This patch addresses PR 53119 (-Wmissing-braces wrongly warns about
universal zero initializer {0}). As a result, initializations in C of
the form struct foo a = { 0 }; will not trigger warnings from
-Wmissing-braces or -Wmissing-field-initializers.
The detection for constructor_zeroinit has been changed. Instead of
examining constructor_elements, which gives false negatives, each
element is now examined as it is processed. The warning for missing
braces is then moved to pop_init_level, where it can benefit from
constructor_zeroinit.
Bootstrapped and regtested on x86_64 linux, with added test case. If
this is approved, could someone commit it for me, as I do not have
access?
S. Gilles
2014-06-01 S. Gilles <sgil...@umd.edu>
gcc/ChangeLog:
PR c/53119
c/
* c-typeck.c (push_init_level, process_init_element,
pop_init_level): Correct check for zero initialization, move
missing brace warning to respect zero initialization.
* gcc.dg/pr53119.c: New testcase.
Index: gcc/c/c-typeck.c
===================================================================
--- gcc/c/c-typeck.c (revision 211081)
+++ gcc/c/c-typeck.c (working copy)
@@ -74,9 +74,9 @@
if expr.original_code == SIZEOF_EXPR. */
tree c_last_sizeof_arg;
-/* Nonzero if we've already printed a "missing braces around initializer"
- message within this initializer. */
-static int missing_braces_mentioned;
+/* Nonzero if we might need to print a "missing braces around
+ initializer" message within this initializer. */
+static int found_missing_braces;
static int require_constant_value;
static int require_constant_elements;
@@ -6858,6 +6858,9 @@
/* 1 if this constructor is erroneous so far. */
static int constructor_erroneous;
+/* 1 if this constructor is the universal zero initializer { 0 } */
+static int constructor_zeroinit;
+
/* Structure for managing pending initializer elements, organized as an
AVL tree. */
@@ -7019,7 +7022,7 @@
constructor_stack = 0;
constructor_range_stack = 0;
- missing_braces_mentioned = 0;
+ found_missing_braces = 0;
spelling_base = 0;
spelling_size = 0;
@@ -7114,6 +7117,7 @@
constructor_type = type;
constructor_incremental = 1;
constructor_designated = 0;
+ constructor_zeroinit = 1;
designator_depth = 0;
designator_erroneous = 0;
@@ -7317,12 +7321,8 @@
set_nonincremental_init (braced_init_obstack);
}
- if (implicit == 1 && warn_missing_braces && !missing_braces_mentioned)
- {
- missing_braces_mentioned = 1;
- warning_init (input_location, OPT_Wmissing_braces,
- "missing braces around initializer");
- }
+ if (implicit == 1)
+ found_missing_braces = 1;
if (TREE_CODE (constructor_type) == RECORD_TYPE
|| TREE_CODE (constructor_type) == UNION_TYPE)
@@ -7455,6 +7455,14 @@
}
}
+ /* Warn when some structs are initialized with direct aggregation. */
+ if (!implicit && found_missing_braces && warn_missing_braces
+ && !constructor_zeroinit)
+ {
+ warning_init (input_location, OPT_Wmissing_braces,
+ "missing braces around initializer");
+ }
+
/* Warn when some struct elements are implicitly initialized to zero. */
if (warn_missing_field_initializers
&& constructor_type
@@ -7461,10 +7469,6 @@
&& TREE_CODE (constructor_type) == RECORD_TYPE
&& constructor_unfilled_fields)
{
- bool constructor_zeroinit =
- (vec_safe_length (constructor_elements) == 1
- && integer_zerop ((*constructor_elements)[0].value));
-
/* Do not warn for flexible array members or zero-length arrays. */
while (constructor_unfilled_fields
&& (!DECL_SIZE (constructor_unfilled_fields)
@@ -8594,6 +8598,11 @@
designator_depth = 0;
designator_erroneous = 0;
+ if (!implicit && value.value && !integer_zerop (value.value))
+ {
+ constructor_zeroinit = 0;
+ }
+
/* Handle superfluous braces around string cst as in
char x[] = {"foo"}; */
if (string_flag
Index: gcc/testsuite/gcc.dg/pr53119.c
===================================================================
--- gcc/testsuite/gcc.dg/pr53119.c (revision 0)
+++ gcc/testsuite/gcc.dg/pr53119.c (working copy)
@@ -0,0 +1,29 @@
+
+/* { dg-do compile } */
+
+/* { dg-options "-Wmissing-braces -Wmissing-field-initializers" } */
+
+struct a {
+ int x;
+ int y;
+};
+
+struct b {
+ struct a w;
+ struct a z;
+};
+
+int main (void)
+{
+ struct a az = { 0 };
+ struct a anz = { 1 }; /* { dg-warning "missing initializer for" } */
+
+ struct b bz = { 0 };
+ struct b bnz = { 1, 2, 3, 4 }; /* { dg-warning "missing braces" } */
+
+ struct b extra = { 0, 0 };
+
+ return 0;
+}
+
+/* { dg-excess-errors "note" } */
