From 14e6947fa4b9a144802869286a937c987d6a3c54 Mon Sep 17 00:00:00 2001
From: varkor <github@varkor.com>
Date: Tue, 10 Sep 2019 18:46:27 +0100
Subject: [PATCH 1/2] Correct the polymorphic extern fn error for const
parameters
---
src/librustc_typeck/check/mod.rs | 33 +++++++++++++++----
.../foreign-item-const-parameter.rs | 10 ++++++
.../foreign-item-const-parameter.stderr | 27 +++++++++++++++
3 files changed, 63 insertions(+), 7 deletions(-)
create mode 100644 src/test/ui/const-generics/foreign-item-const-parameter.rs
create mode 100644 src/test/ui/const-generics/foreign-item-const-parameter.stderr
diff --git a/src/librustc_typeck/check/mod.rs b/src/librustc_typeck/check/mod.rs
index d8d01624f1d56..e76ef14f06c87 100644
--- a/src/librustc_typeck/check/mod.rs
+++ b/src/librustc_typeck/check/mod.rs
@@ -1511,20 +1511,39 @@ pub fn check_item_type<'tcx>(tcx: TyCtxt<'tcx>, it: &'tcx hir::Item) {
} else {
for item in &m.items {
let generics = tcx.generics_of(tcx.hir().local_def_id(item.hir_id));
- if generics.params.len() - generics.own_counts().lifetimes != 0 {
+ let own_counts = generics.own_counts();
+ if generics.params.len() - own_counts.lifetimes != 0 {
+ let (kinds, kinds_pl, egs) = match (own_counts.types, own_counts.consts) {
+ (_, 0) => ("type", "types", Some("u32")),
+ // We don't specify an example value, because we can't generate
+ // a valid value for any type.
+ (0, _) => ("const", "consts", None),
+ _ => ("type or const", "types or consts", None),
+ };
let mut err = struct_span_err!(
tcx.sess,
item.span,
E0044,
- "foreign items may not have type parameters"
+ "foreign items may not have {} parameters",
+ kinds,
+ );
+ err.span_label(
+ item.span,
+ &format!("can't have {} parameters", kinds),
);
- err.span_label(item.span, "can't have type parameters");
// FIXME: once we start storing spans for type arguments, turn this into a
// suggestion.
- err.help(
- "use specialization instead of type parameters by replacing them \
- with concrete types like `u32`",
- );
+ err.help(&format!(
+ "use specialization instead of {} parameters by replacing \
+ them with concrete {}{}",
+ kinds,
+ kinds_pl,
+ if let Some(egs) = egs {
+ format!(" like `{}`", egs)
+ } else {
+ "".to_string()
+ },
+ ));
err.emit();
}
diff --git a/src/test/ui/const-generics/foreign-item-const-parameter.rs b/src/test/ui/const-generics/foreign-item-const-parameter.rs
new file mode 100644
index 0000000000000..4673c8606c393
--- /dev/null
+++ b/src/test/ui/const-generics/foreign-item-const-parameter.rs
@@ -0,0 +1,10 @@
+#![feature(const_generics)]
+//~^ WARN the feature `const_generics` is incomplete and may cause the compiler to crash
+
+extern "C" {
+ fn foo<const X: usize>(); //~ ERROR foreign items may not have const parameters
+
+ fn bar<T, const X: usize>(_: T); //~ ERROR foreign items may not have type or const parameters
+}
+
+fn main() {}
diff --git a/src/test/ui/const-generics/foreign-item-const-parameter.stderr b/src/test/ui/const-generics/foreign-item-const-parameter.stderr
new file mode 100644
index 0000000000000..0a74537dfef35
--- /dev/null
+++ b/src/test/ui/const-generics/foreign-item-const-parameter.stderr
@@ -0,0 +1,27 @@
+warning: the feature `const_generics` is incomplete and may cause the compiler to crash
+ --> $DIR/foreign-item-const-parameter.rs:1:12
+ |
+LL | #![feature(const_generics)]
+ | ^^^^^^^^^^^^^^
+ |
+ = note: `#[warn(incomplete_features)]` on by default
+
+error[E0044]: foreign items may not have const parameters
+ --> $DIR/foreign-item-const-parameter.rs:5:5
+ |
+LL | fn foo<const X: usize>();
+ | ^^^^^^^^^^^^^^^^^^^^^^^^^ can't have const parameters
+ |
+ = help: use specialization instead of const parameters by replacing them with concrete consts
+
+error[E0044]: foreign items may not have type or const parameters
+ --> $DIR/foreign-item-const-parameter.rs:7:5
+ |
+LL | fn bar<T, const X: usize>(_: T);
+ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ can't have type or const parameters
+ |
+ = help: use specialization instead of type or const parameters by replacing them with concrete types or consts
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0044`.
