Add allocator_api example

Author: newAM

.github/workflows/ci.yml

@@ -24,7 +24,7 @@ jobs:
         with:
           targets: ${{ matrix.target }}
           toolchain: ${{ matrix.toolchain }}
-      - run: cargo check --target=${{ matrix.target }} --examples
+      - run: cargo check --target=${{ matrix.target }} --example global_alloc
       - if: ${{ matrix.toolchain == 'nightly' }}
         run: cargo check --target=${{ matrix.target }} --examples --all-features
 

examples/allocator_api.rs

@@ -0,0 +1,35 @@
+#![feature(allocator_api)]
+#![no_std]
+#![no_main]
+
+extern crate alloc;
+
+use alloc::vec::Vec;
+use core::mem::MaybeUninit;
+use core::panic::PanicInfo;
+use cortex_m_rt::entry;
+use embedded_alloc::Heap;
+
+// This is not used, but as of 2023-10-29 allocator_api cannot be used without
+// a global heap
+#[global_allocator]
+static HEAP: Heap = Heap::empty();
+
+#[entry]
+fn main() -> ! {
+    const HEAP_SIZE: usize = 16;
+    static mut HEAP_MEM: [MaybeUninit<u8>; HEAP_SIZE] = [MaybeUninit::uninit(); HEAP_SIZE];
+    let heap: Heap = Heap::empty();
+    unsafe { heap.init(HEAP_MEM.as_ptr() as usize, HEAP_SIZE) }
+
+    let mut xs = Vec::new_in(heap);
+    xs.push(1);
+
+    #[allow(clippy::empty_loop)]
+    loop { /* .. */ }
+}
+
+#[panic_handler]
+fn panic(_: &PanicInfo) -> ! {
+    loop {}
+}