[aml-sdmmc] Remove -Wno-vla-cxx-extension.

Bug: 42085293
Change-Id: I741af89cedc1dd175a4420f3114b83d6d1d3c90c
Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1050605
Commit-Queue: HanBin Yoon <hanbinyoon@google.com>
Reviewed-by: Braden Kell <bradenkell@google.com>
Reviewed-by: Petr Hosek <phosek@google.com>
Reviewed-by: Anirudh Mathukumilli <rudymathu@google.com>

Author: hanbinyoon

build/config/BUILD.gn

@@ -842,7 +842,6 @@ config("Wno-vla-cxx-extension") {
     "//src/developer/memory/metrics/tests:*",
     "//src/devices/block/bin/gpt:*",
     "//src/devices/block/bin/iochk:*",
-    "//src/devices/block/drivers/aml-sdmmc:*",
     "//src/devices/spi/bin/spiutil:*",
     "//src/devices/usb/bin/usbctl:*",
     "//src/graphics/display/drivers/amlogic-display:*",

src/devices/block/drivers/aml-sdmmc/BUILD.bazel

@@ -38,9 +38,6 @@ fuchsia_cc_driver(
         "aml-sdmmc-export.cc",
         "aml-sdmmc-regs.h",
     ],
-    copts = [
-        "-Wno-vla-cxx-extension",
-    ],
     defines = [
         "ZX_ASSERT_LEVEL=2",
         "_ALL_SOURCE",

src/devices/block/drivers/aml-sdmmc/BUILD.gn

@@ -62,9 +62,6 @@ fuchsia_driver("aml-sdmmc-driver") {
   configs += [
     "//build/config:all_source",
     "//build/config/fuchsia:enable_zircon_asserts",
-
-    # TODO(https://fxbug.dev/42085293): delete the below and fix compiler warnings
-    "//build/config:Wno-vla-cxx-extension",
   ]
   sources = [
     "aml-sdmmc-with-banjo-export.cc",

src/devices/block/drivers/aml-sdmmc/aml-sdmmc.h

@@ -151,12 +151,11 @@ class AmlSdmmc : public fdf::DriverBase, public fdf::WireServer<fuchsia_hardware
     uint64_t results = 0;
 
     std::string ToString(const uint32_t param_max) const {
-      char string[param_max + 2];
+      std::vector<char> string(param_max + 1);
       for (uint32_t i = 0; i <= param_max; i++) {
         string[i] = (results & (1ULL << i)) ? '|' : '-';
       }
-      string[param_max + 1] = '\0';
-      return string;
+      return std::string(string.data(), string.size());
     }
   };