C _BitInt incremental fixes [PR102989]

On Wed, Aug 09, 2023 at 09:17:57PM +0000, Joseph Myers wrote:
> > - _Complex _BitInt(N) isn't supported; again mainly because none of the psABIs
> >   mention how those should be passed/returned; in a limited way they are
> >   supported internally because the internal functions into which
> >   __builtin_{add,sub,mul}_overflow{,_p} is lowered return COMPLEX_TYPE as a
> >   hack to return 2 values without using references/pointers
>
> What happens when the usual arithmetic conversions are applied to
> operands, one of which is a complex integer type and the other of which is
> a wider _BitInt type?  I don't see anything in the code to disallow this
> case (which would produce an expression with a _Complex _BitInt type), or
> any testcases for it.

I've added a sorry for that case (+ return the narrower COMPLEX_TYPE).
Also added testcase to verify we don't create VECTOR_TYPEs of BITINT_TYPE
even if they have mode precision and suitable size (others were rejected
already before).

> Other testcases I think should be present (along with any corresponding
> changes needed to the code itself):
>
> * Verifying that the new integer constant suffix is rejected for C++.

Done.

> * Verifying appropriate pedwarn-if-pedantic for the new constant suffix
> for versions of C before C2x (and probably for use of _BitInt type
> specifiers before C2x as well) - along with the expected -Wc11-c2x-compat
> handling (in C2x mode) / -pedantic -Wno-c11-c2x-compat in older modes.

Done.

Here is an incremental patch which does that.

2023-09-06  Jakub Jelinek  <jakub@redhat.com>

	PR c/102989
gcc/c/
	* c-decl.cc (finish_declspecs): Emit pedwarn_c11 on _BitInt.
	* c-typeck.cc (c_common_type): Emit sorry for common type between
	_Complex integer and larger _BitInt and return the _Complex integer.
gcc/c-family/
	* c-attribs.cc (type_valid_for_vector_size): Reject vector types
	with BITINT_TYPE elements even if they have mode precision and
	suitable size.
gcc/testsuite/
	* gcc.dg/bitint-19.c: New test.
	* gcc.dg/bitint-20.c: New test.
	* gcc.dg/bitint-21.c: New test.
	* gcc.dg/bitint-22.c: New test.
	* gcc.dg/bitint-23.c: New test.
	* gcc.dg/bitint-24.c: New test.
	* gcc.dg/bitint-25.c: New test.
	* gcc.dg/bitint-26.c: New test.
	* gcc.dg/bitint-27.c: New test.
	* g++.dg/ext/bitint1.C: New test.
	* g++.dg/ext/bitint2.C: New test.
	* g++.dg/ext/bitint3.C: New test.
	* g++.dg/ext/bitint4.C: New test.
libcpp/
	* expr.cc (cpp_classify_number): Diagnose wb literal suffixes
	for -pedantic* before C2X or -Wc11-c2x-compat.

gcc/c-family/c-attribs.cc

@@ -4366,7 +4366,8 @@ type_valid_for_vector_size (tree type, tree atname, tree args,
 	  && GET_MODE_CLASS (orig_mode) != MODE_INT
 	  && !ALL_SCALAR_FIXED_POINT_MODE_P (orig_mode))
       || !tree_fits_uhwi_p (TYPE_SIZE_UNIT (type))
-      || TREE_CODE (type) == BOOLEAN_TYPE)
+      || TREE_CODE (type) == BOOLEAN_TYPE
+      || TREE_CODE (type) == BITINT_TYPE)
     {
       if (error_p)
 	error ("invalid vector type for attribute %qE", atname);

gcc/c/c-decl.cc

@@ -12934,8 +12934,15 @@ finish_declspecs (struct c_declspecs *specs)
       if (specs->u.bitint_prec == -1)
 	specs->type = integer_type_node;
       else
+	{
+	  pedwarn_c11 (specs->locations[cdw_typespec], OPT_Wpedantic,
+		       "ISO C does not support %<%s_BitInt(%d)%> before C2X",
+		       specs->unsigned_p ? "unsigned "
+		       : specs->signed_p ? "signed " : "",
+		       specs->u.bitint_prec);
 	  specs->type = build_bitint_type (specs->u.bitint_prec,
 					   specs->unsigned_p);
+	}
       break;
     default:
       gcc_unreachable ();

