[clang] [lldb] [Clang] Introduce OverflowBehaviorType for fine-grained overflow control (PR #148914)

[Aaron Ballman via cfe-commits]

================
@@ -0,0 +1,66 @@
+// RUN: %clang_cc1 -fsyntax-only -fexperimental-overflow-behavior-types -verify %s
+
+int __ob_wrap a;
+int __ob_trap b;
+
+const int __ob_wrap c;
+volatile int __ob_trap d;
+const volatile int __ob_wrap e;
+
+int __attribute__((overflow_behavior(wrap))) attr_style_var;
+int __ob_wrap keyword_style_var;
+
+int __ob_wrap __ob_trap conflicting_var; // expected-error{{cannot combine with previous '__ob_wrap' declaration specifier}}
+
+// Test duplicate qualifiers
+int __ob_wrap __ob_wrap duplicate_wrap; // expected-warning{{duplicate '__ob_wrap' declaration specifier}}
+int __ob_trap __ob_trap duplicate_trap; // expected-warning{{duplicate '__ob_trap' declaration specifier}}
+
+int __attribute__((overflow_behavior(wrap))) __attribute__((overflow_behavior(trap))) attr_conflict; // expected-error{{conflicting 'overflow_behavior' attributes on the same type}}
+
+// Test duplicate attributes - no warning, less problematic than duplicate decl specifiers
+int __attribute__((overflow_behavior(wrap))) __attribute__((overflow_behavior(wrap))) duplicate_attr;
+
+const volatile int __ob_wrap __ob_trap __ob_wrap complex_conflict; // expected-error{{cannot combine with previous '__ob_wrap' declaration specifier}} expected-warning{{duplicate '__ob_wrap' declaration specifier}}
+
+extern int __ob_wrap __ob_trap extern_conflict; // expected-error{{cannot combine with previous '__ob_wrap' declaration specifier}}
+static int __ob_wrap __ob_trap static_conflict; // expected-error{{cannot combine with previous '__ob_wrap' declaration specifier}}
+
+void test_storage_class(void) {
+    register int __ob_wrap __ob_trap register_conflict; // expected-error{{cannot combine with previous '__ob_wrap' declaration specifier}}
+}
+
+int __ob_wrap __ob_trap *ptr_conflict; // expected-error{{cannot combine with previous '__ob_wrap' declaration specifier}}
+int __ob_wrap __ob_trap arr_conflict[5]; // expected-error{{cannot combine with previous '__ob_wrap' declaration specifier}}
+
+int __ob_wrap __ob_trap (*func_ptr_conflict)(void); // expected-error{{cannot combine with previous '__ob_wrap' declaration specifier}}
+
+void param_test(int __ob_wrap __ob_trap param); // expected-error{{cannot combine with previous '__ob_wrap' declaration specifier}}
+
+struct conflict_struct {
+    int __ob_wrap __ob_trap member; // expected-error{{cannot combine with previous '__ob_wrap' declaration specifier}}
+    int __ob_wrap __ob_wrap dup_member; // expected-warning{{duplicate '__ob_wrap' declaration specifier}}
+};
+
+typedef int __ob_wrap __ob_trap conflict_typedef; // expected-error{{cannot combine with previous '__ob_wrap' declaration specifier}}
+typedef int __ob_wrap __ob_wrap dup_typedef; // expected-warning{{duplicate '__ob_wrap' declaration specifier}}
+
+int __ob_wrap *ptr_to_wrap;
+int __ob_trap arr[10];
+int __ob_wrap (*func_ptr)(int);
+
+void test_function(int __ob_wrap param1, int __ob_trap param2);
+
+struct test_struct {
+    int __ob_wrap member1;
+    int __ob_trap member2;
+};
+
+typedef int __ob_wrap wrap_int_t;
+typedef int __ob_trap trap_int_t;
+
+typedef float __ob_wrap float_wrap; // expected-error{{__ob_wrap specifier cannot be applied to non-integer type 'float'}}
+typedef double __ob_trap double_trap; // expected-error{{__ob_trap specifier cannot be applied to non-integer type 'double'}}
+
+struct S { int i; };
+typedef struct S __ob_wrap struct_wrap; // expected-error{{__ob_wrap specifier cannot be applied to non-integer type 'struct S'}}
----------------
AaronBallman wrote:

> Just to be clear, you're fine with the other placement for these keywords, right?
> 
> ```c
> int __ob_wrap * fine; // we point to memory whose representation is consistent with int __ob_wrap
> 
> int * __ob_wrap nope; // err!
> ```

Yup, that looks correct to me.

https://github.com/llvm/llvm-project/pull/148914