Re: [PATCH v2] c++: fix string literal member initializer bug [PR90926]

[Jason Merrill via Gcc-patches]

On 2/3/21 6:31 AM, Tom Greenslade (thomgree) via Gcc-patches wrote:

Update of https://gcc.gnu.org/pipermail/gcc-patches/2020-December/562259.html

build_aggr_conv did not correctly handle string literal member initializers.
Extended can_convert_array to handle this case. For the additional check of
compatibility of character types, factored out code from digest_init_r into a 
new function.

Testcase added for this.

Bootstrapped/regtested on x86_64-pc-linux-gnu.

gcc/cp/ChangeLog:

 PR c++/90926
 * call.c (can_convert_array): Extend to handle all valid aggregate
 initializers of an array; including by string literals, not just by
 brace-init-list.
 (build_aggr_conv): Call can_convert_array more often, not just in
 brace-init-list case.
 * typeck2.c (character_array_from_string_literal): New function.
 (digest_init_r): call character_array_from_string_literal
 * cp-tree.h: (character_array_from_string_literal): Declare.
 * g++.dg/cpp1y/nsdmi-aggr12.C: New test.

diff --git a/gcc/cp/call.c b/gcc/cp/call.c
index 87a7af12796..b917c67204f 100644
--- a/gcc/cp/call.c
+++ b/gcc/cp/call.c
@@ -895,28 +895,40 @@ strip_standard_conversion (conversion *conv)
return conv;
  }
  
-/* Subroutine of build_aggr_conv: check whether CTOR, a braced-init-list,

-   is a valid aggregate initializer for array type ATYPE.  */
+/* Subroutine of build_aggr_conv: check whether FROM is a valid aggregate
+   initializer for array type ATYPE.  */
  
  static bool

-can_convert_array (tree atype, tree ctor, int flags, tsubst_flags_t complain)
+can_convert_array (tree atype, tree from, int flags, tsubst_flags_t complain)
  {
-  unsigned i;
tree elttype = TREE_TYPE (atype);
-  for (i = 0; i < CONSTRUCTOR_NELTS (ctor); ++i)
+  unsigned i;
+
+  if (TREE_CODE (from) == CONSTRUCTOR)
  {
-  tree val = CONSTRUCTOR_ELT (ctor, i)->value;
-  bool ok;
-  if (TREE_CODE (elttype) == ARRAY_TYPE
- && TREE_CODE (val) == CONSTRUCTOR)
-   ok = can_convert_array (elttype, val, flags, complain);
-  else
-   ok = can_convert_arg (elttype, TREE_TYPE (val), val, flags,
- complain);
-  if (!ok)
-   return false;
+  for (i = 0; i < CONSTRUCTOR_NELTS (from); ++i)
+   {
+ tree val = CONSTRUCTOR_ELT (from, i)->value;
+ bool ok;
+ if (TREE_CODE (elttype) == ARRAY_TYPE)
+   ok = can_convert_array (elttype, val, flags, complain);
+ else
+   ok = can_convert_arg (elttype, TREE_TYPE (val), val, flags,
+ complain);
+ if (!ok)
+   return false;
+   }
+  return true;
  }
-  return true;
+
+  if (char_type_p (TYPE_MAIN_VARIANT (elttype))
+  && TREE_CODE (tree_strip_any_location_wrapper (from)) == STRING_CST)
+{
+  return character_array_from_string_literal(atype, from);
+}


We generally don't wrap a single statement in { }.  And you need a space 
before the (.



+
+  /* No other valid way to aggregate initialize an array.  */
+  return false;
  }
  
  /* Helper for build_aggr_conv.  Return true if FIELD is in PSET, or if

@@ -973,8 +985,7 @@ build_aggr_conv (tree type, tree ctor, int flags, 
tsubst_flags_t complain)
  tree ftype = TREE_TYPE (idx);
  bool ok;
  
-	  if (TREE_CODE (ftype) == ARRAY_TYPE

- && TREE_CODE (val) == CONSTRUCTOR)
+ if (TREE_CODE (ftype) == ARRAY_TYPE)
ok = can_convert_array (ftype, val, flags, complain);
  else
ok = can_convert_arg (ftype, TREE_TYPE (val), val, flags,
@@ -1021,9 +1032,8 @@ build_aggr_conv (tree type, tree ctor, int flags, 
tsubst_flags_t complain)
  val = empty_ctor;
}
  
-  if (TREE_CODE (ftype) == ARRAY_TYPE

- && TREE_CODE (val) == CONSTRUCTOR)
-   ok = can_convert_array (ftype, val, flags, complain);
+  if (TREE_CODE (ftype) == ARRAY_TYPE)
+   ok = can_convert_array (ftype, val, flags, complain);
else
ok = can_convert_arg (ftype, TREE_TYPE (val), val, flags,
  complain);
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index f31319904eb..8dfc581 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -7946,6 +7946,7 @@ extern tree split_nonconstant_init(tree, 
tree);
  extern bool check_narrowing   (tree, tree, tsubst_flags_t,
 bool = false);
  extern bool ordinary_char_type_p  (tree);
+extern bool character_array_from_string_literal (tree, tree);
  extern tree digest_init   (tree, tree, 
tsubst_flags_t);
  extern tree digest_init_flags (tree, tree, int, 
tsubst_flags_t);
  extern tree digest_nsdmi_init (tree, tree, tsubst_flags_t);
diff --git a/gcc/cp/typeck2.c b/gcc/cp/typeck2.c
index 

[PATCH v2] c++: fix string literal member initializer bug [PR90926]

[Tom Greenslade (thomgree) via Gcc-patches]

Update of https://gcc.gnu.org/pipermail/gcc-patches/2020-December/562259.html

build_aggr_conv did not correctly handle string literal member initializers.
Extended can_convert_array to handle this case. For the additional check of
compatibility of character types, factored out code from digest_init_r into a 
new function.

