Re: [C PATCH 1/6] c: reorganize recursive type checking

[Joseph Myers]

On Sat, 26 Aug 2023, Martin Uecker via Gcc-patches wrote:

> -static int
> +static bool
>  comp_target_types (location_t location, tree ttl, tree ttr)

The comment above this function should be updated to refer to returning 
true, not to returning 1.  And other comments on common_pointer_type and 
inside that function should be updated to refer to comp_target_types 
returning true, not nonzero.

> @@ -1395,17 +1382,13 @@ free_all_tagged_tu_seen_up_to (const struct 
> tagged_tu_seen_cache *tu_til)
>  
>  /* Return 1 if two 'struct', 'union', or 'enum' types T1 and T2 are
> compatible.  If the two types are not the same (which has been
> -   checked earlier), this can only happen when multiple translation
> -   units are being compiled.  See C99 6.2.7 paragraph 1 for the exact
> -   rules.  ENUM_AND_INT_P and DIFFERENT_TYPES_P are as in
> -   comptypes_internal.  */
> +   checked earlier).  */
>  
> -static int
> +static bool
>  tagged_types_tu_compatible_p (const_tree t1, const_tree t2,
> -   bool *enum_and_int_p, bool *different_types_p)
> +   struct comptypes_data* data)

Similarly, this comment should be updated for the new return type.  Also 
the GNU style is "struct comptypes_data *data" with space before not after 
'*'.

> @@ -1631,9 +1603,9 @@ tagged_types_tu_compatible_p (const_tree t1, const_tree 
> t2,
> Otherwise, the argument types must match.
> ENUM_AND_INT_P and DIFFERENT_TYPES_P are as in comptypes_internal.  */
>  
> -static int
> +static bool
>  function_types_compatible_p (const_tree f1, const_tree f2,
> -  bool *enum_and_int_p, bool *different_types_p)
> +  struct comptypes_data *data)

Another comment to update for a changed return type.

>  /* Check two lists of types for compatibility, returning 0 for
> -   incompatible, 1 for compatible, or 2 for compatible with
> -   warning.  ENUM_AND_INT_P and DIFFERENT_TYPES_P are as in
> -   comptypes_internal.  */
> +   incompatible, 1 for compatible.  ENUM_AND_INT_P and
> +   DIFFERENT_TYPES_P are as in comptypes_internal.  */
>  
> -static int
> +static bool
>  type_lists_compatible_p (const_tree args1, const_tree args2,
> -  bool *enum_and_int_p, bool *different_types_p)
> +  struct comptypes_data *data)

This one also needs updating to remove references to parameters that no 
longer exist.

-- 
Joseph S. Myers
jos...@codesourcery.com

[C PATCH 1/6] c: reorganize recursive type checking

[Martin Uecker via Gcc-patches]

Reorganize recursive type checking to use a structure to
store information collected during the recursion and
returned to the caller (warning_needed, enum_and_init_p,
different_types_p).

gcc/c:
* c-typeck.cc (struct comptypes_data): Add structure.
(tagged_types_tu_compatible_p,
function_types_compatible_p, type_lists_compatible_p,
comptypes_internal): Add structure to interface, change
return type to bool, and adapt calls.
(comptarget_types): Change return type too bool.
(comptypes, comptypes_check_enum_int,
comptypes_check_different_types): Adapt calls.
---
 gcc/c/c-typeck.cc | 266 --
 1 file changed, 114 insertions(+), 152 deletions(-)

diff --git a/gcc/c/c-typeck.cc b/gcc/c/c-typeck.cc
index e6ddf37d412..ed1520ed6ba 100644
--- a/gcc/c/c-typeck.cc
+++ b/gcc/c/c-typeck.cc
@@ -90,12 +90,14 @@ static bool require_constant_elements;
 static bool require_constexpr_value;
 