gcc/c/c-typeck.cc

@@ -817,6 +817,12 @@ c_common_type (tree t1, tree t2)
 	return t1;
       else if (code2 == COMPLEX_TYPE && TREE_TYPE (t2) == subtype)
 	return t2;
+      else if (TREE_CODE (subtype) == BITINT_TYPE)
+	{
+	  sorry ("%<_Complex _BitInt(%d)%> unsupported",
+		 TYPE_PRECISION (subtype));
+	  return code1 == COMPLEX_TYPE ? t1 : t2;
+	}
       else
 	return build_complex_type (subtype);
     }

gcc/testsuite/g++.dg/ext/bitint1.C

@@ -0,0 +1,9 @@
+// PR c/102989
+// { dg-do compile }
+
+_BitInt(63) a;			// { dg-error "expected" }
+unsigned _BitInt(31) b;		// { dg-error "expected" }
+int c = 21wb;			// { dg-error "invalid suffix \"wb\" on integer constant" "" { target c++98_only } }
+				// { dg-error "unable to find numeric literal operator 'operator\"\"wb'" "" { target c++11 } .-1 }
+long long d = 60594869054uwb;	// { dg-error "invalid suffix \"uwb\" on integer constant" "" { target c++98_only } }
+				// { dg-error "unable to find numeric literal operator 'operator\"\"uwb'" "" { target c++11 } .-1 }

gcc/testsuite/g++.dg/ext/bitint2.C

@@ -0,0 +1,10 @@
+// PR c/102989
+// { dg-do compile }
+// { dg-options "" }
+
+_BitInt(63) a;			// { dg-error "expected" }
+unsigned _BitInt(31) b;		// { dg-error "expected" }
+int c = 21wb;			// { dg-error "invalid suffix \"wb\" on integer constant" "" { target c++98_only } }
+				// { dg-error "unable to find numeric literal operator 'operator\"\"wb'" "" { target c++11 } .-1 }
+long long d = 60594869054uwb;	// { dg-error "invalid suffix \"uwb\" on integer constant" "" { target c++98_only } }
+				// { dg-error "unable to find numeric literal operator 'operator\"\"uwb'" "" { target c++11 } .-1 }

gcc/testsuite/g++.dg/ext/bitint3.C

@@ -0,0 +1,8 @@
+// PR c/102989
+// { dg-do compile { target c++11 } }
+
+constexpr int operator""wb (unsigned long long) { return 0; }	// { dg-warning "reserved for future standardization" }
+constexpr int operator""uwb (unsigned long long) { return 1; }	// { dg-warning "reserved for future standardization" }
+
+static_assert (-42wb == 0, "");
+static_assert (81uwb == 1, "");

gcc/testsuite/g++.dg/ext/bitint4.C

@@ -0,0 +1,9 @@
+// PR c/102989
+// { dg-do compile { target c++11 } }
+// { dg-options "" }
+
+constexpr int operator""wb (unsigned long long) { return 0; }	// { dg-warning "reserved for future standardization" }
+constexpr int operator""uwb (unsigned long long) { return 1; }	// { dg-warning "reserved for future standardization" }
+
+static_assert (-42wb == 0, "");
+static_assert (81uwb == 1, "");

gcc/testsuite/gcc.dg/bitint-19.c

@@ -0,0 +1,16 @@
+/* PR c/102989 */
+/* { dg-do compile { target bitint } } */
+/* { dg-options "-std=gnu2x" } */
+
+#define expr_has_type(e, t) _Generic (e, default : 0, t : 1)
+
+void
+foo (_Complex int ci, _Complex long long cl)
+{
+  _BitInt(__SIZEOF_INT__ * __CHAR_BIT__ - 1) bi = 0wb;
+  _BitInt(__SIZEOF_LONG_LONG__ * __CHAR_BIT__ - 1) bl = 0wb;
+  static_assert (expr_has_type (ci + bi, _Complex int));
+  static_assert (expr_has_type (cl + bl, _Complex long long));
+  static_assert (expr_has_type (bi + ci, _Complex int));
+  static_assert (expr_has_type (bl + cl, _Complex long long));
+}

gcc/testsuite/gcc.dg/bitint-20.c

@@ -0,0 +1,16 @@
+/* PR c/102989 */
+/* { dg-do compile { target bitint } } */
+/* { dg-options "-std=gnu2x" } */
+
+void
+foo (_Complex int ci, _Complex long long cl)
+{
+  _BitInt(__SIZEOF_INT__ * __CHAR_BIT__ + 1) bi = 0wb;
+  ci + bi;			/* { dg-message "unsupported" } */
+  bi + ci;			/* { dg-message "unsupported" } */
+#if __BITINT_MAXWIDTH__ >= 575
+  _BitInt(575) bw = 0wb;
+  cl + bw;			/* { dg-message "unsupported" "" { target bitint575 } } */
+  bw + cl;			/* { dg-message "unsupported" "" { target bitint575 } } */
+#endif
+}

