c++: Fix ANNOTATE_EXPR instantiation [PR114409]

The following testcase ICEs starting with the r14-4229 PR111529
change which moved ANNOTATE_EXPR handling from tsubst_expr to
tsubst_copy_and_build.
ANNOTATE_EXPR is only allowed in the IL to wrap a loop condition,
and the loop condition of while/for loops can be a COMPOUND_EXPR
with DECL_EXPR in the first operand and the corresponding VAR_DECL
in the second, as created by finish_cond
      else if (!empty_expr_stmt_p (cond))
        expr = build2 (COMPOUND_EXPR, TREE_TYPE (expr), cond, expr);
Since then Patrick reworked the instantiation, so that we have now
tsubst_stmt and tsubst_expr and ANNOTATE_EXPR ended up in the latter,
while only tsubst_stmt can handle DECL_EXPR.

Now, the reason why the while/for loops with variable declaration
in the condition works in templates without the pragmas (i.e. without
ANNOTATE_EXPR) is that both the FOR_STMT and WHILE_STMT handling uses
RECUR aka tsubst_stmt in handling of the *_COND operand:
    case FOR_STMT:
      stmt = begin_for_stmt (NULL_TREE, NULL_TREE);
      RECUR (FOR_INIT_STMT (t));
      finish_init_stmt (stmt);
      tmp = RECUR (FOR_COND (t));
      finish_for_cond (tmp, stmt, false, 0, false);
and
    case WHILE_STMT:
      stmt = begin_while_stmt ();
      tmp = RECUR (WHILE_COND (t));
      finish_while_stmt_cond (tmp, stmt, false, 0, false);
Therefore, it will handle DECL_EXPR embedded in COMPOUND_EXPR of the
{WHILE,FOR}_COND just fine.
But if that COMPOUND_EXPR with DECL_EXPR is wrapped with one or more
ANNOTATE_EXPRs, because ANNOTATE_EXPR is now done solely in tsubst_expr
and uses RECUR there (i.e. tsubst_expr), it will ICE on DECL_EXPR in there.

This could be fixed by keeping ANNOTATE_EXPR handling in tsubst_expr but
using tsubst_stmt for the first operand, but this patch instead
moves ANNOTATE_EXPR handling to tsubst_stmt (and uses tsubst_expr for the
second/third operand).

2024-04-11  Jakub Jelinek  <jakub@redhat.com>

	PR c++/114409
	* pt.cc (tsubst_expr) <case ANNOTATE_EXPR>: Move to ...
	(tsubst_stmt) <case ANNOTATE_EXPR>: ... here.  Use tsubst_expr
	instead of RECUR for the last 2 arguments.

	* g++.dg/ext/pr114409-2.C: New test.

0 files changed, 0 insertions, 0 deletions