[Sema] Put existing warning under -Wexcess-initializers

[rsandifo-arm]

Summary

I have a follow-on patch that uses an alternative wording for
this warning in some cases. This patch puts it under its own
-W option in order to avoid a regression in Misc/warning-flags.c.

[efriedma]

Should we stick ext_excess_initializers_in_char_array_initializer and ext_initializer_string_for_char_array_too_long in the same warning group?

[rsandifo-arm]

Put two other related warnings under the new option

[rsandifo-arm]

In D79244#2019027, @efriedma wrote:

Should we stick ext_excess_initializers_in_char_array_initializer and ext_initializer_string_for_char_array_too_long in the same warning group?

Yeah, agree that would be better. Done in v2.

[efriedma]

LGTM

clang/docs/DiagnosticsReference.rst

 |:warning:`warning:` |nbsp| :diagtext:`exception of type` |nbsp| :placeholder:`A` |nbsp| :diagtext:`will be caught by earlier handler`|
 +-------------------------------------------------------------------------------------------------------------------------------------+
 
 +-----------------------------------------------------------------------------------------------------------------------------+
 |:warning:`warning:` |nbsp| :placeholder:`A` |nbsp| :diagtext:`has a non-throwing exception specification but can still throw`|
 +-----------------------------------------------------------------------------------------------------------------------------+
 
 
+-Wexcess-initializers
+---------------------
+This diagnostic is enabled by default.
+
+**Diagnostic text:**
+
++-----------------------------------------------------------------+--------------------+-------------------------------+
+|:warning:`warning:` |nbsp| :diagtext:`excess elements in` |nbsp| |+------------------+| |nbsp| :diagtext:`initializer`|
+|                                                                 ||:diagtext:`array` ||                               |
+|                                                                 |+------------------+|                               |
+|                                                                 ||:diagtext:`vector`||                               |
+|                                                                 |+------------------+|                               |
+|                                                                 ||:diagtext:`scalar`||                               |
+|                                                                 |+------------------+|                               |
+|                                                                 ||:diagtext:`union` ||                               |
+|                                                                 |+------------------+|                               |
+|                                                                 ||:diagtext:`struct`||                               |
+|                                                                 |+------------------+|                               |
++-----------------------------------------------------------------+--------------------+-------------------------------+
+
++--------------------------------------------------------------------------------+
+|:warning:`warning:` |nbsp| :diagtext:`excess elements in char array initializer`|
++--------------------------------------------------------------------------------+
+
++------------------------------------------------------------------------------------+
+|:warning:`warning:` |nbsp| :diagtext:`initializer-string for char array is too long`|
++------------------------------------------------------------------------------------+
+
+
 -Wexit-time-destructors
 -----------------------
 **Diagnostic text:**
 
 +-----------------------------------------------------------------------------------+
 |:warning:`warning:` |nbsp| :diagtext:`declaration requires an exit-time destructor`|
 +-----------------------------------------------------------------------------------+
 

clang/include/clang/Basic/DiagnosticGroups.td

 def DanglingInitializerList : DiagGroup<"dangling-initializer-list">;
 def DanglingGsl : DiagGroup<"dangling-gsl">;
 def ReturnStackAddress : DiagGroup<"return-stack-address">;
 def Dangling : DiagGroup<"dangling", [DanglingField,
                                       DanglingInitializerList,
                                       DanglingGsl,
                                       ReturnStackAddress]>;
 def DistributedObjectModifiers : DiagGroup<"distributed-object-modifiers">;
+def ExcessInitializers : DiagGroup<"excess-initializers">;
 def ExpansionToDefined : DiagGroup<"expansion-to-defined">;
 def FlagEnum : DiagGroup<"flag-enum">;
 def IncrementBool : DiagGroup<"increment-bool", [DeprecatedIncrementBool]>;
 def InfiniteRecursion : DiagGroup<"infinite-recursion">;
 def PureVirtualCallFromCtorDtor: DiagGroup<"call-to-pure-virtual-from-ctor-dtor">;
 def GNUImaginaryConstant : DiagGroup<"gnu-imaginary-constant">;
 def IgnoredQualifiers : DiagGroup<"ignored-qualifiers">;
 def : DiagGroup<"import">;

