libiberty: Add Rust symbol demangling.

Adds Rust symbol demangler. Rust mangles symbols using GNU_V3 style,
adding a hash and various special character subtitutions. This adds
a new rust style to cplus_demangle and adds 3 helper functions
rust_demangle, rust_demangle_sym and rust_is_mangled.

rust-demangle.c was written by David. Mark did the code formatting to
GNU style and integration into the gcc/libiberty build system and
testsuite.

include/ChangeLog:

2016-11-03  David Tolnay <dtolnay@gmail.com>
           Mark Wielaard  <mark@klomp.org>

       * demangle.h (DMGL_RUST): New macro.
       (DMGL_STYLE_MASK): Add DMGL_RUST.
       (demangling_styles): Add dlang_rust.
       (RUST_DEMANGLING_STYLE_STRING): New macro.
       (RUST_DEMANGLING): New macro.
       (rust_demangle): New prototype.
       (rust_is_mangled): Likewise.
       (rust_demangle_sym): Likewise.

libiberty/ChangeLog:

2016-11-03  David Tolnay <dtolnay@gmail.com>
           Mark Wielaard  <mark@klomp.org>

       * Makefile.in (CFILES): Add rust-demangle.c.
       (REQUIRED_OFILES): Add rust-demangle.o.
       * cplus-dem.c (libiberty_demanglers): Add rust_demangling case.
       (cplus_demangle): Handle RUST_DEMANGLING.
       (rust_demangle): New function.
       * rust-demangle.c: New file.
       * testsuite/Makefile.in (really-check): Add check-rust-demangle.
       (check-rust-demangle): New rule.
       * testsuite/rust-demangle-expected: New file.

1 files changed, 45 insertions, 2 deletions

diff --git a/libiberty/cplus-dem.c b/libiberty/cplus-dem.c
index 3125a45..0386da5 100644
--- a/libiberty/cplus-dem.c
+++ b/libiberty/cplus-dem.c
@@ -323,6 +323,12 @@ const struct demangler_engine libiberty_demanglers[] =
   }
   ,
   {
+    RUST_DEMANGLING_STYLE_STRING,
+    rust_demangling,
+    "Rust style demangling"
+  }
+  ,
+  {
     NULL, unknown_demangling, NULL
   }
 };
@@ -874,10 +880,26 @@ cplus_demangle (const char *mangled, int options)
     work->options |= (int) current_demangling_style & DMGL_STYLE_MASK;
 
   /* The V3 ABI demangling is implemented elsewhere.  */
-  if (GNU_V3_DEMANGLING || AUTO_DEMANGLING)
+  if (GNU_V3_DEMANGLING || RUST_DEMANGLING || AUTO_DEMANGLING)
     {
       ret = cplus_demangle_v3 (mangled, work->options);
-      if (ret || GNU_V3_DEMANGLING)
+      if (GNU_V3_DEMANGLING)
+	return ret;
+
+      if (ret)
+	{
+	  /* Rust symbols are GNU_V3 mangled plus some extra subtitutions.
+	     The subtitutions are always smaller, so do in place changes.  */
+	  if (rust_is_mangled (ret))
+	    rust_demangle_sym (ret);
+	  else if (RUST_DEMANGLING)
+	    {
+	      free (ret);
+	      ret = NULL;
+	    }
+	}
+
+      if (ret || RUST_DEMANGLING)
 	return ret;
     }
 
@@ -903,6 +925,27 @@ cplus_demangle (const char *mangled, int options)
   return (ret);
 }
 
+char *
+rust_demangle (const char *mangled, int options)
+{
+  /* Rust symbols are GNU_V3 mangled plus some extra subtitutions.  */
+  char *ret = cplus_demangle_v3 (mangled, options);
+
+  /* The Rust subtitutions are always smaller, so do in place changes.  */
+  if (ret != NULL)
+    {
+      if (rust_is_mangled (ret))
+	rust_demangle_sym (ret);
+      else
+	{
+	  free (ret);
+	  ret = NULL;
+	}
+    }
+
+  return ret;
+}
+
 /* Demangle ada names.  The encoding is documented in gcc/ada/exp_dbug.ads.  */
 
 char *