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Fix stack overflow when generating debuginfo for 'recursive' type #59446

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merged 6 commits into from
Apr 2, 2019
Merged

Fix stack overflow when generating debuginfo for 'recursive' type #59446

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512069f
Fix stack overflow when generating debuginfo for 'recursive' type
Aaron1011 Mar 26, 2019
e1837a0
Fix inverted panic check
Aaron1011 Mar 26, 2019
aed7ec4
Add codegen test
Aaron1011 Mar 27, 2019
c4556a5
Fix typos
Aaron1011 Mar 28, 2019
d2584e3
Only track 'visited' state for function types
Aaron1011 Apr 1, 2019
c13daeb
Fix typo
Aaron1011 Apr 1, 2019
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49 changes: 31 additions & 18 deletions src/librustc_codegen_llvm/debuginfo/type_names.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -31,24 +31,6 @@ pub fn push_debuginfo_type_name<'a, 'tcx>(cx: &CodegenCx<'a, 'tcx>,
output: &mut String,
visited: &mut FxHashSet<Ty<'tcx>>) {

// We've encountered a weird 'recursive type'
// Currently, the only way to generate such a type
// is by using 'impl trait':
//
// fn foo() -> impl Copy { foo }
//
// There's not really a sensible name we can generate,
// since we don't include 'impl trait' types (e.g. ty::Opaque)
// in the output
//
// Since we need to generate *something*, we just
// use a dummy string that should make it clear
// that something unusual is going on
if !visited.insert(t) {
output.push_str("<recursive_type>");
return;
}

// When targeting MSVC, emit C++ style type names for compatibility with
// .natvis visualizers (and perhaps other existing native debuggers?)
let cpp_like_names = cx.sess().target.target.options.is_like_msvc;
Expand Down Expand Up @@ -141,6 +123,25 @@ pub fn push_debuginfo_type_name<'a, 'tcx>(cx: &CodegenCx<'a, 'tcx>,
}
},
ty::FnDef(..) | ty::FnPtr(_) => {
// We've encountered a weird 'recursive type'
// Currently, the only way to generate such a type
// is by using 'impl trait':
//
// fn foo() -> impl Copy { foo }
//
// There's not really a sensible name we can generate,
// since we don't include 'impl trait' types (e.g. ty::Opaque)
// in the output
//
// Since we need to generate *something*, we just
// use a dummy string that should make it clear
// that something unusual is going on
if !visited.insert(t) {
output.push_str("<recursive_type>");
return;
}


let sig = t.fn_sig(cx.tcx);
if sig.unsafety() == hir::Unsafety::Unsafe {
output.push_str("unsafe ");
Expand Down Expand Up @@ -179,6 +180,18 @@ pub fn push_debuginfo_type_name<'a, 'tcx>(cx: &CodegenCx<'a, 'tcx>,
output.push_str(" -> ");
push_debuginfo_type_name(cx, sig.output(), true, output, visited);
}


// We only keep the type in 'visited'
// for the duration of the body of this method.
// It's fine for a particular function type
// to show up multiple times in one overall type
// (e.g. MyType<fn() -> u8, fn() -> u8>
//
// We only care about avoiding recursing
// directly back to the type we're currentlu
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typo: "currentlu" should be "currently"

// processing
visited.remove(t);
},
ty::Closure(..) => {
output.push_str("closure");
Expand Down