1 files changed, 123 insertions, 0 deletions
diff --git a/third_party/rust/time-macros/src/error.rs b/third_party/rust/time-macros/src/error.rs
new file mode 100644
index 0000000000..849317f15f
--- /dev/null
+++ b/third_party/rust/time-macros/src/error.rs
@@ -0,0 +1,123 @@
+use std::borrow::Cow;
+use std::fmt;
+
+use proc_macro::{Delimiter, Group, Ident, Literal, Punct, Spacing, Span, TokenStream, TokenTree};
+
+trait WithSpan {
+    fn with_span(self, span: Span) -> Self;
+}
+
+impl WithSpan for TokenTree {
+    fn with_span(mut self, span: Span) -> Self {
+        self.set_span(span);
+        self
+    }
+}
+
+pub(crate) enum Error {
+    MissingComponent {
+        name: &'static str,
+        span_start: Option<Span>,
+        span_end: Option<Span>,
+    },
+    InvalidComponent {
+        name: &'static str,
+        value: String,
+        span_start: Option<Span>,
+        span_end: Option<Span>,
+    },
+    #[cfg(any(feature = "formatting", feature = "parsing"))]
+    ExpectedString {
+        span_start: Option<Span>,
+        span_end: Option<Span>,
+    },
+    UnexpectedToken {
+        tree: TokenTree,
+    },
+    UnexpectedEndOfInput,
+    Custom {
+        message: Cow<'static, str>,
+        span_start: Option<Span>,
+        span_end: Option<Span>,
+    },
+}
+
+impl fmt::Display for Error {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::MissingComponent { name, .. } => write!(f, "missing component: {name}"),
+            Self::InvalidComponent { name, value, .. } => {
+                write!(f, "invalid component: {name} was {value}")
+            }
+            #[cfg(any(feature = "formatting", feature = "parsing"))]
+            Self::ExpectedString { .. } => f.write_str("expected string literal"),
+            Self::UnexpectedToken { tree } => write!(f, "unexpected token: {tree}"),
+            Self::UnexpectedEndOfInput => f.write_str("unexpected end of input"),
+            Self::Custom { message, .. } => f.write_str(message),
+        }
+    }
+}
+
+impl Error {
+    fn span_start(&self) -> Span {
+        match self {
+            Self::MissingComponent { span_start, .. }
+            | Self::InvalidComponent { span_start, .. }
+            | Self::Custom { span_start, .. } => *span_start,
+            #[cfg(any(feature = "formatting", feature = "parsing"))]
+            Self::ExpectedString { span_start, .. } => *span_start,
+            Self::UnexpectedToken { tree } => Some(tree.span()),
+            Self::UnexpectedEndOfInput => Some(Span::mixed_site()),
+        }
+        .unwrap_or_else(Span::mixed_site)
+    }
+
+    fn span_end(&self) -> Span {
+        match self {
+            Self::MissingComponent { span_end, .. }
+            | Self::InvalidComponent { span_end, .. }
+            | Self::Custom { span_end, .. } => *span_end,
+            #[cfg(any(feature = "formatting", feature = "parsing"))]
+            Self::ExpectedString { span_end, .. } => *span_end,
+            Self::UnexpectedToken { tree, .. } => Some(tree.span()),
+            Self::UnexpectedEndOfInput => Some(Span::mixed_site()),
+        }
+        .unwrap_or_else(|| self.span_start())
+    }
+
+    pub(crate) fn to_compile_error(&self) -> TokenStream {
+        let (start, end) = (self.span_start(), self.span_end());
+
+        [
+            TokenTree::from(Punct::new(':', Spacing::Joint)).with_span(start),
+            TokenTree::from(Punct::new(':', Spacing::Alone)).with_span(start),
+            TokenTree::from(Ident::new("core", start)),
+            TokenTree::from(Punct::new(':', Spacing::Joint)).with_span(start),
+            TokenTree::from(Punct::new(':', Spacing::Alone)).with_span(start),
+            TokenTree::from(Ident::new("compile_error", start)),
+            TokenTree::from(Punct::new('!', Spacing::Alone)).with_span(start),
+            TokenTree::from(Group::new(
+                Delimiter::Parenthesis,
+                TokenStream::from(
+                    TokenTree::from(Literal::string(&self.to_string())).with_span(end),
+                ),
+            ))
+            .with_span(end),
+        ]
+        .iter()
+        .cloned()
+        .collect()
+    }
+
+    /// Like `to_compile_error`, but for use in macros that produce items.
+    #[cfg(all(feature = "serde", any(feature = "formatting", feature = "parsing")))]
+    pub(crate) fn to_compile_error_standalone(&self) -> TokenStream {
+        let end = self.span_end();
+        self.to_compile_error()
+            .into_iter()
+            .chain(std::iter::once(
+                TokenTree::from(Punct::new(';', Spacing::Alone)).with_span(end),
+            ))
+            .collect()
+    }
+}