From ef62e050624fabc57f17dd6744ff29f79b39e8cd Mon Sep 17 00:00:00 2001
From: varkor <github@varkor.com>
Date: Tue, 10 Sep 2019 22:35:10 +0100
Subject: [PATCH 2/2] Make wording less confusing
---
src/librustc_typeck/check/mod.rs | 30 ++++++++-----------
.../foreign-item-const-parameter.stderr | 4 +--
src/test/ui/error-codes/E0044.rs | 2 +-
src/test/ui/error-codes/E0044.stderr | 2 +-
src/test/ui/generic/generic-extern.stderr | 2 +-
5 files changed, 17 insertions(+), 23 deletions(-)
diff --git a/src/librustc_typeck/check/mod.rs b/src/librustc_typeck/check/mod.rs
index e76ef14f06c87..02e7d97ccdf7b 100644
--- a/src/librustc_typeck/check/mod.rs
+++ b/src/librustc_typeck/check/mod.rs
@@ -1520,31 +1520,25 @@ pub fn check_item_type<'tcx>(tcx: TyCtxt<'tcx>, it: &'tcx hir::Item) {
(0, _) => ("const", "consts", None),
_ => ("type or const", "types or consts", None),
};
- let mut err = struct_span_err!(
+ struct_span_err!(
tcx.sess,
item.span,
E0044,
"foreign items may not have {} parameters",
kinds,
- );
- err.span_label(
+ ).span_label(
item.span,
&format!("can't have {} parameters", kinds),
- );
- // FIXME: once we start storing spans for type arguments, turn this into a
- // suggestion.
- err.help(&format!(
- "use specialization instead of {} parameters by replacing \
- them with concrete {}{}",
- kinds,
- kinds_pl,
- if let Some(egs) = egs {
- format!(" like `{}`", egs)
- } else {
- "".to_string()
- },
- ));
- err.emit();
+ ).help(
+ // FIXME: once we start storing spans for type arguments, turn this
+ // into a suggestion.
+ &format!(
+ "replace the {} parameters with concrete {}{}",
+ kinds,
+ kinds_pl,
+ egs.map(|egs| format!(" like `{}`", egs)).unwrap_or_default(),
+ ),
+ ).emit();
}
if let hir::ForeignItemKind::Fn(ref fn_decl, _, _) = item.node {
diff --git a/src/test/ui/const-generics/foreign-item-const-parameter.stderr b/src/test/ui/const-generics/foreign-item-const-parameter.stderr
index 0a74537dfef35..999feed2d3b20 100644
--- a/src/test/ui/const-generics/foreign-item-const-parameter.stderr
+++ b/src/test/ui/const-generics/foreign-item-const-parameter.stderr
@@ -12,7 +12,7 @@ error[E0044]: foreign items may not have const parameters
LL | fn foo<const X: usize>();
| ^^^^^^^^^^^^^^^^^^^^^^^^^ can't have const parameters
|
- = help: use specialization instead of const parameters by replacing them with concrete consts
+ = help: replace the const parameters with concrete consts
error[E0044]: foreign items may not have type or const parameters
--> $DIR/foreign-item-const-parameter.rs:7:5
@@ -20,7 +20,7 @@ error[E0044]: foreign items may not have type or const parameters
LL | fn bar<T, const X: usize>(_: T);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ can't have type or const parameters
|
- = help: use specialization instead of type or const parameters by replacing them with concrete types or consts
+ = help: replace the type or const parameters with concrete types or consts
error: aborting due to 2 previous errors
diff --git a/src/test/ui/error-codes/E0044.rs b/src/test/ui/error-codes/E0044.rs
index a5265e7dc1708..9eee9c31d3c38 100644
--- a/src/test/ui/error-codes/E0044.rs
+++ b/src/test/ui/error-codes/E0044.rs
@@ -1,7 +1,7 @@
extern {
fn sqrt<T>(f: T) -> T;
//~^ ERROR foreign items may not have type parameters [E0044]
- //~| HELP use specialization instead of type parameters by replacing them with concrete types
+ //~| HELP replace the type parameters with concrete types
//~| NOTE can't have type parameters
}
diff --git a/src/test/ui/error-codes/E0044.stderr b/src/test/ui/error-codes/E0044.stderr
index 57c21116b2856..e889c167b98d2 100644
--- a/src/test/ui/error-codes/E0044.stderr
+++ b/src/test/ui/error-codes/E0044.stderr
@@ -4,7 +4,7 @@ error[E0044]: foreign items may not have type parameters
LL | fn sqrt<T>(f: T) -> T;
| ^^^^^^^^^^^^^^^^^^^^^^ can't have type parameters
|
- = help: use specialization instead of type parameters by replacing them with concrete types like `u32`
+ = help: replace the type parameters with concrete types like `u32`
error: aborting due to previous error
diff --git a/src/test/ui/generic/generic-extern.stderr b/src/test/ui/generic/generic-extern.stderr
index e7625abb1c831..c90215b612d4c 100644
--- a/src/test/ui/generic/generic-extern.stderr
+++ b/src/test/ui/generic/generic-extern.stderr
@@ -4,7 +4,7 @@ error[E0044]: foreign items may not have type parameters
LL | fn foo<T>();
| ^^^^^^^^^^^^ can't have type parameters
|
- = help: use specialization instead of type parameters by replacing them with concrete types like `u32`
+ = help: replace the type parameters with concrete types like `u32`
error: aborting due to previous error