gcc/testsuite/gcc.dg/bitint-21.c

@@ -0,0 +1,11 @@
+/* PR c/102989 */
+/* { dg-do compile { target bitint } } */
+/* { dg-options "-std=gnu2x" } */
+
+#define IB __SIZEOF_INT__ * __CHAR_BIT__
+typedef _BitInt(IB) V1 __attribute__((vector_size (sizeof (_BitInt(IB)))));		/* { dg-error "invalid vector type for attribute 'vector_size'" } */
+typedef _BitInt(IB) V2 __attribute__((vector_size (8 * sizeof (_BitInt(IB)))));		/* { dg-error "invalid vector type for attribute 'vector_size'" } */
+#if __BITINT_MAXWIDTH__ >= 575
+typedef _BitInt(575) V3 __attribute__((vector_size (sizeof (_BitInt(575)))));		/* { dg-error "invalid vector type for attribute 'vector_size'" "" { target bitint575 } } */
+typedef _BitInt(575) V3 __attribute__((vector_size (16 * sizeof (_BitInt(575)))));	/* { dg-error "invalid vector type for attribute 'vector_size'" "" { target bitint575 } } */
+#endif

gcc/testsuite/gcc.dg/bitint-22.c

@@ -0,0 +1,18 @@
+// PR c/102989
+// { dg-do compile { target bitint } }
+// { dg-options "-std=c2x -pedantic-errors" }
+
+_BitInt(63) a;
+signed _BitInt(15) b;
+unsigned _BitInt(31) c;
+int d = 21wb;
+long long e = 60594869054uwb;
+__extension__ _BitInt(63) f;
+__extension__ _BitInt(15) g;
+__extension__ unsigned _BitInt(31) h;
+int i = __extension__ 21wb;
+long long j = __extension__ 60594869054uwb;
+#if 0wb == 0
+#endif
+#if 0uwb == 0
+#endif

gcc/testsuite/gcc.dg/bitint-23.c

@@ -0,0 +1,18 @@
+// PR c/102989
+// { dg-do compile { target bitint } }
+// { dg-options "-std=c2x -pedantic-errors -Wc11-c2x-compat" }
+
+_BitInt(63) a;					/* { dg-warning "ISO C does not support '_BitInt\\\(63\\\)' before C2X" } */
+signed _BitInt(15) b;				/* { dg-warning "ISO C does not support 'signed _BitInt\\\(15\\\)' before C2X" } */
+unsigned _BitInt(31) c;				/* { dg-warning "ISO C does not support 'unsigned _BitInt\\\(31\\\)' before C2X" } */
+int d = 21wb;					/* { dg-warning "ISO C does not support literal 'wb' suffixes before C2X" } */
+long long e = 60594869054uwb;			/* { dg-warning "ISO C does not support literal 'wb' suffixes before C2X" } */
+__extension__ _BitInt(63) f;
+__extension__ _BitInt(15) g;
+__extension__ unsigned _BitInt(31) h;
+int i = __extension__ 21wb;
+long long j = __extension__ 60594869054uwb;
+#if 0wb == 0					/* { dg-warning "ISO C does not support literal 'wb' suffixes before C2X" } */
+#endif
+#if 0uwb == 0					/* { dg-warning "ISO C does not support literal 'wb' suffixes before C2X" } */
+#endif

gcc/testsuite/gcc.dg/bitint-24.c

@@ -0,0 +1,18 @@
+// PR c/102989
+// { dg-do compile { target bitint } }
+// { dg-options "-std=c11" }
+
+_BitInt(63) a;
+signed _BitInt(15) b;
+unsigned _BitInt(31) c;
+int d = 21wb;
+long long e = 60594869054uwb;
+__extension__ _BitInt(63) f;
+__extension__ _BitInt(15) g;
+__extension__ unsigned _BitInt(31) h;
+int i = __extension__ 21wb;
+long long j = __extension__ 60594869054uwb;
+#if 0wb == 0
+#endif
+#if 0uwb == 0
+#endif

