Setup JSX runtime even if the file doesn't contain JSX (#12479)

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

@@ -138,7 +138,6 @@ You can set \`throwIfNamespace: false\` to bypass this warning.`,
 
     Program: {
       enter(path, state) {
-        if (hasJSX(path)) {
         const { file } = state;
         let runtime = RUNTIME_DEFAULT;
 
@@ -268,7 +267,6 @@ You can set \`throwIfNamespace: false\` to bypass this warning.`,
         if (options.development) {
           path.traverse(injectMetaPropertiesVisitor, state);
         }
-        }
       },
 
       // TODO (Babel 8): Decide if this should be removed or brought back.
@@ -353,18 +351,6 @@ You can set \`throwIfNamespace: false\` to bypass this warning.`,
     return imports;
   }
 
-  function hasJSX(parentPath) {
-    let fileHasJSX = false;
-    parentPath.traverse({
-      "JSXElement|JSXFragment"(path) {
-        fileHasJSX = true;
-        path.stop();
-      },
-    });
-
-    return fileHasJSX;
-  }
-
   function getSource(source, importName) {
     switch (importName) {
       case "Fragment":

packages/babel-plugin-transform-react-jsx/test/fixtures/regression/issue-12478-automatic/input.js

@@ -0,0 +1 @@
+const foo = 2;

packages/babel-plugin-transform-react-jsx/test/fixtures/regression/issue-12478-automatic/options.json

@@ -0,0 +1,6 @@
+{
+  "plugins": [
+    ["transform-react-jsx", { "runtime": "automatic" }],
+    "./plugin.js"
+  ]
+}

packages/babel-plugin-transform-react-jsx/test/fixtures/regression/issue-12478-automatic/output.js

@@ -0,0 +1 @@
+const foo = /*#__PURE__*/undefined.jsx("p", {});

packages/babel-plugin-transform-react-jsx/test/fixtures/regression/issue-12478-automatic/plugin.js

@@ -0,0 +1,13 @@
+module.exports = ({ types: t }) => ({
+  visitor: {
+    NumericLiteral(path) {
+      path.replaceWith(
+        t.jsxElement(
+          t.jsxOpeningElement(t.jsxIdentifier("p"), []),
+          t.jsxClosingElement(t.jsxIdentifier("p")),
+          []
+        )
+      );
+    }
+  }
+});

packages/babel-plugin-transform-react-jsx/test/fixtures/regression/issue-12478-classic/input.js

@@ -0,0 +1 @@
+const foo = 2;

packages/babel-plugin-transform-react-jsx/test/fixtures/regression/issue-12478-classic/options.json

@@ -0,0 +1,6 @@
+{
+  "plugins": [
+    ["transform-react-jsx", { "runtime": "classic" }],
+    "./plugin.js"
+  ]
+}

packages/babel-plugin-transform-react-jsx/test/fixtures/regression/issue-12478-classic/output.js

@@ -0,0 +1 @@
+const foo = /*#__PURE__*/React.createElement("p", null);

packages/babel-plugin-transform-react-jsx/test/fixtures/regression/issue-12478-classic/plugin.js

@@ -0,0 +1,13 @@
+module.exports = ({ types: t }) => ({
+  visitor: {
+    NumericLiteral(path) {
+      path.replaceWith(
+        t.jsxElement(
+          t.jsxOpeningElement(t.jsxIdentifier("p"), []),
+          t.jsxClosingElement(t.jsxIdentifier("p")),
+          []
+        )
+      );
+    }
+  }
+});