ACPICA: acpi_resource_irq: Replace 1-element arrays with flexible array

ACPICA commit bfdd3446e7caf795c85c70326c137023942972c5

Similar to "Replace one-element array with flexible-array", replace the
1-element array with a proper flexible array member as defined by C99.

This allows the code to operate without tripping compile-time and run-
time bounds checkers (e.g. via __builtin_object_size(), -fsanitize=bounds,
and/or -fstrict-flex-arrays=3). Note that the spec requires there be at
least one interrupt, so use a union to keep space allocated for this.

The only binary change in .text and .data sections is some rearrangement
by the compiler of acpi_dm_address_common(), but appears to be harmless.

Link: https://github.com/acpica/acpica/commit/bfdd3446
Signed-off-by: Bob Moore <[e-mail]>
Signed-off-by: Rafael J. Wysocki <[e-mail]>

drivers/acpi/acpica/amlresrc.h

···
 struct aml_resource_extended_irq {
 	AML_RESOURCE_LARGE_HEADER_COMMON u8 flags;
 	u8 interrupt_count;
-	u32 interrupts[1];
+	union {
+		u32 interrupt;
+		 ACPI_FLEX_ARRAY(u32, interrupts);
+	};
 	/* res_source_index, res_source optional fields follow */
 };
 

include/acpi/acrestyp.h

···
 	u8 shareable;
 	u8 wake_capable;
 	u8 interrupt_count;
-	u8 interrupts[1];
+	union {
+		u8 interrupt;
+		 ACPI_FLEX_ARRAY(u8, interrupts);
+	};
 };
 
 struct acpi_resource_dma {
···
 	u8 wake_capable;
 	u8 interrupt_count;
 	struct acpi_resource_source resource_source;
-	u32 interrupts[1];
+	union {
+		u32 interrupt;
+		 ACPI_FLEX_ARRAY(u32, interrupts);
+	};
 };
 
 struct acpi_resource_generic_register {