 static tree qualify_type (tree, tree);
-static int tagged_types_tu_compatible_p (const_tree, const_tree, bool *,
-bool *);
-static int comp_target_types (location_t, tree, tree);
-static int function_types_compatible_p (const_tree, const_tree, bool *,
-   bool *);
-static int type_lists_compatible_p (const_tree, const_tree, bool *, bool *);
+struct comptypes_data;
+static bool tagged_types_tu_compatible_p (const_tree, const_tree,
+ struct comptypes_data *);
+static bool comp_target_types (location_t, tree, tree);
+static bool function_types_compatible_p (const_tree, const_tree,
+struct comptypes_data *);
+static bool type_lists_compatible_p (const_tree, const_tree,
+struct comptypes_data *);
 static tree lookup_field (tree, tree);
 static int convert_arguments (location_t, vec, tree,
  vec *, vec *, tree,
@@ -125,7 +127,8 @@ static tree find_init_member (tree, struct obstack *);
 static void readonly_warning (tree, enum lvalue_use);
 static int lvalue_or_else (location_t, const_tree, enum lvalue_use);
 static void record_maybe_used_decl (tree);
-static int comptypes_internal (const_tree, const_tree, bool *, bool *);
+static bool comptypes_internal (const_tree, const_tree,
+   struct comptypes_data *data);
 
 /* Return true if EXP is a null pointer constant, false otherwise.  */
 
@@ -1039,6 +1042,13 @@ common_type (tree t1, tree t2)
   return c_common_type (t1, t2);
 }
 
+struct comptypes_data {
+
+  bool enum_and_int_p;
+  bool different_types_p;
+  bool warning_needed;
+};
+
 /* Return 1 if TYPE1 and TYPE2 are compatible types for assignment
or various other operations.  Return 2 if they are compatible
but a warning may be needed if you use them together.  */
@@ -1047,12 +1057,13 @@ int
 comptypes (tree type1, tree type2)
 {
   const struct tagged_tu_seen_cache * tagged_tu_seen_base1 = 
tagged_tu_seen_base;
-  int val;
 
-  val = comptypes_internal (type1, type2, NULL, NULL);
+  struct comptypes_data data = { };
+  bool ret = comptypes_internal (type1, type2, );
+
   free_all_tagged_tu_seen_up_to (tagged_tu_seen_base1);
 
-  return val;
+  return ret ? (data.warning_needed ? 2 : 1) : 0;
 }
 
 /* Like comptypes, but if it returns non-zero because enum and int are
@@ -1062,12 +1073,14 @@ int
 comptypes_check_enum_int (tree type1, tree type2, bool *enum_and_int_p)
 {
   const struct tagged_tu_seen_cache * tagged_tu_seen_base1 = 
tagged_tu_seen_base;
-  int val;
 
-  val = comptypes_internal (type1, type2, enum_and_int_p, NULL);
+  struct comptypes_data data = { };
+  bool ret = comptypes_internal (type1, type2, );
+  *enum_and_int_p = data.enum_and_int_p;
+
   free_all_tagged_tu_seen_up_to (tagged_tu_seen_base1);
 
-  return val;
+  return ret ? (data.warning_needed ? 2 : 1) : 0;
 }
 
 /* Like comptypes, but if it returns nonzero for different types, it
@@ -1078,40 +1091,40 @@ comptypes_check_different_types (tree type1, tree type2,
 bool *different_types_p)
 {
   const struct tagged_tu_seen_cache * tagged_tu_seen_base1 = 
tagged_tu_seen_base;
-  int val;
 
-  val = comptypes_internal (type1, type2, NULL, different_types_p);
+  struct comptypes_data data = { };
+  bool ret = comptypes_internal (type1, type2, );
+  *different_types_p = data.different_types_p;
+
   free_all_tagged_tu_seen_up_to (tagged_tu_seen_base1);
 
-  return val;
+  return ret ? (data.warning_needed ? 2 : 1) : 0;
 }
 
-/* Return 1 if TYPE1 and TYPE2 are compatible types for assignment
-   or various other operations.  Return 2 if they are compatible
-   but a warning may be needed if you use them together.  If
-   ENUM_AND_INT_P is not NULL, and one type is an enum and the other a
-   compatible integer type, then this sets *ENUM_AND_INT_P to true;
-   *ENUM_AND_INT_P is