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Derived Eq no longer shows uncovered

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The Eq trait has a special hidden function. MIR `InstrumentCoverage`
would add this function to the coverage map, but it is never called, so
the `Eq` trait would always appear uncovered.

Fixes: #83601

The fix required creating a new function attribute `no_coverage` to mark
functions that should be ignored by `InstrumentCoverage` and the
coverage `mapgen` (during codegen).

While testing, I also noticed two other issues:

* spanview debug file output ICEd on a function with no body. The
workaround for this is included in this PR.
* `assert_*!()` macro coverage can appear covered if followed by another
`assert_*!()` macro. Normally they appear uncovered. I submitted a new
Issue #84561, and added a coverage test to demonstrate this issue.
This commit is contained in:
Rich Kadel 2021-04-25 13:34:03 -07:00
parent 1919b3f227
commit 888d0b4c96
13 changed files with 119 additions and 2 deletions
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6
compiler/rustc_mir/src/transform/coverage/mod.rs
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@ -23,6 +23,7 @@ use rustc_index::vec::IndexVec;
use rustc_middle::hir;
use rustc_middle::hir::map::blocks::FnLikeNode;
use rustc_middle::ich::StableHashingContext;
use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrFlags;
use rustc_middle::mir::coverage::*;
use rustc_middle::mir::{
self, BasicBlock, BasicBlockData, Coverage, SourceInfo, Statement, StatementKind, Terminator,
@ -87,6 +88,11 @@ impl<'tcx> MirPass<'tcx> for InstrumentCoverage {
_ => {}
}
let codegen_fn_attrs = tcx.codegen_fn_attrs(mir_source.def_id());
if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::NO_COVERAGE) {
return;
}
trace!("InstrumentCoverage starting for {:?}", mir_source.def_id());
Instrumentor::new(&self.name(), tcx, mir_body).inject_counters();
trace!("InstrumentCoverage starting for {:?}", mir_source.def_id());