gcc/testsuite/gcc.dg/bitint-25.c

@@ -0,0 +1,18 @@
+// PR c/102989
+// { dg-do compile { target bitint } }
+// { dg-options "-std=c11 -Wno-c11-c2x-compat -pedantic-errors" }
+
+_BitInt(63) a;
+signed _BitInt(15) b;
+unsigned _BitInt(31) c;
+int d = 21wb;
+long long e = 60594869054uwb;
+__extension__ _BitInt(63) f;
+__extension__ _BitInt(15) g;
+__extension__ unsigned _BitInt(31) h;
+int i = __extension__ 21wb;
+long long j = __extension__ 60594869054uwb;
+#if 0wb == 0
+#endif
+#if 0uwb == 0
+#endif

gcc/testsuite/gcc.dg/bitint-26.c

@@ -0,0 +1,18 @@
+// PR c/102989
+// { dg-do compile { target bitint } }
+// { dg-options "-std=c11 -pedantic" }
+
+_BitInt(63) a;					/* { dg-warning "ISO C does not support '_BitInt\\\(63\\\)' before C2X" } */
+signed _BitInt(15) b;				/* { dg-warning "ISO C does not support 'signed _BitInt\\\(15\\\)' before C2X" } */
+unsigned _BitInt(31) c;				/* { dg-warning "ISO C does not support 'unsigned _BitInt\\\(31\\\)' before C2X" } */
+int d = 21wb;					/* { dg-warning "ISO C does not support literal 'wb' suffixes before C2X" } */
+long long e = 60594869054uwb;			/* { dg-warning "ISO C does not support literal 'wb' suffixes before C2X" } */
+__extension__ _BitInt(63) f;
+__extension__ _BitInt(15) g;
+__extension__ unsigned _BitInt(31) h;
+int i = __extension__ 21wb;
+long long j = __extension__ 60594869054uwb;
+#if 0wb == 0					/* { dg-warning "ISO C does not support literal 'wb' suffixes before C2X" } */
+#endif
+#if 0uwb == 0					/* { dg-warning "ISO C does not support literal 'wb' suffixes before C2X" } */
+#endif

gcc/testsuite/gcc.dg/bitint-27.c

@@ -0,0 +1,18 @@
+// PR c/102989
+// { dg-do compile { target bitint } }
+// { dg-options "-std=c11 -pedantic-errors" }
+
+_BitInt(63) a;					/* { dg-error "ISO C does not support '_BitInt\\\(63\\\)' before C2X" } */
+signed _BitInt(15) b;				/* { dg-error "ISO C does not support 'signed _BitInt\\\(15\\\)' before C2X" } */
+unsigned _BitInt(31) c;				/* { dg-error "ISO C does not support 'unsigned _BitInt\\\(31\\\)' before C2X" } */
+int d = 21wb;					/* { dg-error "ISO C does not support literal 'wb' suffixes before C2X" } */
+long long e = 60594869054uwb;			/* { dg-error "ISO C does not support literal 'wb' suffixes before C2X" } */
+__extension__ _BitInt(63) f;
+__extension__ _BitInt(15) g;
+__extension__ unsigned _BitInt(31) h;
+int i = __extension__ 21wb;
+long long j = __extension__ 60594869054uwb;
+#if 0wb == 0					/* { dg-error "ISO C does not support literal 'wb' suffixes before C2X" } */
+#endif
+#if 0uwb == 0					/* { dg-error "ISO C does not support literal 'wb' suffixes before C2X" } */
+#endif

libcpp/expr.cc

@@ -856,6 +856,29 @@ cpp_classify_number (cpp_reader *pfile, const cpp_token *token,
 				 virtual_location, 0, message);
        }
 
+      if ((result & CPP_N_BITINT) != 0
+	  && CPP_OPTION (pfile, cpp_warn_c11_c2x_compat) != 0)
+	{
+	  if (CPP_OPTION (pfile, cpp_warn_c11_c2x_compat) > 0)
+	    {
+	      const char *message = N_("ISO C does not support literal "
+				       "%<wb%> suffixes before C2X");
+	      if (CPP_PEDANTIC (pfile) && !CPP_OPTION (pfile, true_false))
+		cpp_pedwarning_with_line (pfile, CPP_W_C11_C2X_COMPAT,
+					  virtual_location, 0, message);
+	      else
+		cpp_warning_with_line (pfile, CPP_W_C11_C2X_COMPAT,
+				       virtual_location, 0, message);
+	    }
+	  else if (CPP_PEDANTIC (pfile) && !CPP_OPTION (pfile, true_false))
+	    {
+	      const char *message = N_("ISO C does not support literal "
+				       "%<wb%> suffixes before C2X");
+	      cpp_error_with_line (pfile, CPP_DL_PEDWARN, virtual_location, 0,
+				   message);
+	    }
+	}
+
       result |= CPP_N_INTEGER;
     }