Patchwork C++ PATCH for c++/55223 (ICE with lambda in default argument scope)

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Submitter Jason Merrill
Date Feb. 14, 2013, 10:37 p.m.
Message ID <511D670D.6020307@redhat.com>
Download mbox | patch
Permalink /patch/220536/
State New
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Comments

Jason Merrill - Feb. 14, 2013, 10:37 p.m.
In this PR, when we go to substitute into LAMBDA_EXPR_EXTRA_SCOPE, we 
look for a local specialization of the parameter 'f', but there isn't 
one because we aren't in a function body.  For this case, unlike uses in 
a trailing-return-type, we really need to look up the parameter in the 
function parameter list in order to get the right mangling.

While I was looking at this I noticed that the names weren't demangling, 
which turned out to be bugs in both the mangler and demangler, which 
I've also fixed.

Tested x86_64-pc-linux-gnu, applying to trunk.

Patch

commit 687e8c127536a8c208431d1786319ea6efda8637
Author: Jason Merrill <jason@redhat.com>
Date:   Thu Feb 14 10:31:38 2013 -0500

    	PR c++/55223
    gcc/cp/
    	* pt.c (tsubst_copy_and_build) [LAMBDA_EXPR]: Fix handling of
    	default argument scope.
    	* mangle.c (write_name): Likewise.
    libiberty/
    	* cp-demangle.c (d_dump): Handle DEMANGLE_COMPONENT_DEFAULT_ARG.
    	(d_print_comp): Likewise.

diff --git a/gcc/common.opt b/gcc/common.opt
index b6592e0..3c7b415 100644
--- a/gcc/common.opt
+++ b/gcc/common.opt
@@ -785,7 +785,8 @@  Driver Undocumented
 ;    argument.
 ;    First selectable in G++ 4.7.
 ;
-; 7: The version of the ABI that treats nullptr_t as a builtin type.
+; 7: The version of the ABI that treats nullptr_t as a builtin type and
+;    corrects the mangling of lambdas in default argument scope.
 ;    First selectable in G++ 4.8.
 ; Additional positive integers will be assigned as new versions of
 ; the ABI become the default version of the ABI.
diff --git a/gcc/cp/mangle.c b/gcc/cp/mangle.c
index f6b3443..a48d476 100644
--- a/gcc/cp/mangle.c
+++ b/gcc/cp/mangle.c
@@ -802,7 +802,10 @@  write_name (tree decl, const int ignore_local_scope)
   if (context == NULL
       || context == global_namespace
       || DECL_NAMESPACE_STD_P (context)
-      || (ignore_local_scope && TREE_CODE (context) == FUNCTION_DECL))
+      || (ignore_local_scope
+	  && (TREE_CODE (context) == FUNCTION_DECL
+	      || (abi_version_at_least (7)
+		  && TREE_CODE (context) == PARM_DECL))))
     {
       tree template_info;
       /* Is this a template instance?  */
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index bd44fde..aa868a4 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -14444,8 +14444,20 @@  tsubst_copy_and_build (tree t,
 	   than build a new one.  */
 	tree scope = LAMBDA_EXPR_EXTRA_SCOPE (t);
 	if (scope && TREE_CODE (scope) == FUNCTION_DECL)
-	  scope = tsubst (LAMBDA_EXPR_EXTRA_SCOPE (t), args,
-			  complain, in_decl);
+	  scope = tsubst (scope, args, complain, in_decl);
+	else if (scope && TREE_CODE (scope) == PARM_DECL)
+	  {
+	    /* Look up the parameter we want directly, as tsubst_copy
+	       doesn't do what we need.  */
+	    tree fn = tsubst (DECL_CONTEXT (scope), args, complain, in_decl);
+	    tree parm = FUNCTION_FIRST_USER_PARM (fn);
+	    while (DECL_PARM_INDEX (parm) != DECL_PARM_INDEX (scope))
+	      parm = DECL_CHAIN (parm);
+	    scope = parm;
+	    /* FIXME Work around the parm not having DECL_CONTEXT set.  */
+	    if (DECL_CONTEXT (scope) == NULL_TREE)
+	      DECL_CONTEXT (scope) = fn;
+	  }
 	else
 	  scope = RECUR (scope);
 	LAMBDA_EXPR_EXTRA_SCOPE (r) = scope;
diff --git a/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-defarg3.C b/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-defarg3.C
new file mode 100644
index 0000000..f02fb29
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-defarg3.C
@@ -0,0 +1,18 @@ 
+// PR c++/55223
+// { dg-options "-std=c++11 -fabi-version=0" }
+// { dg-final { scan-assembler "_ZN8functionC1IZN1CIiE4testES_Ed_UliE_EET_" } }
+
+struct function
+{
+  template <class U> function(U u) { }
+};
+
+template<typename T> struct C
+{
+  static T test(function f = [](int i){return i;}) { }
+};
+
+int main()
+{
+  C<int>::test();
+}
diff --git a/libiberty/cp-demangle.c b/libiberty/cp-demangle.c
index 913d4bf..39be031 100644
--- a/libiberty/cp-demangle.c
+++ b/libiberty/cp-demangle.c
@@ -707,6 +707,14 @@  d_dump (struct demangle_component *dc, int indent)
     case DEMANGLE_COMPONENT_TLS_WRAPPER:
       printf ("tls wrapper function\n");
       break;
+    case DEMANGLE_COMPONENT_DEFAULT_ARG:
+      printf ("default argument %d\n", dc->u.s_unary_num.num);
+      d_dump (dc->u.s_unary_num.sub, indent+2);
+      return;
+    case DEMANGLE_COMPONENT_LAMBDA:
+      printf ("lambda %d\n", dc->u.s_unary_num.num);
+      d_dump (dc->u.s_unary_num.sub, indent+2);
+      return;
     }
 
