1 files changed, 133 insertions, 0 deletions
diff --git a/vendor/proc-macro2/build.rs b/vendor/proc-macro2/build.rs
new file mode 100644
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--- /dev/null
+++ b/vendor/proc-macro2/build.rs
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+// rustc-cfg emitted by the build script:
+//
+// "wrap_proc_macro"
+//     Wrap types from libproc_macro rather than polyfilling the whole API.
+//     Enabled on rustc 1.29+ as long as procmacro2_semver_exempt is not set,
+//     because we can't emulate the unstable API without emulating everything
+//     else. Also enabled unconditionally on nightly, in which case the
+//     procmacro2_semver_exempt surface area is implemented by using the
+//     nightly-only proc_macro API.
+//
+// "hygiene"
+//    Enable Span::mixed_site() and non-dummy behavior of Span::resolved_at
+//    and Span::located_at. Enabled on Rust 1.45+.
+//
+// "proc_macro_span"
+//     Enable non-dummy behavior of Span::start and Span::end methods which
+//     requires an unstable compiler feature. Enabled when building with
+//     nightly, unless `-Z allow-feature` in RUSTFLAGS disallows unstable
+//     features.
+//
+// "super_unstable"
+//     Implement the semver exempt API in terms of the nightly-only proc_macro
+//     API. Enabled when using procmacro2_semver_exempt on a nightly compiler.
+//
+// "span_locations"
+//     Provide methods Span::start and Span::end which give the line/column
+//     location of a token. Enabled by procmacro2_semver_exempt or the
+//     "span-locations" Cargo cfg. This is behind a cfg because tracking
+//     location inside spans is a performance hit.
+//
+// "is_available"
+//     Use proc_macro::is_available() to detect if the proc macro API is
+//     available or needs to be polyfilled instead of trying to use the proc
+//     macro API and catching a panic if it isn't available. Enabled on Rust
+//     1.57+.
+
+use std::env;
+use std::process::Command;
+use std::str;
+use std::u32;
+
+fn main() {
+    println!("cargo:rerun-if-changed=build.rs");
+
+    let version = rustc_version().unwrap_or(RustcVersion {
+        minor: u32::MAX,
+        nightly: false,
+    });
+
+    let docs_rs = env::var_os("DOCS_RS").is_some();
+    let semver_exempt = cfg!(procmacro2_semver_exempt) || docs_rs;
+    if semver_exempt {
+        // https://github.com/dtolnay/proc-macro2/issues/147
+        println!("cargo:rustc-cfg=procmacro2_semver_exempt");
+    }
+
+    if semver_exempt || cfg!(feature = "span-locations") {
+        println!("cargo:rustc-cfg=span_locations");
+    }
+
+    if version.minor < 57 {
+        println!("cargo:rustc-cfg=no_is_available");
+    }
+
+    if version.minor < 66 {
+        println!("cargo:rustc-cfg=no_source_text");
+    }
+
+    if !cfg!(feature = "proc-macro") {
+        return;
+    }
+
+    if version.nightly || !semver_exempt {
+        println!("cargo:rustc-cfg=wrap_proc_macro");
+    }
+
+    if version.nightly && feature_allowed("proc_macro_span") {
+        println!("cargo:rustc-cfg=proc_macro_span");
+    }
+
+    if semver_exempt && version.nightly {
+        println!("cargo:rustc-cfg=super_unstable");
+    }
+}
+
+struct RustcVersion {
+    minor: u32,
+    nightly: bool,
+}
+
+fn rustc_version() -> Option<RustcVersion> {
+    let rustc = env::var_os("RUSTC")?;
+    let output = Command::new(rustc).arg("--version").output().ok()?;
+    let version = str::from_utf8(&output.stdout).ok()?;
+    let nightly = version.contains("nightly") || version.contains("dev");
+    let mut pieces = version.split('.');
+    if pieces.next() != Some("rustc 1") {
+        return None;
+    }
+    let minor = pieces.next()?.parse().ok()?;
+    Some(RustcVersion { minor, nightly })
+}
+
+fn feature_allowed(feature: &str) -> bool {
+    // Recognized formats:
+    //
+    //     -Z allow-features=feature1,feature2
+    //
+    //     -Zallow-features=feature1,feature2
+
+    let flags_var;
+    let flags_var_string;
+    let flags = if let Some(encoded_rustflags) = env::var_os("CARGO_ENCODED_RUSTFLAGS") {
+        flags_var = encoded_rustflags;
+        flags_var_string = flags_var.to_string_lossy();
+        flags_var_string.split('\x1f')
+    } else {
+        return true;
+    };
+
+    for mut flag in flags {
+        if flag.starts_with("-Z") {
+            flag = &flag["-Z".len()..];
+        }
+        if flag.starts_with("allow-features=") {
+            flag = &flag["allow-features=".len()..];
+            return flag.split(',').any(|allowed| allowed == feature);
+        }
+    }
+
+    // No allow-features= flag, allowed by default.
+    true
+}