Add support for V8 intrinsics via Babel

CHANGELOG.unreleased.md

@@ -836,6 +836,29 @@ type C = (number | string)["toString"];
 type D = (keyof T1)["foo"];
 ```
 
+#### JavaScript: Support formatting code with V8 intrinsics. ([#6496] by [@rreverser])
+
+<!-- prettier-ignore -->
+```js
+// Input
+function doSmth()     {
+            %DebugPrint
+        (
+                foo )
+  }
+
+// Prettier (stable)
+SyntaxError: Unexpected token (2:13)
+  1 | function doSmth()     {
+> 2 |             %DebugPrint
+    |             ^
+
+// Prettier (master)
+function doSmth() {
+  %DebugPrint(foo);
+}
+```
+
 [#5910]: https://github.com/prettier/prettier/pull/5910
 [#6033]: https://github.com/prettier/prettier/pull/6033
 [#6186]: https://github.com/prettier/prettier/pull/6186
@@ -863,6 +886,7 @@ type D = (keyof T1)["foo"];
 [#6467]: https://github.com/prettier/prettier/pull/6467
 [#6377]: https://github.com/prettier/prettier/pull/6377
 [#6604]: https://github.com/prettier/prettier/pull/6604
+[#6496]: https://github.com/prettier/prettier/pull/6496
 [@brainkim]: https://github.com/brainkim
 [@duailibe]: https://github.com/duailibe
 [@gavinjoyce]: https://github.com/gavinjoyce
@@ -872,3 +896,4 @@ type D = (keyof T1)["foo"];
 [@bakkot]: https://gibhub.com/bakkot
 [@thorn0]: https://github.com/thorn0
 [@dcyriller]: https://github.com/dcyriller
+[@rreverser]: https://github.com/RReverser

src/language-js/parser-babylon.js

@@ -37,7 +37,8 @@ function babelOptions(extraOptions, extraPlugins) {
         "bigInt",
         "throwExpressions",
         "logicalAssignment",
-        "classPrivateMethods"
+        "classPrivateMethods",
+        "v8intrinsic"
       ].concat(extraPlugins)
     },
     extraOptions

src/language-js/printer-estree.js

@@ -756,6 +756,8 @@ function printPathNoParens(path, options, print, args) {
         printTypeAnnotation(path, options, print)
       ]);
     }
+    case "V8IntrinsicIdentifier":
+      return concat(["%", n.name]);
     case "SpreadElement":
     case "SpreadElementPattern":
     case "RestProperty":

tests/v8_intrinsic/__snapshots__/jsfmt.spec.js.snap

@@ -0,0 +1,47 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`intrinsic_call.js 1`] = `
+====================================options=====================================
+parsers: ["babel"]
+printWidth: 80
+                                                                                | printWidth
+=====================================input======================================
+function doSmth()     {
+            %DebugPrint
+        (
+                foo )
+  }
+
+    function printFunc  (
+        f
+) {
+    if(%
+    IsAsmWasmCode(f))              console.log("asm.js");
+        if(
+
+        % IsWasmCode(
+        f))
+            console.log (
+                "wasm"
+            );
+
+    console.log
+    (%
+        GetFunctioName(f)
+        );
+}
+
+=====================================output=====================================
+function doSmth() {
+  %DebugPrint(foo);
+}
+
+function printFunc(f) {
+  if (%IsAsmWasmCode(f)) console.log("asm.js");
+  if (%IsWasmCode(f)) console.log("wasm");
+
+  console.log(%GetFunctioName(f));
+}
+
+================================================================================
+`;

tests/v8_intrinsic/intrinsic_call.js

@@ -0,0 +1,24 @@
+function doSmth()     {
+            %DebugPrint
+        (
+                foo )
+  }
+
+    function printFunc  (
+        f
+) {
+    if(%
+    IsAsmWasmCode(f))              console.log("asm.js");
+        if(
+
+        % IsWasmCode(
+        f))
+            console.log (
+                "wasm"
+            );
+
+    console.log
+    (%
+        GetFunctioName(f)
+        );
+}

tests/v8_intrinsic/jsfmt.spec.js

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