From 356869dfb16a112c68def3718fc707654217df0c Mon Sep 17 00:00:00 2001
From: Ravi Chamarthy <ravi@ciroos.ai>
Date: Thu, 3 Sep 2026 18:33:28 -0700
Subject: [PATCH] fix: `vec!` macro resolution via alloc::vec self-import

`use alloc::vec::{self, Vec};` relies on the `self` import also
bringing the `vec!` macro into scope alongside the `vec` module.
On some rustc versions this only resolves the module (type
namespace), so unqualified `vec![...]` calls in this file fail
with "cannot find macro `vec` in this scope".

Import `Drain` by name instead of the `vec` module, and fully
qualify the two `vec!` invocations (`alloc::vec!` / `$crate::alloc::vec!`)
so macro resolution no longer depends on the `self`-import quirk.

Signed-off-by: Ravi Chamarthy <ravi@ciroos.ai>
---
 .github/workflows/rust.yml |  2 +-
 Cargo.toml                 |  4 ++++
 src/tinyvec.rs             |  6 +++---
 tests/no_std_macro.rs      | 11 +++++++++++
 4 files changed, 19 insertions(+), 4 deletions(-)
 create mode 100644 tests/no_std_macro.rs

diff --git a/.github/workflows/rust.yml b/.github/workflows/rust.yml
index 44af3b1..bc1acaa 100644
--- a/.github/workflows/rust.yml
+++ b/.github/workflows/rust.yml
@@ -34,7 +34,7 @@ jobs:
     - name: Check no_std with alloc
       if: matrix.rust != '1.60.0'
       run: |
-        cargo check --no-default-features --features=alloc,grab_spare_slice,latest_stable_rust
+        cargo check --tests --no-default-features --features=alloc,grab_spare_slice,latest_stable_rust
     - name: Test non nightly
       if: matrix.rust != '1.60.0' && matrix.rust != 'nightly'
       run: |
diff --git a/Cargo.toml b/Cargo.toml
index 28e8d68..651084f 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -113,6 +113,10 @@ debugger_test_parser = "0.1"
 name = "tinyvec"
 required-features = ["alloc", "std"]
 
+[[test]]
+name = "no_std_macro"
+required-features = ["alloc"]
+
 [[bench]]
 name = "macros"
 harness = false
diff --git a/src/tinyvec.rs b/src/tinyvec.rs
index 48ef36b..0781fc7 100644
--- a/src/tinyvec.rs
+++ b/src/tinyvec.rs
@@ -1,6 +1,6 @@
 use super::*;
 
-use alloc::vec::{self, Vec};
+use alloc::vec::{Drain, Vec};
 use core::convert::TryFrom;
 use tinyvec_macros::impl_mirrored;
 
@@ -46,7 +46,7 @@ macro_rules! tiny_vec {
           f($crate::array_vec!($array_type => $($elem),*))
         }
         $crate::TinyVecConstructor::Heap(f) => {
-          f(vec![$($elem),*])
+          f($crate::alloc::vec![$($elem),*])
         }
       }
     }
@@ -1308,7 +1308,7 @@ pub enum TinyVecDrain<'p, A: Array> {
   #[allow(missing_docs)]
   Inline(ArrayVecDrain<'p, A::Item>),
   #[allow(missing_docs)]
-  Heap(vec::Drain<'p, A::Item>),
+  Heap(Drain<'p, A::Item>),
 }
 
 impl<'p, A: Array> Iterator for TinyVecDrain<'p, A> {
diff --git a/tests/no_std_macro.rs b/tests/no_std_macro.rs
new file mode 100644
index 0000000..9478e6e
--- /dev/null
+++ b/tests/no_std_macro.rs
@@ -0,0 +1,11 @@
+//! Regression test for the `tiny_vec!` macro's heap arm expanding cleanly
+//! in a downstream `#![no_std]` crate, where there is no `std` prelude
+//! `vec!` to mask a macro-hygiene resolution bug.
+#![no_std]
+
+use tinyvec::{tiny_vec, TinyVec};
+
+#[allow(dead_code)]
+fn expands_to_heap() -> TinyVec<[u8; 1]> {
+  tiny_vec!([u8; 1] => 1, 2)
+}