Testcase added for this.

Bootstrapped/regtested on x86_64-pc-linux-gnu.

gcc/cp/ChangeLog:

PR c++/90926
* call.c (can_convert_array): Extend to handle all valid aggregate
initializers of an array; including by string literals, not just by
brace-init-list.
(build_aggr_conv): Call can_convert_array more often, not just in
brace-init-list case.
* typeck2.c (character_array_from_string_literal): New function.
(digest_init_r): call character_array_from_string_literal
* cp-tree.h: (character_array_from_string_literal): Declare.
* g++.dg/cpp1y/nsdmi-aggr12.C: New test.

diff --git a/gcc/cp/call.c b/gcc/cp/call.c
index 87a7af12796..b917c67204f 100644
--- a/gcc/cp/call.c
+++ b/gcc/cp/call.c
@@ -895,28 +895,40 @@ strip_standard_conversion (conversion *conv)
   return conv;
 }
 
-/* Subroutine of build_aggr_conv: check whether CTOR, a braced-init-list,
-   is a valid aggregate initializer for array type ATYPE.  */
+/* Subroutine of build_aggr_conv: check whether FROM is a valid aggregate
+   initializer for array type ATYPE.  */
 
 static bool
-can_convert_array (tree atype, tree ctor, int flags, tsubst_flags_t complain)
+can_convert_array (tree atype, tree from, int flags, tsubst_flags_t complain)
 {
-  unsigned i;
   tree elttype = TREE_TYPE (atype);
-  for (i = 0; i < CONSTRUCTOR_NELTS (ctor); ++i)
+  unsigned i;
+
+  if (TREE_CODE (from) == CONSTRUCTOR)
 {
-  tree val = CONSTRUCTOR_ELT (ctor, i)->value;
-  bool ok;
-  if (TREE_CODE (elttype) == ARRAY_TYPE
- && TREE_CODE (val) == CONSTRUCTOR)
-   ok = can_convert_array (elttype, val, flags, complain);
-  else
-   ok = can_convert_arg (elttype, TREE_TYPE (val), val, flags,
- complain);
-  if (!ok)
-   return false;
+  for (i = 0; i < CONSTRUCTOR_NELTS (from); ++i)
+   {
+ tree val = CONSTRUCTOR_ELT (from, i)->value;
+ bool ok;
+ if (TREE_CODE (elttype) == ARRAY_TYPE)
+   ok = can_convert_array (elttype, val, flags, complain);
+ else
+   ok = can_convert_arg (elttype, TREE_TYPE (val), val, flags,
+ complain);
+ if (!ok)
+   return false;
+   }
+  return true;
 }
-  return true;
+
+  if (char_type_p (TYPE_MAIN_VARIANT (elttype))
+  && TREE_CODE (tree_strip_any_location_wrapper (from)) == STRING_CST)
+{ 
+  return character_array_from_string_literal(atype, from);
+}
+
+  /* No other valid way to aggregate initialize an array.  */
+  return false;
 }
 
 /* Helper for build_aggr_conv.  Return true if FIELD is in PSET, or if
@@ -973,8 +985,7 @@ build_aggr_conv (tree type, tree ctor, int flags, 
tsubst_flags_t complain)
  tree ftype = TREE_TYPE (idx);
  bool ok;
 
- if (TREE_CODE (ftype) == ARRAY_TYPE
- && TREE_CODE (val) == CONSTRUCTOR)
+ if (TREE_CODE (ftype) == ARRAY_TYPE)
ok = can_convert_array (ftype, val, flags, complain);
  else
ok = can_convert_arg (ftype, TREE_TYPE (val), val, flags,
@@ -1021,9 +1032,8 @@ build_aggr_conv (tree type, tree ctor, int flags, 
tsubst_flags_t complain)
  val = empty_ctor;
}
 
-  if (TREE_CODE (ftype) == ARRAY_TYPE
- && TREE_CODE (val) == CONSTRUCTOR)
-   ok = can_convert_array (ftype, val, flags, complain);
+  if (TREE_CODE (ftype) == ARRAY_TYPE)
+   ok = can_convert_array (ftype, val, flags, complain); 
   else
ok = can_convert_arg (ftype, TREE_TYPE (val), val, flags,
  complain);
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index f31319904eb..8dfc581 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -7946,6 +7946,7 @@ extern tree split_nonconstant_init(tree, 
tree);
 extern bool check_narrowing(tree, tree, tsubst_flags_t,
 bool = false);
 extern bool ordinary_char_type_p   (tree);
+extern bool character_array_from_string_literal (tree, tree);
 extern tree digest_init(tree, tree, 
tsubst_flags_t);
 extern tree digest_init_flags  (tree, tree, int, 
tsubst_flags_t);
 extern tree digest_nsdmi_init  (tree, tree, tsubst_flags_t);
diff --git a/gcc/cp/typeck2.c b/gcc/cp/typeck2.c
index 9ba2897390a..8fbabeb46d9 100644
--- a/gcc/cp/typeck2.c
+++ b/gcc/cp/typeck2.c
@@ -1003,6 +1003,28 @@ ordinary_char_type_p (tree type)
  || type == unsigned_char_type_node);
 }
 
+/* Checks if