   d_dump (d_left (dc), indent + 2);
@@ -3168,6 +3176,7 @@  d_expr_primary (struct d_info *di)
 
 /* <local-name> ::= Z <(function) encoding> E <(entity) name> [<discriminator>]
                 ::= Z <(function) encoding> E s [<discriminator>]
+                ::= Z <(function) encoding> E d [<parameter> number>] _ <entity name>
 */
 
 static struct demangle_component *
@@ -3869,7 +3878,17 @@  d_print_comp (struct d_print_info *dpi, int options,
 	d_append_string (dpi, "::");
       else
 	d_append_char (dpi, '.');
-      d_print_comp (dpi, options, d_right (dc));
+      {
+	struct demangle_component *local_name = d_right (dc);
+	if (local_name->type == DEMANGLE_COMPONENT_DEFAULT_ARG)
+	  {
+	    d_append_string (dpi, "{default arg#");
+	    d_append_num (dpi, local_name->u.s_unary_num.num + 1);
+	    d_append_string (dpi, "}::");
+	    local_name = local_name->u.s_unary_num.sub;
+	  }
+	d_print_comp (dpi, options, local_name);
+      }
       return;
 
     case DEMANGLE_COMPONENT_TYPED_NAME:
diff --git a/libiberty/testsuite/demangle-expected b/libiberty/testsuite/demangle-expected
index 5b41b03..17eacaa 100644
--- a/libiberty/testsuite/demangle-expected
+++ b/libiberty/testsuite/demangle-expected
@@ -3951,6 +3951,9 @@  S::f(int, int)::{default arg#2}::{lambda()#2}::operator()() const
 _ZNK1SIiE1xMUlvE1_clEv
 S<int>::x::{lambda()#3}::operator()() const
 --format=gnu-v3
+_ZN8functionC1IZN1CIiE4testES_Ed_UliE_EET_
+function::function<C<int>::test(function)::{default arg#1}::{lambda(int)#1}>(C<int>::test(function)::{default arg#1}::{lambda(int)#1})
+--format=gnu-v3
 _Z1fN1SUt_E
 f(S::{unnamed type#1})
 --format=gnu-v3