clang/include/clang/Basic/DiagnosticSemaKinds.td

def err_block_extern_cant_init : Error<
   "'extern' variable cannot have an initializer">;
 def warn_extern_init : Warning<"'extern' variable has an initializer">,
   InGroup<DiagGroup<"extern-initializer">>;
 def err_variable_object_no_init : Error<
   "variable-sized object may not be initialized">;
 def err_excess_initializers : Error<
   "excess elements in %select{array|vector|scalar|union|struct}0 initializer">;
 def ext_excess_initializers : ExtWarn<
-  "excess elements in %select{array|vector|scalar|union|struct}0 initializer">;
+  "excess elements in %select{array|vector|scalar|union|struct}0 initializer">,
+  InGroup<ExcessInitializers>;
 def err_excess_initializers_in_char_array_initializer : Error<
   "excess elements in char array initializer">;
 def ext_excess_initializers_in_char_array_initializer : ExtWarn<
-  "excess elements in char array initializer">;
+  "excess elements in char array initializer">,
+  InGroup<ExcessInitializers>;
 def err_initializer_string_for_char_array_too_long : Error<
   "initializer-string for char array is too long">;
 def ext_initializer_string_for_char_array_too_long : ExtWarn<
-  "initializer-string for char array is too long">;
+  "initializer-string for char array is too long">,
+  InGroup<ExcessInitializers>;
 def warn_missing_field_initializers : Warning<
   "missing field %0 initializer">,
   InGroup<MissingFieldInitializers>, DefaultIgnore;
 def warn_braces_around_scalar_init : Warning<
   "braces around scalar initializer">, InGroup<DiagGroup<"braced-scalar-init">>;
 def ext_many_braces_around_scalar_init : ExtWarn<
   "too many braces around scalar initializer">,
   InGroup<DiagGroup<"many-braces-around-scalar-init">>, SFINAEFailure;

clang/test/Misc/warning-flags.c

(2) It prevents us adding new warnings to Clang that have no -W flag.  All
     new warnings should have -W flags.
 
     If you add a new warning without a flag, this test will fail.  To fix
     this test, simply add a warning group to that warning.
 
 
 The list of warnings below should NEVER grow.  It should gradually shrink to 0.
 
-CHECK: Warnings without flags (75):
-CHECK-NEXT:   ext_excess_initializers
-CHECK-NEXT:   ext_excess_initializers_in_char_array_initializer
+CHECK: Warnings without flags (72):
 CHECK-NEXT:   ext_expected_semi_decl_list
 CHECK-NEXT:   ext_explicit_specialization_storage_class
-CHECK-NEXT:   ext_initializer_string_for_char_array_too_long
 CHECK-NEXT:   ext_missing_declspec
 CHECK-NEXT:   ext_missing_whitespace_after_macro_name
 CHECK-NEXT:   ext_new_paren_array_nonconst
 CHECK-NEXT:   ext_plain_complex
 CHECK-NEXT:   ext_template_arg_extra_parens
 CHECK-NEXT:   ext_typecheck_cond_incompatible_operands
 CHECK-NEXT:   ext_typecheck_ordered_comparison_of_pointer_integer
 CHECK-NEXT:   ext_using_undefined_std

clang/test/Sema/array-init.c

void testTypedef()
   int b_sizecheck[(sizeof(b) / sizeof(int)) == 3? 1 : -1];
 }
 
 static char const xx[] = "test";
 int xx_sizecheck[(sizeof(xx) / sizeof(char)) == 5? 1 : -1];
 static char const yy[5] = "test";
 static char const zz[3] = "test"; // expected-warning{{initializer-string for char array is too long}}
 
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wexcess-initializers"
+static char const zz_quiet[3] = "test";
+#pragma clang diagnostic pop
+
 void charArrays() {
   static char const test[] = "test";
   int test_sizecheck[(sizeof(test) / sizeof(char)) == 5? 1 : -1];
   static char const test2[] = { "weird stuff" };
   static char const test3[] = { "test", "excess stuff" }; // expected-warning{{excess elements in char array initializer}}
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wexcess-initializers"
+  static char const test3_quiet[] = {"test", "excess stuff"};
+#pragma clang diagnostic pop
 
   char* cp[] = { "Hello" };
 
   char c[] = { "Hello" };
   int l[sizeof(c) == 6 ? 1 : -1];
   
   int i[] = { "Hello "}; // expected-warning{{incompatible pointer to integer conversion initializing 'int' with an expression of type 'char [7]'}}
   char c2[] = { "Hello", "Good bye" }; //expected-warning{{excess elements in char array initializer}}

clang/test/Sema/init.c

struct foo2 {
    uintptr_t a;
 };
 
 struct foo2 bar2[] = {
    { (intptr_t)bbb }
 };
 
 struct foo2 bar3 = { 1, 2 }; // expected-warning{{excess elements in struct initializer}}
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wexcess-initializers"
+struct foo2 bar3_silent = {1, 2};
+#pragma clang diagnostic pop
 
 int* ptest1 = __builtin_choose_expr(1, (int*)0, (int*)0);
 
 typedef int32_t ivector4 __attribute((vector_size(16)));
 ivector4 vtest1 = 1 ? (ivector4){1} : (ivector4){1};
 ivector4 vtest2 = __builtin_choose_expr(1, (ivector4){1}, (ivector4){1});
 
 uintptr_t ptrasintadd1 = (uintptr_t)&a - 4;