Merge pull request #630 from rben01/format-datetime-error

Improved formatting of `format_datetime` errors, including original jiff error

numbat/src/ffi/datetime.rs

@@ -1,4 +1,6 @@
 use compact_str::CompactString;
+use jiff::fmt::strtime::BrokenDownTime;
+use jiff::fmt::StdFmtWrite;
 use jiff::Span;
 use jiff::Timestamp;
 use jiff::Zoned;
@@ -13,8 +15,6 @@ use crate::value::FunctionReference;
 use crate::value::Value;
 use crate::RuntimeError;
 
-use std::fmt::Write;
-
 pub fn now(_args: Args) -> Result<Value> {
     return_datetime!(Zoned::now())
 }
@@ -33,7 +33,12 @@ pub fn format_datetime(mut args: Args) -> Result<Value> {
     let dt = datetime_arg!(args);
 
     let mut output = CompactString::with_capacity(format.len());
-    write!(output, "{}", dt.strftime(&format)).map_err(|_| RuntimeError::DateFormattingError)?;
+    BrokenDownTime::from(&dt)
+        // jiff::fmt::StdFmtWrite is a wrapper that turns an arbitrary std::fmt::Write
+        // into a jiff::fmt::Write, which is necessary to write a formatted datetime
+        // into it
+        .format(&format, StdFmtWrite(&mut output))
+        .map_err(|e| RuntimeError::DateFormattingError(e.to_string()))?;
 
     return_string!(owned = output)
 }

numbat/src/interpreter/mod.rs

@@ -48,8 +48,8 @@ pub enum RuntimeError {
     DurationOutOfRange,
     #[error("DateTime out of range")]
     DateTimeOutOfRange,
-    #[error("Error in datetime format. See https://docs.rs/jiff/latest/jiff/fmt/strtime/index.html#conversion-specifications for possible format specifiers.")]
-    DateFormattingError,
+    #[error("{0}. See https://docs.rs/jiff/latest/jiff/fmt/strtime/index.html#conversion-specifications for possible format specifiers.")]
+    DateFormattingError(String),
 
     #[error("Invalid format specifiers: {0}")]
     InvalidFormatSpecifiers(String),

numbat/tests/interpreter.rs

@@ -741,8 +741,12 @@ fn test_datetime_runtime_errors() {
     );
     expect_failure(
         "format_datetime(\"%Y-%m-%dT%H%:M\", now())",
-        "Error in datetime format",
-    )
+        "strftime formatting failed: found unrecognized directive %M following %:.",
+    );
+    expect_failure(
+        "format_datetime(\"%Y %;\", now())",
+        "strftime formatting failed: found unrecognized specifier directive %;.",
+    );
 }
 
 #[test]