title: Unable to build the library using cargo lipo --release
body: <h2>Unable to build the library using cargo lipo --release</h2>
  <p>I am trying to make a cross-platform library using rust for ios target. I am following this article <a href="https://mozilla.github.io/firefox-browser-architecture/experiments/2017-09-06-rust-on-ios.html" rel="nofollow noreferrer">(Building and Deploying a Rust library on iOS)</a>.
  *Note: I followed the same steps and my project structure also looks the same *</p>
  <p>After completing the code and project setup the last step is to build the library. When I try to build the library using <code>cargo lipo --release</code>. It throws this error:</p>
  <p><code>[ERROR cargo_lipo] No library target found for &quot;my-project-name&quot;</code></p>
  <p>Also, note that I am only able to <strong>install support for two platforms</strong>. (<code>aarch64-apple-ios</code> and <code>x86_64-apple-darwin</code>). I think the reason is that they have <a href="https://blog.rust-lang.org/2020/01/03/reducing-support-for-32-bit-apple-targets.html" rel="nofollow noreferrer">dropped the support for 32-bit architectures</a>.</p>
  <p>So, when I run
  <code>rustup target add aarch64-apple-ios armv7-apple-ios armv7s-apple-ios x86_64-apple-ios i386-apple-ios</code>.</p>
  <p>It throws error: <code>error: component 'rust-std' for target 'armv7-apple-ios' is unavailable for download for channel stable</code></p>
  <hr />
  <p>Cargo.toml</p>
  <pre><code>[package]
  name = &quot;rustylib&quot;
  version = &quot;0.1.0&quot;
  edition = &quot;2018&quot;
  crate-type = [&quot;staticlib&quot;, &quot;cdylib&quot;]
  </code></pre>
  <p>rustylib.rs</p>
  <pre><code>#include &lt;stdarg.h&gt;
  #include &lt;stdbool.h&gt;
  #include &lt;stdint.h&gt;
  #include &lt;stdlib.h&gt;
  
  char *hello(const char *to);
  
  void hello_release(char *s);
  </code></pre>
  <p>The rest of the project structure is the usual rust code.</p>
  <h3>The output of <code>rustup</code> show</h3>
  <p>Default host: x86_64-apple-darwin
  rustup home:  /Users/my-username/.rustup</p>
  <h2>installed toolchains</h2>
  <p>stable-x86_64-apple-darwin</p>
  <p>nightly-x86_64-apple-darwin (default)</p>
  <h2>installed targets for active toolchain</h2>
  <p>aarch64-apple-ios</p>
  <p>x86_64-apple-darwin</p>
  <h2>active toolchain</h2>
  <p>nightly-x86_64-apple-darwin (default)</p>
  <p>rustc 1.52.0-nightly (acca81892 2021-03-13)</p>
  <h2>OS &amp; Rust</h2>
  <p>Rust: rustc 1.50.0 (cb75ad5db 2021-02-10)</p>
  <p>OS: macOS Bug Sur (11.2.3)</p>
  <p>Xcode &amp; Command line tools: 12.4</p>