Hide C-string tests from old toolchain versions

Author: dtolnay

.github/workflows/ci.yml

@@ -24,7 +24,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        rust: [nightly, beta, stable, 1.76.0, 1.60.0]
+        rust: [nightly, beta, stable, 1.77.0, 1.76.0, 1.60.0]
     timeout-minutes: 45
     steps:
       - uses: actions/checkout@v5

Cargo.toml

@@ -6,6 +6,7 @@ categories = ["rust-patterns", "text-processing", "no-std", "no-std::no-alloc"]
 description = "Indented document literals"
 documentation = "https://docs.rs/indoc"
 edition = "2021"
+exclude = ["build.rs"]
 keywords = ["heredoc", "nowdoc", "multiline", "string", "literal"]
 license = "MIT OR Apache-2.0"
 repository = "https://github.com/dtolnay/indoc"
@@ -19,6 +20,9 @@ rustversion = "1.0"
 trybuild = { version = "1.0.108", features = ["diff"] }
 unindent = { version = "0.2.3", path = "unindent" }
 
+[build-dependencies]
+rustversion = "1.0"
+
 [workspace]
 members = ["unindent"]
 

build.rs

@@ -0,0 +1,9 @@
+fn main() {
+    // Warning: build.rs is not published to crates.io.
+
+    println!("cargo:rustc-check-cfg=cfg(indoc_test_cstr)");
+
+    if rustversion::cfg!(since(1.77)) {
+        println!("cargo:rustc-cfg=indoc_test_cstr");
+    }
+}

tests/test_cstr/mod.rs

@@ -0,0 +1,25 @@
+use indoc::indoc;
+
+#[test]
+fn c_string() {
+    let indoc = indoc! {c"
+        a
+
+            \\b
+        c"
+    };
+    let expected = c"a\n\n    \\b\nc";
+    assert_eq!(indoc, expected);
+}
+
+#[test]
+fn raw_c_string() {
+    let indoc = indoc! {cr#"
+        "a"
+
+            \\b
+        c"#
+    };
+    let expected = c"\"a\"\n\n    \\\\b\nc";
+    assert_eq!(indoc, expected);
+}

tests/test_indoc.rs

@@ -1,3 +1,6 @@
+#[cfg(indoc_test_cstr)]
+mod test_cstr;
+
 use indoc::indoc;
 
 const HELP: &str = indoc! {"
@@ -29,18 +32,6 @@ fn carriage_return() {
     assert_eq!(indoc, expected);
 }
 
-#[test]
-fn c_string() {
-    let indoc = indoc! {c"
-        a
-
-            \\b
-        c"
-    };
-    let expected = c"a\n\n    \\b\nc";
-    assert_eq!(indoc, expected);
-}
-
 #[test]
 fn empty_string() {
     let indoc = indoc! {""};
@@ -125,18 +116,6 @@ fn raw_byte_string() {
     assert_eq!(indoc, expected);
 }
 
-#[test]
-fn raw_c_string() {
-    let indoc = indoc! {cr#"
-        "a"
-
-            \\b
-        c"#
-    };
-    let expected = c"\"a\"\n\n    \\\\b\nc";
-    assert_eq!(indoc, expected);
-}
-
 #[test]
 fn raw_string() {
     let indoc = indoc! {r#"