Demangle Rust backrefs.

PiperOrigin-RevId: 633738511
Change-Id: I3f895d5de1aec5b5b9666523a328f3a3b0344e59

1 files changed, 66 insertions, 0 deletions

diff --git a/absl/debugging/internal/demangle_rust_test.cc b/absl/debugging/internal/demangle_rust_test.cc
index a8ef60d6..c931304d 100644
--- a/absl/debugging/internal/demangle_rust_test.cc
+++ b/absl/debugging/internal/demangle_rust_test.cc
@@ -294,6 +294,72 @@ TEST(DemangleRust, LongerTuplesAbbreviated) {
                     "<(i32, u32, i128, ...) as c::t>::f");
 }
 
+TEST(DemangleRust, PathBackrefToCrate) {
+  EXPECT_DEMANGLING("_RNvYNtC8my_crate9my_structNtB4_8my_trait1f",
+                    "<my_crate::my_struct as my_crate::my_trait>::f");
+}
+
+TEST(DemangleRust, PathBackrefToNestedPath) {
+  EXPECT_DEMANGLING("_RNvYNtNtC1c1m1sNtB4_1t1f", "<c::m::s as c::m::t>::f");
+}
+
+TEST(DemangleRust, PathBackrefAsInstantiatingCrate) {
+  EXPECT_DEMANGLING("_RNCNvC8my_crate7my_func0B3_",
+                    "my_crate::my_func::{closure#0}");
+}
+
+TEST(DemangleRust, TypeBackrefsNestedInTuple) {
+  EXPECT_DEMANGLING("_RNvYTTRlB4_ERB3_ENtC1c1t1f",
+                    "<((&i32, &i32), &(&i32, &i32)) as c::t>::f");
+}
+
+TEST(DemangleRust, NoInfiniteLoopOnBackrefToTheWhole) {
+  EXPECT_DEMANGLING_FAILS("_RB_");
+  EXPECT_DEMANGLING_FAILS("_RNvB_1sNtC1c1t1f");
+}
+
+TEST(DemangleRust, NoCrashOnForwardBackref) {
+  EXPECT_DEMANGLING_FAILS("_RB0_");
+  EXPECT_DEMANGLING_FAILS("_RB1_");
+  EXPECT_DEMANGLING_FAILS("_RB2_");
+  EXPECT_DEMANGLING_FAILS("_RB3_");
+  EXPECT_DEMANGLING_FAILS("_RB4_");
+}
+
+TEST(DemangleRust, PathBackrefsDoNotRecurseDuringSilence) {
+  // B_ points at the value f (the whole mangling), so the cycle would lead to
+  // parse failure if the parser tried to parse what was pointed to.
+  EXPECT_DEMANGLING("_RNvYTlmnNtB_1sENtC1c1t1f",
+                    "<(i32, u32, i128, ...) as c::t>::f");
+}
+
+TEST(DemangleRust, TypeBackrefsDoNotRecurseDuringSilence) {
+  // B2_ points at the tuple type, likewise making a cycle that the parser
+  // avoids following.
+  EXPECT_DEMANGLING("_RNvYTlmnB2_ENtC1c1t1f",
+                    "<(i32, u32, i128, ...) as c::t>::f");
+}
+
+TEST(DemangleRust, ReturnFromBackrefToInputPosition256) {
+  // Show that we can resume at input positions that don't fit into a byte.
+  EXPECT_DEMANGLING("_RNvYNtC1c238very_long_type_"
+                    "ABCDEFGHIJabcdefghijABCDEFGHIJabcdefghij"
+                    "ABCDEFGHIJabcdefghijABCDEFGHIJabcdefghij"
+                    "ABCDEFGHIJabcdefghijABCDEFGHIJabcdefghij"
+                    "ABCDEFGHIJabcdefghijABCDEFGHIJabcdefghij"
+                    "ABCDEFGHIJabcdefghijABCDEFGHIJabcdefghij"
+                    "ABCDEFGHIJabcdefghijABC"
+                    "NtB4_1t1f",
+                    "<c::very_long_type_"
+                    "ABCDEFGHIJabcdefghijABCDEFGHIJabcdefghij"
+                    "ABCDEFGHIJabcdefghijABCDEFGHIJabcdefghij"
+                    "ABCDEFGHIJabcdefghijABCDEFGHIJabcdefghij"
+                    "ABCDEFGHIJabcdefghijABCDEFGHIJabcdefghij"
+                    "ABCDEFGHIJabcdefghijABCDEFGHIJabcdefghij"
+                    "ABCDEFGHIJabcdefghijABC"
+                    " as c::t>::f");
+}
+
 }  // namespace
 }  // namespace debugging_internal
 ABSL_NAMESPACE_END