From 3639c99b0f280dab3c13339b968680a7ffca615e Mon Sep 17 00:00:00 2001
From: Ed Page <eopage@gmail.com>
Date: Tue, 29 Mar 2022 06:54:54 -0500
Subject: [PATCH] fix!: Add 'std' feature

This will allow us to add no_std support without breaking compatibility
---
 .github/workflows/ci.yml        | 6 +++---
 .github/workflows/rust-next.yml | 4 ++--
 Cargo.toml                      | 5 ++++-
 src/lib.rs                      | 3 +++
 4 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index e296cc9..4160866 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -91,7 +91,7 @@ jobs:
     - name: All features
       run: cargo test --target ${{ matrix.target }} --workspace --all-features
     - name: No-default features
-      run: cargo test --target ${{ matrix.target }} --workspace --no-default-features
+      run: cargo test --target ${{ matrix.target }} --workspace --no-default-features --features std
   miri:
     name: Miri
     runs-on: ubuntu-latest
@@ -113,7 +113,7 @@ jobs:
     - name: All features
       run: cargo miri test --all-features
     - name: No-default features
-      run: cargo miri test --no-default-features
+      run: cargo miri test --no-default-features --features std
   msrv:
     name: "Check MSRV: 1.59.0"
     runs-on: ubuntu-latest
@@ -132,7 +132,7 @@ jobs:
     - name: All features
       run: cargo check --workspace --all-targets --all-features
     - name: No-default features
-      run: cargo check --workspace --all-targets --no-default-features
+      run: cargo check --workspace --all-targets --no-default-features --features std
   docs:
     name: Docs
     runs-on: ubuntu-latest
diff --git a/.github/workflows/rust-next.yml b/.github/workflows/rust-next.yml
index cdb11a9..8f895e6 100644
--- a/.github/workflows/rust-next.yml
+++ b/.github/workflows/rust-next.yml
@@ -29,7 +29,7 @@ jobs:
     - name: All features
       run: cargo test --workspace --all-features
     - name: No-default features
-      run: cargo test --workspace --no-default-features
+      run: cargo test --workspace --no-default-features --features std
   miri:
     name: Miri
     runs-on: ubuntu-latest
@@ -51,7 +51,7 @@ jobs:
     - name: All features
       run: cargo miri test --all-features
     - name: No-default features
-      run: cargo miri test --no-default-features
+      run: cargo miri test --no-default-features --features std
   rustfmt:
     name: rustfmt
     strategy:
diff --git a/Cargo.toml b/Cargo.toml
index da6ec9d..facf44f 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -34,7 +34,10 @@ pre-release-replacements = [
 ]
 
 [features]
-default = ["unsafe"]
+default = ["std", "unsafe"]
+
+## Allow use of `std`
+std = []
 
 ## O(1) clone support
 arc = []
diff --git a/src/lib.rs b/src/lib.rs
index 151597e..8b6edf3 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -22,6 +22,9 @@
 #![cfg_attr(feature = "document-features", doc = document_features::document_features!())]
 #![cfg_attr(feature = "safe", forbid(unsafe_code))]
 
+#[cfg(not(feature = "std"))]
+compile_error!("`std` feature is required; reserved for future `no_std` support");
+
 mod stack;
 mod string;
 mod string_cow;