[PATCH] D13192: Fix incorrect parsing of arguments for nested functions

Arseny Kapoulkine via cfe-commits cfe-commits at lists.llvm.org
Sat Sep 26 00:20:01 PDT 2015

arseny.kapoulkine created this revision.
arseny.kapoulkine added a subscriber: cfe-commits.

For nested functions, local-name can be followed by function arguments; in
some cases the first argument starts with a digit (if it's a named type).

For example, this code:

void test() { struct g { void foo(Point p); }; }

Generates this name for symbol foo:


When decomposed, this results in a local-name with entity name N1g3fooE
(aka g::foo). According to Itanium ABI, entity name can be followed by
a discriminator that has to start with _.

However, libcxxabi defines an extension that says that discriminator can start
with a digit. This makes the grammar ambiguous, and causes 5 to be skipped and
Point to be parsed as a series of types for function arguments.

Resolve ambiguity by requiring that a digit-only discriminator is the last
token in the input string.



Index: libcxxabi/trunk/test/test_demangle.pass.cpp
--- libcxxabi/trunk/test/test_demangle.pass.cpp
+++ libcxxabi/trunk/test/test_demangle.pass.cpp
@@ -29593,6 +29593,7 @@
     {"_ZNK3Ncr6Silver7Utility6detail12CallOnThreadIZ53-[DeploymentSetupController handleManualServerEntry:]E3$_5EclIJEEEDTclclL_ZNS2_4getTIS4_EERT_vEEspclsr3stdE7forwardIT_Efp_EEEDpOSA_", "decltype(-[DeploymentSetupController handleManualServerEntry:]::$_5& Ncr::Silver::Utility::detail::getT<-[DeploymentSetupController handleManualServerEntry:]::$_5>()()(std::forward<-[DeploymentSetupController handleManualServerEntry:]::$_5>(fp))) Ncr::Silver::Utility::detail::CallOnThread<-[DeploymentSetupController handleManualServerEntry:]::$_5>::operator()<>(-[DeploymentSetupController handleManualServerEntry:]::$_5&&) const"},
     {"_Zli2_xy", "operator\"\" _x(unsigned long long)"},
     {"_Z1fIiEDcT_", "decltype(auto) f<int>(int)"},
+    {"_ZZ4testvEN1g3fooE5Point", "test()::g::foo(Point)"},
 const unsigned N = sizeof(cases) / sizeof(cases[0]);
Index: libcxxabi/trunk/src/cxa_demangle.cpp
--- libcxxabi/trunk/src/cxa_demangle.cpp
+++ libcxxabi/trunk/src/cxa_demangle.cpp
@@ -4054,7 +4054,7 @@
 // <discriminator> := _ <non-negative number>      # when number < 10
 //                 := __ <non-negative number> _   # when number >= 10
-//  extension      := decimal-digit+
+//  extension      := decimal-digit+               # at the end of string
 const char*
 parse_discriminator(const char* first, const char* last)
@@ -4083,7 +4083,8 @@
             const char* t1 = first+1;
             for (; t1 != last && std::isdigit(*t1); ++t1)
-            first = t1;
+            if (t1 == last)
+                first = last;
     return first;

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