[PATCH] c++: build_new_1 and non-dep array size [PR111929]

[Patrick Palka <ppalka@redhat.com>]

Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look
like the right approach?

-- >8 --

This PR is another instance of NON_DEPENDENT_EXPR having acted as an
"analysis barrier" for middle-end routines, and now that it's gone we
may end up passing weird templated trees (that have a generic tree code)
to the middle-end which leads to an ICE.  In the testcase below the
non-dependent array size 'var + 42' is expressed as an ordinary
PLUS_EXPR, but whose operand types have different precisions -- long and
int respectively -- naturally because templated trees encode only the
syntactic form of an expression devoid of e.g. implicit conversions
(typically).  This type incoherency triggers a wide_int assert during
the call to size_binop in build_new_1 which requires the operand types
have the same precision.

This patch fixes this by replacing our incremental folding of 'size'
within build_new_1 with a single call to cp_fully_fold (which is a no-op
in template context) once 'size' is fully built.

	PR c++/111929

gcc/cp/ChangeLog:

	* init.cc (build_new_1): Use convert, build2, build3 instead of
	fold_convert, size_binop and fold_build3 when building 'size'.

gcc/testsuite/ChangeLog:

	* g++.dg/template/non-dependent28.C: New test.
---
 gcc/cp/init.cc                                  | 9 +++++----
 gcc/testsuite/g++.dg/template/non-dependent28.C | 6 ++++++
 2 files changed, 11 insertions(+), 4 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/template/non-dependent28.C

diff --git a/gcc/cp/init.cc b/gcc/cp/init.cc
index d48bb16c7c5..56c1b5e9f5e 100644
--- a/gcc/cp/init.cc
+++ b/gcc/cp/init.cc
@@ -3261,7 +3261,7 @@ build_new_1 (vec<tree, va_gc> **placement, tree type, tree nelts,
       max_outer_nelts = wi::udiv_trunc (max_size, inner_size);
       max_outer_nelts_tree = wide_int_to_tree (sizetype, max_outer_nelts);
 
-      size = size_binop (MULT_EXPR, size, fold_convert (sizetype, nelts));
+      size = build2 (MULT_EXPR, sizetype, size, convert (sizetype, nelts));
 
       if (TREE_CODE (cst_outer_nelts) == INTEGER_CST)
 	{
@@ -3344,7 +3344,7 @@ build_new_1 (vec<tree, va_gc> **placement, tree type, tree nelts,
       /* Use a class-specific operator new.  */
       /* If a cookie is required, add some extra space.  */
       if (array_p && TYPE_VEC_NEW_USES_COOKIE (elt_type))
-	size = size_binop (PLUS_EXPR, size, cookie_size);
+	size = build2 (PLUS_EXPR, sizetype, size, cookie_size);
       else
 	{
 	  cookie_size = NULL_TREE;
@@ -3358,8 +3358,8 @@ build_new_1 (vec<tree, va_gc> **placement, tree type, tree nelts,
       if (cxx_dialect >= cxx11 && flag_exceptions)
 	errval = throw_bad_array_new_length ();
       if (outer_nelts_check != NULL_TREE)
-	size = fold_build3 (COND_EXPR, sizetype, outer_nelts_check,
-			    size, errval);
+	size = build3 (COND_EXPR, sizetype, outer_nelts_check, size, errval);
+      size = cp_fully_fold (size);
       /* Create the argument list.  */
       vec_safe_insert (*placement, 0, size);
       /* Do name-lookup to find the appropriate operator.  */
@@ -3418,6 +3418,7 @@ build_new_1 (vec<tree, va_gc> **placement, tree type, tree nelts,
       /* If size is zero e.g. due to type having zero size, try to
 	 preserve outer_nelts for constant expression evaluation
 	 purposes.  */
+      size = cp_fully_fold (size);
       if (integer_zerop (size) && outer_nelts)
 	size = build2 (MULT_EXPR, TREE_TYPE (size), size, outer_nelts);
 
diff --git a/gcc/testsuite/g++.dg/template/non-dependent28.C b/gcc/testsuite/g++.dg/template/non-dependent28.C
new file mode 100644
index 00000000000..3e45154f61d
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/non-dependent28.C
@@ -0,0 +1,6 @@
+// PR c++/111929
+
+template<class>
+void f(long var) {
+  new int[var + 42];
+}
-- 
2.42.0.424.gceadf0f3cf