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pretty: trim paths of unique symbols

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If a symbol name can only be imported from one place for a type, and
as long as it was not glob-imported anywhere in the current crate, we
can trim its printed path and print only the name.

This has wide implications on error messages with types, for example,
shortening `std::vec::Vec` to just `Vec`, as long as there is no other
`Vec` importable anywhere.

This adds a new '-Z trim-diagnostic-paths=false' option to control this
feature.

On the good path, with no diagnosis printed, we should try to avoid
issuing this query, so we need to prevent trimmed_def_paths query on
several cases.

This change also relies on a previous commit that differentiates
between `Debug` and `Display` on various rustc types, where the latter
is trimmed and presented to the user and the former is not.
This commit is contained in:
Dan Aloni 2020-09-02 10:40:56 +03:00
parent 7b2deb5628
commit 07e7823c01
1325 changed files with 4806 additions and 4546 deletions
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19
compiler/rustc_codegen_ssa/src/mir/block.rs
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@ -16,6 +16,7 @@ use rustc_middle::mir;
use rustc_middle::mir::interpret::{AllocId, ConstValue, Pointer, Scalar};
use rustc_middle::mir::AssertKind;
use rustc_middle::ty::layout::{FnAbiExt, HasTyCtxt};
use rustc_middle::ty::print::with_no_trimmed_paths;
use rustc_middle::ty::{self, Instance, Ty, TypeFoldable};
use rustc_span::source_map::Span;
use rustc_span::{sym, Symbol};
@ -479,14 +480,16 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
UninitValid => !layout.might_permit_raw_init(bx, /*zero:*/ false).unwrap(),
};
if do_panic {
let msg_str = if layout.abi.is_uninhabited() {
// Use this error even for the other intrinsics as it is more precise.
format!("attempted to instantiate uninhabited type `{}`", ty)
} else if intrinsic == ZeroValid {
format!("attempted to zero-initialize type `{}`, which is invalid", ty)
} else {
format!("attempted to leave type `{}` uninitialized, which is invalid", ty)
};
let msg_str = with_no_trimmed_paths(|| {
if layout.abi.is_uninhabited() {
// Use this error even for the other intrinsics as it is more precise.
format!("attempted to instantiate uninhabited type `{}`", ty)
} else if intrinsic == ZeroValid {
format!("attempted to zero-initialize type `{}`, which is invalid", ty)
} else {
format!("attempted to leave type `{}` uninitialized, which is invalid", ty)
}
});
let msg = bx.const_str(Symbol::intern(&msg_str));
let location = self.get_caller_location(bx, span).immediate();