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Improved non_exhaustive message.

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This commit is contained in:
David Wood
2018-06-30 20:03:51 +01:00
parent 039709d34f
commit 3e59aef385
1 changed files with 29 additions and 16 deletions
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45
src/librustdoc/html/render.rs
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@@ -2265,22 +2265,35 @@ fn document_stability(w: &mut fmt::Formatter, cx: &Context, item: &clean::Item)
fn document_non_exhaustive(w: &mut fmt::Formatter, item: &clean::Item) -> fmt::Result {
if item.non_exhaustive {
let name = item.type_();
write!(w, r##"
<div class='non-exhaustive'>
<div class='stab non-exhaustive'>
<details>
<summary>
<span class=microscope>🔬</span>
This {} is marked as non exhaustive.
</summary>
<p>
This {} will require a wildcard arm in any match statements or constructors.
</p>
</details>
</div>
</div>
"##, name, name)?;
write!(w, "<div class='non-exhaustive'><div class='stab non-exhaustive'>")?;
write!(w, "<details><summary><span class=microscope>🔬</span>")?;
if item.is_struct() {
write!(w, "This struct is marked as non exhaustive.")?;
} else if item.is_enum() {
write!(w, "This enum is marked as non exhaustive.")?;
} else {
write!(w, "This type is marked as non exhaustive.")?;
}
write!(w, "</summary><p>")?;
if item.is_struct() {
write!(w, "This struct is marked as non-exhaustive as additional fields may be \
added in the future. This means that this struct cannot be constructed in \
external crates using the traditional <code>Struct {{ .. }}</code> syntax;
cannot be matched against without a wildcard <code>..</code>; and \
functional-record-updates do not work on this struct.")?;
} else if item.is_enum() {
write!(w, "This enum is marked as non-exhaustive, and additional variants may be \
added in the future. When matching over values of this type, an extra \
<code>_</code> arm must be added to account for future extensions.")?;
} else {
write!(w, "This type will require a wildcard arm in any match statements or \
constructors.")?;
}
write!(w, "</p></details></div></div>")?;
}
Ok(())