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Prevent repr(C, u8) from triggering a warning on non-clike enums

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This commit is contained in:
Alexis Beingessner 2017-11-20 12:26:54 -05:00
parent 8293fe9fdf
commit 3d7a6fee79
1 changed files with 25 additions and 5 deletions
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30
src/librustc/hir/check_attr.rs
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@ -75,7 +75,9 @@ impl<'a> CheckAttrVisitor<'a> {
} }
}; };
let mut conflicting_reprs = 0; let mut int_reprs = 0;
let mut is_c = false;
let mut is_simd = false;
for word in words { for word in words {
@ -86,7 +88,7 @@ impl<'a> CheckAttrVisitor<'a> {
let (message, label) = match &*name.as_str() { let (message, label) = match &*name.as_str() {
"C" => { "C" => {
conflicting_reprs += 1; is_c = true;
if target != Target::Struct && if target != Target::Struct &&
target != Target::Union && target != Target::Union &&
target != Target::Enum { target != Target::Enum {
@ -108,7 +110,7 @@ impl<'a> CheckAttrVisitor<'a> {
} }
} }
"simd" => { "simd" => {
conflicting_reprs += 1; is_simd = true;
if target != Target::Struct { if target != Target::Struct {
("attribute should be applied to struct", ("attribute should be applied to struct",
"a struct") "a struct")
@ -128,7 +130,7 @@ impl<'a> CheckAttrVisitor<'a> {
"i8" | "u8" | "i16" | "u16" | "i8" | "u8" | "i16" | "u16" |
"i32" | "u32" | "i64" | "u64" | "i32" | "u32" | "i64" | "u64" |
"isize" | "usize" => { "isize" | "usize" => {
conflicting_reprs += 1; int_reprs += 1;
if target != Target::Enum { if target != Target::Enum {
("attribute should be applied to enum", ("attribute should be applied to enum",
"an enum") "an enum")
@ -142,7 +144,11 @@ impl<'a> CheckAttrVisitor<'a> {
.span_label(item.span, format!("not {}", label)) .span_label(item.span, format!("not {}", label))
.emit(); .emit();
} }
if conflicting_reprs > 1 {
// Warn on repr(u8, u16), repr(C, simd), and c-like-enum-repr(C, u8)
if (int_reprs > 1)
|| (is_simd && is_c)
|| (int_reprs == 1 && is_c && is_c_like_enum(item)) {
span_warn!(self.sess, attr.span, E0566, span_warn!(self.sess, attr.span, E0566,
"conflicting representation hints"); "conflicting representation hints");
} }
@ -162,3 +168,17 @@ impl<'a> Visitor<'a> for CheckAttrVisitor<'a> {
pub fn check_crate(sess: &Session, krate: &ast::Crate) { pub fn check_crate(sess: &Session, krate: &ast::Crate) {
visit::walk_crate(&mut CheckAttrVisitor { sess: sess }, krate); visit::walk_crate(&mut CheckAttrVisitor { sess: sess }, krate);
} }
fn is_c_like_enum(item: &ast::Item) -> bool {
if let ast::ItemKind::Enum(ref def, _) = item.node {
for variant in &def.variants {
match variant.node.data {
ast::VariantData::Unit(_) => { /* continue */ }
_ => { return false; }
}
}
true
} else {
false
}
}