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[PR,94807] Consistently name lambda fn's this pointer

Message ID 59caf942-fa42-801d-7fb4-6f0bf294c16c@acm.org
State New
Headers show
Series [PR,94807] Consistently name lambda fn's this pointer | expand

Commit Message

Nathan Sidwell May 5, 2020, 2:58 p.m. UTC 
Iain discovered that a lambda fn's this pointer arg could be named 
'this' and satisfy is_this_parameter, or be called __closure and not 
satisfy it.

Turns out the parser explicitly zaps the name to be __closure, but 
instantiation of a lambda fn doesn't.  That's just confusing.

I tried not zapping the name in the parser, but that tripped over a 
problem in constexpr.cc, which in pre-17 mode started complaining about 
use of a this pointer in an constexpr fn.  with the odd name, it never 
recognized it as a this pointer.  I could have updated that too, but the 
smaller change seemed to be telling tsubst_function_decl to zap the name 
too.  (tsubst_function_decl has to treat a lambda;s this pointer 
specially, it can't just send it to tsubst with the rest of the parms, 
as that tickles an assert inside class instantiation.)

pushed to trunk

nathan
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Patch

2020-05-05  Nathan Sidwell  <nathan@acm.org>

	PR c++/94807
	* coroutines.cc (morph_fn_to_coro): Just check for
	closure_identifier.
	* pt.c (tsubst_function_decl): Update lambda fn's this_ptr name.

diff --git i/gcc/cp/coroutines.cc w/gcc/cp/coroutines.cc
index e90d3d5a3b3..246390ec0d1 100644
--- i/gcc/cp/coroutines.cc
+++ w/gcc/cp/coroutines.cc
@@ -3736,8 +3736,7 @@  morph_fn_to_coro (tree orig, tree *resumer, tree *destroyer)
 	     closure object is named 'this' instead of '__closure'.  */
 	  if (lambda_p)
 	    {
-	      parm.lambda_cobj = parm.this_ptr
-				 || (DECL_NAME (arg) == closure_identifier);
+	      parm.lambda_cobj = DECL_NAME (arg) == closure_identifier;
 	      parm.this_ptr = false;
 	    }
 	  else
diff --git i/gcc/cp/pt.c w/gcc/cp/pt.c
index 61cb75bf801..ff8391c2093 100644
--- i/gcc/cp/pt.c
+++ w/gcc/cp/pt.c
@@ -13821,6 +13821,7 @@  tsubst_function_decl (tree t, tree args, tsubst_flags_t complain,
   if (closure)
     {
       tree tparm = build_this_parm (r, closure, type_memfn_quals (type));
+      DECL_NAME (tparm) = closure_identifier;
       DECL_CHAIN (tparm) = parms;
       parms = tparm;
     }