Put loop bodies on the same line when possible (#1498)

src/printer.js

@@ -1130,12 +1130,12 @@ function genericPrintNoParens(path, options, print, args) {
         options
       );
     case "WithStatement":
-      return concat([
+      return group(concat([
         "with (",
         path.call(print, "object"),
         ")",
         adjustClause(n.body, path.call(print, "body"))
-      ]);
+      ]));
     case "IfStatement":
       const con = adjustClause(n.consequent, path.call(print, "consequent"));
       const opening = group(
@@ -1187,35 +1187,37 @@ function genericPrintNoParens(path, options, print, args) {
       const printedComments = dangling ? concat([dangling, softline]) : "";
 
       if (!n.init && !n.test && !n.update) {
-        return concat([printedComments, "for (;;)", body]);
+        return concat([printedComments, group(concat(["for (;;)", body]))]);
       }
 
       return concat([
         printedComments,
-        "for (",
-        group(
-          concat([
-            indent(
-              concat([
-                softline,
-                path.call(print, "init"),
-                ";",
-                line,
-                path.call(print, "test"),
-                ";",
-                line,
-                path.call(print, "update")
-              ])
-            ),
-            softline
-          ])
-        ),
-        ")",
-        body
+        group(concat([
+          "for (",
+          group(
+            concat([
+              indent(
+                concat([
+                  softline,
+                  path.call(print, "init"),
+                  ";",
+                  line,
+                  path.call(print, "test"),
+                  ";",
+                  line,
+                  path.call(print, "update")
+                ])
+              ),
+              softline
+            ])
+          ),
+          ")",
+          body
+        ]))
       ]);
     }
     case "WhileStatement":
-      return concat([
+      return group(concat([
         "while (",
         group(
           concat([
@@ -1225,17 +1227,17 @@ function genericPrintNoParens(path, options, print, args) {
         ),
         ")",
         adjustClause(n.body, path.call(print, "body"))
-      ]);
+      ]));
     case "ForInStatement":
       // Note: esprima can't actually parse "for each (".
-      return concat([
+      return group(concat([
         n.each ? "for each (" : "for (",
         path.call(print, "left"),
         " in ",
         path.call(print, "right"),
         ")",
         adjustClause(n.body, path.call(print, "body"))
-      ]);
+      ]));
 
     case "ForOfStatement":
     case "ForAwaitStatement":
@@ -1244,7 +1246,7 @@ function genericPrintNoParens(path, options, print, args) {
       // https://github.com/estree/estree/pull/138
       const isAwait = n.type === "ForAwaitStatement" || n.await;
 
-      return concat([
+      return group(concat([
         "for",
         isAwait ? " await" : "",
         " (",
@@ -1253,11 +1255,11 @@ function genericPrintNoParens(path, options, print, args) {
         path.call(print, "right"),
         ")",
         adjustClause(n.body, path.call(print, "body"))
-      ]);
+      ]));
 
     case "DoWhileStatement":
       var clause = adjustClause(n.body, path.call(print, "body"));
-      var doBody = concat(["do", clause]);
+      var doBody = group(concat(["do", clause]));
       var parts = [doBody];
 
       if (n.body.type === "BlockStatement") {

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

@@ -70,12 +70,18 @@ for (x of y);
 exports[`for.js 1`] = `
 for (;;) {}
 for (var i = 0; i < 10; ++i) {}
+
+for (;;) 0;
+for (var i = 0; i < 10; ++i) 0;
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 for (;;) {
 }
 for (var i = 0; i < 10; ++i) {
 }
 
+for (;;) 0;
+for (var i = 0; i < 10; ++i) 0;
+
 `;
 
 exports[`in.js 1`] = `
@@ -90,6 +96,7 @@ function* g() {
 async function f() {
   for (await (a in b); ; );
 }
+for (a in b) 0;
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 for ((x in a); ; ) {
 }
@@ -104,14 +111,14 @@ function* g() {
 async function f() {
   for (await (a in b); ; );
 }
+for (a in b) 0;
 
 `;
 
 exports[`var.js 1`] = `
 for (a in b) var c = {}; [];
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-for (a in b)
-  var c = {};
+for (a in b) var c = {};
 [];
 
 `;

tests/for/for.js

@@ -1,2 +1,5 @@
 for (;;) {}
 for (var i = 0; i < 10; ++i) {}
+
+for (;;) 0;
+for (var i = 0; i < 10; ++i) 0;

tests/for/in.js

@@ -9,3 +9,4 @@ function* g() {
 async function f() {
   for (await (a in b); ; );
 }
+for (a in b) 0;

tests/no-semi/__snapshots__/jsfmt.spec.js.snap

@@ -359,12 +359,10 @@ if (true) {
 
 // check statement clauses
 
-do
-  break;
+do break;
 while (false);
 if (true)
-  do
-    break;
+  do break;
   while (false);
 
 if (true) 1;
@@ -401,8 +399,7 @@ x;
 x;
 ++(a || b).c;
 
-while (false)
-  (function() {})();
+while (false) (function() {})();
 
 aReallyLongLine012345678901234567890123456789012345678901234567890123456789 *
   (b + c);
@@ -687,12 +684,10 @@ if (true) {
 
 // check statement clauses
 
-do
-  break
+do break
 while (false)
 if (true)
-  do
-    break
+  do break
   while (false)
 
 if (true) 1
@@ -729,8 +724,7 @@ x
 x
 ++(a || b).c
 
-while (false)
-  (function() {})()
+while (false) (function() {})()
 
 aReallyLongLine012345678901234567890123456789012345678901234567890123456789 *
   (b + c)
@@ -1015,12 +1009,10 @@ if (true) {
 
 // check statement clauses
 
-do
-  break
+do break
 while (false)
 if (true)
-  do
-    break
+  do break
   while (false)
 
 if (true) 1
@@ -1057,8 +1049,7 @@ x
 x
 ++(a || b).c
 
-while (false)
-  (function() {})()
+while (false) (function() {})()
 
 aReallyLongLine012345678901234567890123456789012345678901234567890123456789 *
   (b + c)

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

@@ -5,6 +5,11 @@ if (someVeryLongStringA && someVeryLongStringB && someVeryLongStringC && someVer
 while (someVeryLongStringA && someVeryLongStringB && someVeryLongStringC && someVeryLongStringD) {}
 do {}
 while (someVeryLongStringA && someVeryLongStringB && someVeryLongStringC && someVeryLongStringD);
+
+while (0) 1;
+
+do 1;
+while (0);
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 if (
   someVeryLongStringA &&
@@ -28,4 +33,9 @@ do {
   someVeryLongStringD
 );
 
+while (0) 1;
+
+do 1;
+while (0);
+
 `;

tests/while/indent.js

@@ -2,3 +2,8 @@ if (someVeryLongStringA && someVeryLongStringB && someVeryLongStringC && someVer
 while (someVeryLongStringA && someVeryLongStringB && someVeryLongStringC && someVeryLongStringD) {}
 do {}
 while (someVeryLongStringA && someVeryLongStringB && someVeryLongStringC && someVeryLongStringD);
+
+while (0) 1;
+
+do 1;
+while (0);

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

@@ -0,0 +1,13 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`indent.js 1`] = `
+with (0) {}
+
+with (0) 1;
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+with (0) {
+}
+
+with (0) 1;
+
+`;

tests/with/indent.js

@@ -0,0 +1,3 @@
+with (0) {}
+
+with (0) 1;

tests/with/jsfmt.spec.js

@@ -0,0 +1 @@
+run_spec(__dirname, null, ["typescript"]);