Allow multiple __self/__source props with classic JSX runtime (#12475)

packages/babel-helper-builder-react-jsx-experimental/src/index.js

@@ -862,7 +862,6 @@ You can set \`throwIfNamespace: false\` to bypass this warning.`,
 
     let props = [];
     const objs = [];
-    const found = Object.create(null);
 
     for (const attr of attribs) {
       const name =
@@ -870,10 +869,8 @@ You can set \`throwIfNamespace: false\` to bypass this warning.`,
         t.isJSXIdentifier(attr.name) &&
         attr.name.name;
 
-      if (name === "__source" || name === "__self") {
+      if (!options.development && (name === "__source" || name === "__self")) {
-        if (found[name]) throw sourceSelfError(path, name);
+        continue;
-        found[name] = true;
-        if (!options.development) continue;
       }
 
       if (useSpread || !t.isJSXSpreadAttribute(attr)) {

packages/babel-preset-react/test/fixtures/regression/runtime-classic-allow-multiple-source-self/input.mjs

@@ -0,0 +1 @@
+<div/>

packages/babel-preset-react/test/fixtures/regression/runtime-classic-allow-multiple-source-self/my-preset.js

@@ -0,0 +1,3 @@
+module.exports = () => ({
+  presets: [["@babel/preset-react", { development: true }]],
+});

packages/babel-preset-react/test/fixtures/regression/runtime-classic-allow-multiple-source-self/options.json

@@ -0,0 +1,4 @@
+{
+  "presets": [["@babel/preset-react", { "development": true }], "./my-preset"],
+  "os": ["linux", "darwin"]
+}

packages/babel-preset-react/test/fixtures/regression/runtime-classic-allow-multiple-source-self/output.mjs

@@ -0,0 +1,18 @@
+var _jsxFileName = "<CWD>/packages/babel-preset-react/test/fixtures/regression/runtime-classic-allow-multiple-source-self/input.mjs",
+    _jsxFileName2 = "<CWD>/packages/babel-preset-react/test/fixtures/regression/runtime-classic-allow-multiple-source-self/input.mjs";
+
+/*#__PURE__*/
+React.createElement("div", {
+  __self: this,
+  __source: {
+    fileName: _jsxFileName,
+    lineNumber: 1,
+    columnNumber: 1
+  },
+  __self: this,
+  __source: {
+    fileName: _jsxFileName2,
+    lineNumber: 1,
+    columnNumber: 1
+  }
+});