bjoernager/rust
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improve const infer err

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This commit is contained in:
Bastian Kauschke 2020-09-14 10:08:32 +02:00
parent dd57275c3e
commit 035f879166
9 changed files with 20 additions and 9 deletions
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14
compiler/rustc_infer/src/infer/error_reporting/need_type_info.rs
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@ -6,6 +6,7 @@ use rustc_hir::def::{DefKind, Namespace};
use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
use rustc_hir::{Body, Expr, ExprKind, FnRetTy, HirId, Local, Pat};
use rustc_middle::hir::map::Map;
use rustc_middle::infer::unify_key::ConstVariableOriginKind;
use rustc_middle::ty::print::Print;
use rustc_middle::ty::subst::{GenericArg, GenericArgKind};
use rustc_middle::ty::{self, DefIdTree, InferConst, Ty};
@ -569,8 +570,13 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
local_visitor.visit_expr(expr);
}
let mut param_name = None;
let span = if let ty::ConstKind::Infer(InferConst::Var(vid)) = ct.val {
self.inner.borrow_mut().const_unification_table().probe_value(vid).origin.span
let origin = self.inner.borrow_mut().const_unification_table().probe_value(vid).origin;
if let ConstVariableOriginKind::ConstParameterDefinition(param) = origin.kind {
param_name = Some(param);
}
origin.span
} else {
local_visitor.target_span
};
@ -579,7 +585,11 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
let mut err =
self.tcx.sess.struct_span_err_with_code(span, "type annotations needed", error_code);
err.note("unable to infer the value of a const parameter");
if let Some(param_name) = param_name {
err.note(&format!("cannot infer the value of the const parameter `{}`", param_name));
} else {
err.note("unable to infer the value of a const parameter");
}
err
}