diff mbox series

c++: dependent array bounds completion [PR104302]

Message ID 20220203042055.488698-1-jason@redhat.com
State New
Headers show
Series c++: dependent array bounds completion [PR104302] | expand

Commit Message

Jason Merrill Feb. 3, 2022, 4:20 a.m. UTC 
The patch for PR55227 changed the minimal init-list handling in
cp_complete_array_type to a call to reshape_init, which broke on the dependent
initializer.  It occurred to me that trying to deduce the array size from a
dependent init-list is wrong in general, as we can see with the second
testcase, so let's just not.  I also limited the reshape_init call to the case
of a char array, as before the patch for 55227; that's the only case where we
want to strip a level of braces from an array.

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

	PR c++/104302

gcc/cp/ChangeLog:

	* decl.cc (maybe_deduce_size_from_array_init): Give up
	on type-dependent init.
	(cp_complete_array_type): Only call reshape_init for character
	array.

gcc/testsuite/ChangeLog:

	* g++.dg/template/array35.C: New test.
	* g++.dg/template/array36.C: New test.
---
 gcc/cp/decl.cc                          | 10 ++++++++--
 gcc/testsuite/g++.dg/template/array35.C | 11 +++++++++++
 gcc/testsuite/g++.dg/template/array36.C | 15 +++++++++++++++
 3 files changed, 34 insertions(+), 2 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/template/array35.C
 create mode 100644 gcc/testsuite/g++.dg/template/array36.C


base-commit: dc898b2ba5c50a7311bc3137f0987a7831362ed8
diff mbox series

Patch

diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
index 09eed9ceba6..7b48b56231b 100644
--- a/gcc/cp/decl.cc
+++ b/gcc/cp/decl.cc
@@ -6017,6 +6017,11 @@  maybe_deduce_size_from_array_init (tree decl, tree init)
 		return;
 	      if (!check_array_designated_initializer (ce, i))
 		failure = 1;
+	      /* If an un-designated initializer is type-dependent, we can't
+		 check brace elision yet.  */
+	      if (ce->index == NULL_TREE
+		  && type_dependent_expression_p (ce->value))
+		return;
 	    }
 	}
 
@@ -8113,7 +8118,7 @@  cp_finish_decl (tree decl, tree init, bool init_const_expr_p,
       else
 	{
 	  gcc_assert (!DECL_PRETTY_FUNCTION_P (decl));
-	  /* Deduce array size even if the initializer is dependent.  */
+	  /* Try to deduce array size.  */
 	  maybe_deduce_size_from_array_init (decl, init);
 	  /* And complain about multiple initializers.  */
 	  if (init && TREE_CODE (init) == TREE_LIST && TREE_CHAIN (init)
@@ -9570,7 +9575,8 @@  cp_complete_array_type (tree *ptype, tree initial_value, bool do_default)
       /* An array of character type can be initialized from a
 	 brace-enclosed string constant so call reshape_init to
 	 remove the optional braces from a braced string literal.  */
-      if (BRACE_ENCLOSED_INITIALIZER_P (initial_value))
+      if (char_type_p (TYPE_MAIN_VARIANT (TREE_TYPE (*ptype)))
+	  && BRACE_ENCLOSED_INITIALIZER_P (initial_value))
 	initial_value = reshape_init (*ptype, initial_value,
 				      tf_warning_or_error);
 
diff --git a/gcc/testsuite/g++.dg/template/array35.C b/gcc/testsuite/g++.dg/template/array35.C
new file mode 100644
index 00000000000..9fd02633523
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/array35.C
@@ -0,0 +1,11 @@ 
+// PR c++/104302
+
+struct ss {};
+static ss ff(void* const v);
+template <unsigned mem_size>
+void f1(void) {
+    int mem[mem_size];
+    ss StateRegs[] = {
+        ff(mem)
+    };
+}
diff --git a/gcc/testsuite/g++.dg/template/array36.C b/gcc/testsuite/g++.dg/template/array36.C
new file mode 100644
index 00000000000..1511da7020d
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/array36.C
@@ -0,0 +1,15 @@ 
+// Don't try to deduce array bounds from a dependent initializer.
+// { dg-do compile { target c++11 } }
+
+struct A { int i,j; };
+
+template <class T> void f(T t)
+{
+  A ar[] = { t, t };
+  static_assert (sizeof(ar)/sizeof(A) == 1, "");
+}
+
+int main()
+{
+  f(42);
+}