Ensure no-std works via CI

.github/workflows/ci.yml

@@ -1,29 +1,63 @@
 on: pull_request
 
-name: Continuous integration
+name: Continuous Integration
+
+env:
+  RUSTFLAGS: -D warnings
 
 jobs:
   ci:
-    runs-on: ${{ matrix.os }}
+    name: ${{ matrix.target.name }} [${{ matrix.rust_version }}]
+    runs-on: ${{ matrix.target.os }}
     strategy:
+      fail-fast: false
       matrix:
-        rust:
-          - stable
-        os: [ubuntu-latest, windows-latest]
+        rust_version: ["stable", "1.62.1"]
+        target:
+          - name: Linux
+            os: ubuntu-latest
+            extra_flags: --all-features
+            run_tests: true
+
+          - name: Linux (no-std)
+            os: ubuntu-latest
+            extra_flags: --no-default-features
+            run_tests: true
+
+          - name: Windows
+            os: windows-latest
+            extra_flags: --all-features
+            run_tests: true
+
+          - name: Windows (no-std)
+            os: windows-latest
+            extra_flags: --no-default-features
+            run_tests: true
+
+          - name: Bare Metal (no-std)
+            os: ubuntu-latest
+            extra_flags: --no-default-features
+            run_tests: false
+            env:
+              TARGET: thumbv7em-none-eabihf
+
 
     steps:
       - uses: actions/checkout@v3
 
       - uses: dtolnay/rust-toolchain@master
         with:
-          toolchain: ${{ matrix.rust }}
-          components: rustfmt, clippy
+          targets: ${{ matrix.target.env.TARGET || '' }}
+          toolchain: ${{ matrix.rust_version }}
+          components: clippy, rustfmt
 
       - run: cargo fmt --check --all
-      - run: cargo clippy -- -D warnings
-      - run: cargo build --all-features
-      - run: cargo test
-      - run: cargo test --all-features
-      - run: cargo run --example 256_colors
-      - run: cargo run --example hyperlink
-      - run: cargo run --example title
+      - run: cargo clippy ${{ matrix.target.extra_flags }}
+      - run: cargo build ${{ matrix.target.extra_flags }}
+
+      - if: matrix.target.run_tests
+        run: |
+          cargo test ${{ matrix.target.extra_flags }}
+          cargo run ${{ matrix.target.extra_flags }} --example 256_colors
+          cargo run ${{ matrix.target.extra_flags }} --example hyperlink
+          cargo run ${{ matrix.target.extra_flags }} --example title

.gitignore

@@ -1,5 +1,4 @@
 target
-Cargo.lock
 
 # JetBrains' IDE items
 .idea/*

Cargo.toml

@@ -17,6 +17,8 @@ repository = "https://github.com/nushell/nu-ansi-term"
 doctest = true
 
 [features]
+default = ["std"]
+std = []
 derive_serde_style = ["serde"]
 gnu_legacy = []
 

examples/256_colors.rs

@@ -9,7 +9,7 @@ use nu_ansi_term::Color;
 // - 232 to 255 are shades of grey.
 
 fn main() {
-    #[cfg(windows)]
+    #[cfg(all(windows, feature = "std"))]
     nu_ansi_term::enable_ansi_support().unwrap();
 
     // First two lines

examples/basic_colors.rs

@@ -3,7 +3,7 @@ use nu_ansi_term::{Color::*, Style};
 // This example prints out the 16 basic colors.
 
 fn main() {
-    #[cfg(windows)]
+    #[cfg(all(windows, feature = "std"))]
     nu_ansi_term::enable_ansi_support().unwrap();
 
     let normal = Style::default();

examples/gradient_colors.rs

@@ -1,7 +1,7 @@
 use nu_ansi_term::{build_all_gradient_text, Color, Gradient, Rgb, TargetGround};
 
 fn main() {
-    #[cfg(windows)]
+    #[cfg(all(windows, feature = "std"))]
     nu_ansi_term::enable_ansi_support().unwrap();
 
     let text = "lorem ipsum quia dolor sit amet, consectetur, adipisci velit";

examples/hyperlink.rs

@@ -3,7 +3,7 @@ mod may_sleep;
 use may_sleep::{parse_cmd_args, sleep};
 
 fn main() {
-    #[cfg(windows)]
+    #[cfg(all(windows, feature = "std"))]
     nu_ansi_term::enable_ansi_support().unwrap();
 
     let sleep_ms = parse_cmd_args();

examples/rgb_colors.rs

@@ -8,7 +8,7 @@ const WIDTH: i32 = 80;
 const HEIGHT: i32 = 24;
 
 fn main() {
-    #[cfg(windows)]
+    #[cfg(all(windows, feature = "std"))]
     nu_ansi_term::enable_ansi_support().unwrap();
 
     for row in 0..HEIGHT {

examples/title.rs

@@ -3,7 +3,7 @@ mod may_sleep;
 use may_sleep::{parse_cmd_args, sleep};
 
 fn main() {
-    #[cfg(windows)]
+    #[cfg(all(windows, feature = "std"))]
     nu_ansi_term::enable_ansi_support().unwrap();
 
     let sleep_ms = parse_cmd_args();

src/ansi.rs

@@ -1,7 +1,7 @@
 #![allow(missing_docs)]
 use crate::style::{Color, Style};
 use crate::write::AnyWrite;
-use std::fmt;
+use core::fmt;
 
 impl Style {
     /// Write any bytes that go *before* a piece of text to the given writer.
@@ -400,6 +400,7 @@ impl fmt::Display for Suffix {
 }
 
 #[cfg(test)]
+#[allow(unused)]
 macro_rules! test {
     ($name: ident: $style: expr; $input: expr => $result: expr) => {
         #[test]
@@ -414,8 +415,9 @@ macro_rules! test {
 }
 
 #[cfg(test)]
-#[cfg(not(feature = "gnu_legacy"))]
+#[cfg(all(not(feature = "gnu_legacy"), feature = "std"))]
 mod test {
+
     use crate::style::Color::*;
     use crate::style::Style;
     use crate::Color;

src/debug.rs

@@ -1,5 +1,5 @@
 use crate::style::Style;
-use std::fmt;
+use core::fmt;
 
 /// Styles have a special `Debug` implementation that only shows the fields that
 /// are set. Fields that haven’t been touched aren’t included in the output.