Separate if and else groups (fixes #616) (#1032)

src/printer.js

@@ -959,21 +959,20 @@ function genericPrintNoParens(path, options, print) {
       ]);
     case "IfStatement":
       const con = adjustClause(path.call(print, "consequent"), options);
-
-      parts = [
+      const opening = group(concat([
         "if (",
-        group(
-          concat([
-            indent(
-              options.tabWidth,
-              concat([softline, path.call(print, "test")])
-            ),
-            softline
-          ])
-        ),
+        group(concat([
+          indent(
+            options.tabWidth,
+            concat([softline, path.call(print, "test")])
+          ),
+          softline
+        ])),
         ")",
         con
-      ];
+      ]));
+
+      parts.push(opening);
 
       if (n.alternate) {
         const hasBraces = isCurlyBracket(con);
@@ -982,22 +981,19 @@ function genericPrintNoParens(path, options, print) {
         if (hasBraces && !isEmpty) {
           parts.push(" else");
         } else {
-          // We use `conditionalGroup` to suppress break propagation.
-          // This allows us to provide a hardline without forcing the
-          // entire `if` clause to break up.
-          parts.push(conditionalGroup([concat([hardline, "else"])]));
+          parts.push(hardline, "else");
         }
 
         parts.push(
-          adjustClause(
+          group(adjustClause(
             path.call(print, "alternate"),
             options,
             n.alternate.type === "IfStatement"
-          )
+          ))
         );
       }
 
-      return group(concat(parts));
+      return concat(parts);
     case "ForStatement": {
       const body = adjustClause(path.call(print, "body"), options);
 

tests/flow/refinements/__snapshots__/jsfmt.spec.js.snap

@@ -2506,8 +2506,7 @@ type Breakfast = Apple | Orange | Broccoli | Carrot;
 function bar(x: Breakfast) {
   if (x.kind === \\"Fruit\\") {
     (x.taste: \\"Good\\");
-  } else // error, Apple.taste = Bad
-    (x.raw: \\"No\\"); // error, Carrot.raw = Maybe
+  } else (x.raw: \\"No\\"); // error, Apple.taste = Bad // error, Carrot.raw = Maybe
 }
 
 function qux(x: Breakfast) {

tests/flow/type-destructors/__snapshots__/jsfmt.spec.js.snap

@@ -19,8 +19,7 @@ function foo(x: ?string): $NonMaybeType<?string> {
 function foo(x: ?string): $NonMaybeType<?string> {
   if (x != null) {
     return x;
-  } else
-    return 0; // this should be an error
+  } else return 0; // this should be an error
 }
 
 //(foo(): string); // should not be necessary to expose the error above

tests/if/__snapshots__/jsfmt.spec.js.snap

@@ -1,5 +1,89 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
+exports[`else.js 1`] = `
+"// Both functions below should be formatted exactly the same
+
+function f() {
+  if (position)
+    return {name: pair};
+  else
+    return {name: pair.substring(0, position), value: pair.substring(position + 1)};
+}
+
+function f() {
+  if (position)
+    return {name: pair};
+  else
+    return {
+      name: pair.substring(0, position),
+      value: pair.substring(position + 1)
+    };
+}
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+// Both functions below should be formatted exactly the same
+
+function f() {
+  if (position) return { name: pair };
+  else
+    return {
+      name: pair.substring(0, position),
+      value: pair.substring(position + 1)
+    };
+}
+
+function f() {
+  if (position) return { name: pair };
+  else
+    return {
+      name: pair.substring(0, position),
+      value: pair.substring(position + 1)
+    };
+}
+"
+`;
+
+exports[`else.js 2`] = `
+"// Both functions below should be formatted exactly the same
+
+function f() {
+  if (position)
+    return {name: pair};
+  else
+    return {name: pair.substring(0, position), value: pair.substring(position + 1)};
+}
+
+function f() {
+  if (position)
+    return {name: pair};
+  else
+    return {
+      name: pair.substring(0, position),
+      value: pair.substring(position + 1)
+    };
+}
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+// Both functions below should be formatted exactly the same
+
+function f() {
+  if (position) return { name: pair };
+  else
+    return {
+      name: pair.substring(0, position),
+      value: pair.substring(position + 1)
+    };
+}
+
+function f() {
+  if (position) return { name: pair };
+  else
+    return {
+      name: pair.substring(0, position),
+      value: pair.substring(position + 1)
+    };
+}
+"
+`;
+
 exports[`if_comments.js 1`] = `
 "async function f() {
   if (untrackedChoice === 0) /* Cancel */ {

tests/if/else.js

@@ -0,0 +1,18 @@
+// Both functions below should be formatted exactly the same
+
+function f() {
+  if (position)
+    return {name: pair};
+  else
+    return {name: pair.substring(0, position), value: pair.substring(position + 1)};
+}
+
+function f() {
+  if (position)
+    return {name: pair};
+  else
+    return {
+      name: pair.substring(0, position),
+      value: pair.substring(position + 1)
+    };
+}