Support Decimal Proposal (#8901)

changelog_unreleased/javascript/pr-8901.md

@@ -0,0 +1,16 @@
+#### Support Decimal Proposal ([#8901](https://github.com/prettier/prettier/pull/8901) by [@fisker](https://github.com/fisker))
+
+Support Stage-1 proposal [Decimal Proposal](https://github.com/tc39/proposal-decimal).
+
+<!-- prettier-ignore -->
+```js
+// Input
+0.3m;
+
+// Prettier stable
+SyntaxError: Identifier directly after number (1:4)
+> 1 | 0.3m;
+
+// Prettier master
+0.3m;
+```

src/language-js/clean.js

@@ -27,6 +27,10 @@ function clean(ast, newObj, parent) {
     newObj.value = newObj.value.toLowerCase();
   }
 
+  if (ast.type === "DecimalLiteral") {
+    newObj.value = Number(newObj.value);
+  }
+
   // We remove extra `;` and add them when needed
   if (ast.type === "EmptyStatement") {
     return null;

src/language-js/parser-babel.js

@@ -33,6 +33,7 @@ function babelOptions({ sourceType, extraPlugins = [] }) {
       "privateIn",
       ["moduleAttributes", { version: "may-2020" }],
       ["recordAndTuple", { syntaxType: "hash" }],
+      "decimal",
       ...extraPlugins,
     ],
     tokens: true,

src/language-js/printer-estree.js

@@ -1424,6 +1424,8 @@ function printPathNoParens(path, options, print, args) {
       return printRegex(n);
     case "NumericLiteral": // Babel 6 Literal split
       return printNumber(n.extra.raw);
+    case "DecimalLiteral":
+      return printNumber(n.value) + "m";
     case "BigIntLiteral":
       // babel: n.extra.raw, flow: n.bigint
       return (n.bigint || n.extra.raw).toLowerCase();

src/language-js/utils.js

@@ -146,6 +146,7 @@ function isLiteral(node) {
     node.type === "NullLiteral" ||
     node.type === "NumericLiteral" ||
     node.type === "BigIntLiteral" ||
+    node.type === "DecimalLiteral" ||
     node.type === "RegExpLiteral" ||
     node.type === "StringLiteral" ||
     node.type === "TemplateLiteral" ||
@@ -904,6 +905,7 @@ function isSimpleCallArgument(node, depth) {
   if (
     node.type === "Literal" ||
     node.type === "BigIntLiteral" ||
+    node.type === "DecimalLiteral" ||
     node.type === "BooleanLiteral" ||
     node.type === "NullLiteral" ||
     node.type === "NumericLiteral" ||

tests/js/babel-plugins/__snapshots__/jsfmt.spec.js.snap

@@ -356,6 +356,69 @@ console.log(Bork.staticFunction()); // > "babelIsCool"
 ================================================================================
 `;
 
+exports[`decimal.js format 1`] = `
+====================================options=====================================
+parsers: ["babel", "babel-ts", "babel-flow"]
+printWidth: 80
+                                                                                | printWidth
+=====================================input======================================
+// https://github.com/babel/babel/pull/11640
+
+100m;
+9223372036854775807m;
+0.m;
+3.1415926535897932m;
+100.000m;
+.1m;
+({ 0m: 0, .1m() {}, get 0.2m(){}, set 3m(_){}, async 4m() {}, *.5m() {} });
+1.m;
+100m;
+9223372036854775807m;
+100.m;
+
+// Invalid decimal
+2e9m;
+016432m;
+089m;
+
+// https://github.com/tc39/proposal-decimal
+.1m + .2m === .3m;
+2.00m;
+-0m;
+typeof 1m === "bigdecimal";
+typeof 1m === "decimal128";
+
+
+=====================================output=====================================
+// https://github.com/babel/babel/pull/11640
+
+100m;
+9223372036854775807m;
+0m;
+3.1415926535897932m;
+100.0m;
+0.1m;
+({ 0m: 0, 0.1m() {}, get 0.2m() {}, set 3m(_) {}, async 4m() {}, *0.5m() {} });
+1m;
+100m;
+9223372036854775807m;
+100m;
+
+// Invalid decimal
+2e9m;
+016432m;
+089m;
+
+// https://github.com/tc39/proposal-decimal
+0.1m + 0.2m === 0.3m;
+2.0m;
+-0m;
+typeof 1m === "bigdecimal";
+typeof 1m === "decimal128";
+
+================================================================================
+`;
+
 exports[`decorators.js format 1`] = `
 ====================================options=====================================
 parsers: ["babel", "babel-ts", "babel-flow"]

tests/js/babel-plugins/decimal.js

@@ -0,0 +1,26 @@
+// https://github.com/babel/babel/pull/11640
+
+100m;
+9223372036854775807m;
+0.m;
+3.1415926535897932m;
+100.000m;
+.1m;
+({ 0m: 0, .1m() {}, get 0.2m(){}, set 3m(_){}, async 4m() {}, *.5m() {} });
+1.m;
+100m;
+9223372036854775807m;
+100.m;
+
+// Invalid decimal
+2e9m;
+016432m;
+089m;
+
+// https://github.com/tc39/proposal-decimal
+.1m + .2m === .3m;
+2.00m;
+-0m;
+typeof 1m === "bigdecimal";
+typeof 1m === "decimal128";
+

tests/misc/errors/js/__snapshots__/jsfmt.spec.js.snap

@@ -93,6 +93,24 @@ exports[`snippet: #9 error test 1`] = `
     | ^"
 `;
 
+exports[`snippet: #10 error test 1`] = `
+"Invalid decimal (1:1)
+> 1 | 0b101011101m;
+    | ^"
+`;
+
+exports[`snippet: #11 error test 1`] = `
+"Invalid decimal (1:1)
+> 1 | 0x16432m;
+    | ^"
+`;
+
+exports[`snippet: #12 error test 1`] = `
+"Invalid decimal (1:1)
+> 1 | 0o16432m;
+    | ^"
+`;
+
 exports[`static-import-source-should-not-has-extra-token.js error test 1`] = `
 "Unexpected token (4:16)
   2 | // be parenthesized, that accidentally break #8016

tests/misc/errors/js/jsfmt.spec.js

@@ -39,6 +39,11 @@ run_spec(
       // Don't support `syntaxType: "bar"`
       "[| 1 |]",
       // "{| a: 1 |}", // babel didn't throw on this
+
+      // Invalid decimal
+      "0b101011101m;",
+      "0x16432m;",
+      "0o16432m;",
     ],
   },
   ["babel"]