[gcc r13-567] demangler: Structured Bindings

[gcc r13-567] demangler: Structured Bindings

[Nathan Sidwell]

https://gcc.gnu.org/g:451894cadcf1210883ceefb2d69a0ed2d6a8cd8b

commit r13-567-g451894cadcf1210883ceefb2d69a0ed2d6a8cd8b
Author: Nathan Sidwell <nathan@acm.org>
Date:   Tue Mar 8 13:00:35 2022 -0800

    demangler: Structured Bindings
    
    C++ Structured bindings have a mangling that has yet to be formally
    documented.  However, it's been around for a while and shows up for
    module support.
    
            include/
            * demangle.h (enum demangle_component_type): Add
            DEMANGLE_COMPONENT_STRUCTURED_BINDING.
            libiberty/
            * cp-demangle.c (d_make_comp): Adjust.
            (d_unqualified_name): Add 'DC' support.
            (d_count_template_scopes): Adjust.
            (d_print_comp_inner): Add structured binding.
            * testsuite/demangle-expected: Add testcases.

Diff:
---
 include/demangle.h                    |  4 ++-
 libiberty/cp-demangle.c               | 49 ++++++++++++++++++++++++++++++-----
 libiberty/testsuite/demangle-expected | 10 +++++++
 3 files changed, 56 insertions(+), 7 deletions(-)

diff --git a/include/demangle.h b/include/demangle.h
index 402308f769f..44a27374d4f 100644
--- a/include/demangle.h
+++ b/include/demangle.h
@@ -449,7 +449,9 @@ enum demangle_component_type
   /* A cloned function.  */
   DEMANGLE_COMPONENT_CLONE,
   DEMANGLE_COMPONENT_NOEXCEPT,
-  DEMANGLE_COMPONENT_THROW_SPEC
+  DEMANGLE_COMPONENT_THROW_SPEC,
+
+  DEMANGLE_COMPONENT_STRUCTURED_BINDING
 };
 
 /* Types which are only used internally.  */
diff --git a/libiberty/cp-demangle.c b/libiberty/cp-demangle.c
index 6dff7d28fcf..fc618fa7383 100644
--- a/libiberty/cp-demangle.c
+++ b/libiberty/cp-demangle.c
@@ -1020,6 +1020,7 @@ d_make_comp (struct d_info *di, enum demangle_component_type type,
     case DEMANGLE_COMPONENT_NULLARY:
     case DEMANGLE_COMPONENT_TRINARY_ARG2:
     case DEMANGLE_COMPONENT_TPARM_OBJ:
+    case DEMANGLE_COMPONENT_STRUCTURED_BINDING:
       if (left == NULL)
 	return NULL;
       break;
@@ -1619,12 +1620,12 @@ d_prefix (struct d_info *di, int subst)
     }
 }
 
-/* <unqualified-name> ::= <operator-name>
-                      ::= <ctor-dtor-name>
-                      ::= <source-name>
-		      ::= <local-source-name> 
-
-    <local-source-name>	::= L <source-name> <discriminator>
+/* <unqualified-name> ::= <operator-name> [<abi-tags>]
+                      ::= <ctor-dtor-name> [<abi-tags>]
+                      ::= <source-name> [<abi-tags>]
+		      ::= <local-source-name>  [<abi-tags>]
+		      ::= DC <source-name>+ E [<abi-tags>]
+    <local-source-name>	::= L <source-name> <discriminator> [<abi-tags>]
 */
 
 static struct demangle_component *
@@ -1655,6 +1656,28 @@ d_unqualified_name (struct d_info *di)
 			       d_source_name (di));
 	}
     }
+  else if (peek == 'D' && d_peek_next_char (di) == 'C')
+    {
+      // structured binding
+      d_advance (di, 2);
+      struct demangle_component *prev = NULL;
+      do
+	{
+	  struct demangle_component *next = 
+	    d_make_comp (di, DEMANGLE_COMPONENT_STRUCTURED_BINDING,
+			 d_source_name (di), NULL);
+	  if (prev)
+	    d_right (prev) = next;
+	  else
+	    ret = next;
+	  prev = next;
+	}
+      while (prev && d_peek_char (di) != 'E');
+      if (prev)
+	d_advance (di, 1);
+      else
+	ret = NULL;
+    }
   else if (peek == 'C' || peek == 'D')
     ret = d_ctor_dtor_name (di);
   else if (peek == 'L')
@@ -4179,6 +4202,7 @@ d_count_templates_scopes (struct d_print_info *dpi,
     case DEMANGLE_COMPONENT_CHARACTER:
     case DEMANGLE_COMPONENT_NUMBER:
     case DEMANGLE_COMPONENT_UNNAMED_TYPE:
+    case DEMANGLE_COMPONENT_STRUCTURED_BINDING:
       break;
 
     case DEMANGLE_COMPONENT_TEMPLATE:
@@ -4850,6 +4874,19 @@ d_print_comp_inner (struct d_print_info *dpi, int options,
       d_append_char (dpi, ']');
       return;
 
+    case DEMANGLE_COMPONENT_STRUCTURED_BINDING:
+      d_append_char (dpi, '[');
+      for (;;)
+	{
+	  d_print_comp (dpi, options, d_left (dc));
+	  dc = d_right (dc);
+	  if (!dc)
+	    break;
+	  d_append_string (dpi, ", ");
+	}
+      d_append_char (dpi, ']');
+      return;
+
     case DEMANGLE_COMPONENT_QUAL_NAME:
     case DEMANGLE_COMPONENT_LOCAL_NAME:
       d_print_comp (dpi, options, d_left (dc));
diff --git a/libiberty/testsuite/demangle-expected b/libiberty/testsuite/demangle-expected
index de54ad73cc8..2b0b531d4bf 100644
--- a/libiberty/testsuite/demangle-expected
+++ b/libiberty/testsuite/demangle-expected
@@ -1493,3 +1493,13 @@ decltype ({parm#1}.A::x) f<A>(A)
 
 _Z2f6IP1AEDtptfp_gssr1A1BE1xET_
 decltype ({parm#1}->(::A::B::x)) f6<A*>(A*)
+
+# Structured Bindings
+_ZDC1a1bE
+[a, b]
+
+_ZNStDC1aEE
+std::[a]
+
+_ZN3NMSDC1aEE
+NMS::[a]