly.tsx:1:51]
- 1 │ if(a) { if (b) foo(); } if (c) bar(); else if(foo){bar();}
-   ·                                                   ────────
-   ╰────
-  help: Replace `{bar();}` with `bar();`.
-
   ⚠ eslint(curly): Expected { after 'if' condition.
    ╭─[curly.tsx:1:11]
  1 │ ╭─▶ if (true) [1, 2, 3]