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, 27 insertions, 2 deletions

diff --git a/include/demangle.h b/include/demangle.h
index 12f51ca..e9551cb 100644
--- a/include/demangle.h
+++ b/include/demangle.h
@@ -63,9 +63,10 @@ extern "C" {
 #define DMGL_GNU_V3	 (1 << 14)
 #define DMGL_GNAT	 (1 << 15)
 #define DMGL_DLANG	 (1 << 16)
+#define DMGL_RUST	 (1 << 17)	/* Rust wraps GNU_V3 style mangling.  */
 
 /* If none of these are set, use 'current_demangling_style' as the default. */
-#define DMGL_STYLE_MASK (DMGL_AUTO|DMGL_GNU|DMGL_LUCID|DMGL_ARM|DMGL_HP|DMGL_EDG|DMGL_GNU_V3|DMGL_JAVA|DMGL_GNAT|DMGL_DLANG)
+#define DMGL_STYLE_MASK (DMGL_AUTO|DMGL_GNU|DMGL_LUCID|DMGL_ARM|DMGL_HP|DMGL_EDG|DMGL_GNU_V3|DMGL_JAVA|DMGL_GNAT|DMGL_DLANG|DMGL_RUST)
 
 /* Enumeration of possible demangling styles.
 
@@ -88,7 +89,8 @@ extern enum demangling_styles
   gnu_v3_demangling = DMGL_GNU_V3,
   java_demangling = DMGL_JAVA,
   gnat_demangling = DMGL_GNAT,
-  dlang_demangling = DMGL_DLANG
+  dlang_demangling = DMGL_DLANG,
+  rust_demangling = DMGL_RUST
 } current_demangling_style;
 
 /* Define string names for the various demangling styles. */
@@ -104,6 +106,7 @@ extern enum demangling_styles
 #define JAVA_DEMANGLING_STYLE_STRING          "java"
 #define GNAT_DEMANGLING_STYLE_STRING          "gnat"
 #define DLANG_DEMANGLING_STYLE_STRING         "dlang"
+#define RUST_DEMANGLING_STYLE_STRING          "rust"
 
 /* Some macros to test what demangling style is active. */
 
@@ -118,6 +121,7 @@ extern enum demangling_styles
 #define JAVA_DEMANGLING (((int) CURRENT_DEMANGLING_STYLE) & DMGL_JAVA)
 #define GNAT_DEMANGLING (((int) CURRENT_DEMANGLING_STYLE) & DMGL_GNAT)
 #define DLANG_DEMANGLING (((int) CURRENT_DEMANGLING_STYLE) & DMGL_DLANG)
+#define RUST_DEMANGLING (((int) CURRENT_DEMANGLING_STYLE) & DMGL_RUST)
 
 /* Provide information about the available demangle styles. This code is
    pulled from gdb into libiberty because it is useful to binutils also.  */
@@ -175,6 +179,27 @@ ada_demangle (const char *mangled, int options);
 extern char *
 dlang_demangle (const char *mangled, int options);
 
+/* Returns non-zero iff MANGLED is a rust mangled symbol.  MANGLED must
+   already have been demangled through cplus_demangle_v3.  If this function
+   returns non-zero then MANGLED can be demangled (in-place) using
+   RUST_DEMANGLE_SYM.  */
+extern int
+rust_is_mangled (const char *mangled);
+
+/* Demangles SYM (in-place) if RUST_IS_MANGLED returned non-zero for SYM.
+   If RUST_IS_MANGLED returned zero for SYM then RUST_DEMANGLE_SYM might
+   replace characters that cannot be demangled with '?' and might truncate
+   SYM.  After calling RUST_DEMANGLE_SYM SYM might be shorter, but never
+   larger.  */
+extern void
+rust_demangle_sym (char *sym);
+
+/* Demangles MANGLED if it was GNU_V3 and then RUST mangled, otherwise
+   returns NULL. Uses CPLUS_DEMANGLE_V3, RUST_IS_MANGLED and
+   RUST_DEMANGLE_SYM.  Returns a new string that is owned by the caller.  */
+extern char *
+rust_demangle (const char *mangled, int options);
+
 enum gnu_v3_ctor_kinds {
   gnu_v3_complete_object_ctor = 1,
   gnu_v3_base_object_ctor,