cli: stop --jsx-* flags from switching the automatic JSX runtime to production

src/runtime/cli/Arguments.rs

@@ -1448,7 +1448,7 @@ pub fn parse(cmd: CommandTag, ctx: Context<'_>) -> crate::Result<api::TransformO
                 } else {
                     api::JsxRuntime::Automatic
                 },
-                development: false,
+                development: true,
                 side_effects: jsx_side_effects,
             });
         } else {
@@ -1464,7 +1464,7 @@ pub fn parse(cmd: CommandTag, ctx: Context<'_>) -> crate::Result<api::TransformO
                 } else {
                     prev.runtime
                 },
-                development: false,
+                development: prev.development,
                 side_effects: jsx_side_effects,
             });
         }

test/bundler/transpiler/jsx-cli-flags.test.ts

@@ -0,0 +1,73 @@
+import { describe, expect, test } from "bun:test";
+import { bunEnv, bunExe, tempDir } from "harness";
+
+// Passing a --jsx-* CLI flag must not flip the automatic runtime from
+// jsx-dev-runtime (development) to jsx-runtime (production). The flag only
+// overrides the field it names; dev/prod selection follows NODE_ENV exactly as
+// it does when no --jsx-* flag is present.
+describe.concurrent("jsx: --jsx-* CLI flags preserve development runtime", () => {
+  const shimFiles = {
+    "node_modules/react/package.json": JSON.stringify({
+      name: "react",
+      version: "1.0.0",
+      exports: {
+        ".": "./index.js",
+        "./jsx-runtime": "./prod.js",
+        "./jsx-dev-runtime": "./dev.js",
+      },
+    }),
+    "node_modules/react/index.js": "module.exports = {};",
+    "node_modules/react/prod.js":
+      "exports.jsx = () => ({ rt: 'PROD' }); exports.jsxs = exports.jsx; exports.Fragment = {};",
+    "node_modules/react/dev.js": "exports.jsxDEV = () => ({ rt: 'DEV' }); exports.Fragment = {};",
+    "a.jsx": "console.log(JSON.stringify(<div/>));",
+  };
+
+  type Case = [extraArgs: string[], nodeEnv: string | undefined, bunfig: string | undefined, expected: "DEV" | "PROD"];
+  const cases: Case[] = [
+    // Baselines (no --jsx-* flags): dev by default, prod only when NODE_ENV=production.
+    [[], undefined, undefined, "DEV"],
+    [[], "development", undefined, "DEV"],
+    [[], "production", undefined, "PROD"],
+    // Any --jsx-* flag must not change the dev/prod selection (no bunfig: fresh-construct branch).
+    [["--jsx-import-source=react"], undefined, undefined, "DEV"],
+    [["--jsx-import-source=react"], "development", undefined, "DEV"],
+    [["--jsx-import-source=react"], "production", undefined, "PROD"],
+    [["--jsx-fragment=Fragment"], undefined, undefined, "DEV"],
+    [["--jsx-fragment=Fragment"], "development", undefined, "DEV"],
+    [["--jsx-fragment=Fragment"], "production", undefined, "PROD"],
+    [["--jsx-factory=h"], undefined, undefined, "DEV"],
+    [["--jsx-runtime=automatic"], undefined, undefined, "DEV"],
+    [["--jsx-runtime=automatic"], "production", undefined, "PROD"],
+    // With a bunfig present, opts.jsx is already populated and CLI flags go through the
+    // merge-with-bunfig branch, which must preserve bunfig's `development` value.
+    [["--jsx-import-source=react"], undefined, "", "DEV"],
+    [["--jsx-import-source=react"], "production", "", "PROD"],
+    [["--jsx-fragment=Fragment"], undefined, "", "DEV"],
+    [["--jsx-import-source=react"], undefined, 'jsx = "react-jsx"\n', "PROD"],
+    [["--jsx-import-source=react"], undefined, 'jsx = "react-jsxDEV"\n', "DEV"],
+  ];
+
+  for (const [extraArgs, nodeEnv, bunfig, expected] of cases) {
+    const bunfigLabel = bunfig === undefined ? "no bunfig" : bunfig === "" ? "empty bunfig" : `bunfig ${bunfig.trim()}`;
+    const label = `bun ${extraArgs.join(" ") || "(no flags)"} NODE_ENV=${nodeEnv ?? "<unset>"} [${bunfigLabel}] -> ${expected}`;
+    test(label, async () => {
+      const files: Record<string, string> = { ...shimFiles };
+      if (bunfig !== undefined) files["bunfig.toml"] = bunfig;
+      using dir = tempDir("jsx-cli-dev", files);
+      const env: Record<string, string | undefined> = { ...bunEnv, NODE_ENV: nodeEnv };
+      if (nodeEnv === undefined) delete env.NODE_ENV;
+      await using proc = Bun.spawn({
+        cmd: [bunExe(), ...extraArgs, "a.jsx"],
+        env,
+        cwd: String(dir),
+        stdout: "pipe",
+        stderr: "pipe",
+      });
+      const [stdout, stderr, exitCode] = await Promise.all([proc.stdout.text(), proc.stderr.text(), proc.exited]);
+      expect(stderr).toBe("");
+      expect(stdout.trim()).toBe(JSON.stringify({ rt: expected }));
+      expect(exitCode).toBe(0);
+    });
+  }
+});