From 90b4c6f299c15317eda82be698b94952ed450b9c Mon Sep 17 00:00:00 2001
From: "Earle F. Philhower, III" <earlephilhower@yahoo.com>
Date: Thu, 24 Jun 2021 12:44:57 -0700
Subject: [PATCH] Add errors on invalid/missing function return type (#8165)

GCC 10.x seems to have a knack for crashing when a function which is declared
to return a value does not.  Add a warning, present on all builds, when this
is the case.  For more info see https://github.com/esp8266/Arduino/discussions/8160

Thanks to @hreintke and @mcspr for the tips.
---
 platform.txt              | 10 +++++-----
 tools/platformio-build.py |  1 +
 2 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/platform.txt b/platform.txt
index 88d9c82b5..cabfb151f 100644
--- a/platform.txt
+++ b/platform.txt
@@ -21,11 +21,11 @@ runtime.tools.mkdir={runtime.platform.path}/tools/mkdir.py
 runtime.tools.cp={runtime.platform.path}/tools/cp.py
 runtime.tools.eboot={runtime.platform.path}/bootloaders/eboot/eboot.elf
 
-compiler.warning_flags=-w
-compiler.warning_flags.none=-w
-compiler.warning_flags.default=
-compiler.warning_flags.more=-Wall
-compiler.warning_flags.all=-Wall -Wextra
+compiler.warning_flags=-w -Werror=return-type
+compiler.warning_flags.none=-w -Werror=return-type
+compiler.warning_flags.default=-Werror=return-type
+compiler.warning_flags.more=-Wall -Werror=return-type
+compiler.warning_flags.all=-Wall -Wextra -Werror=return-type
 
 build.lwip_lib=-llwip_gcc
 build.lwip_include=lwip/include
diff --git a/tools/platformio-build.py b/tools/platformio-build.py
index 35a88fe44..de0c019e2 100644
--- a/tools/platformio-build.py
+++ b/tools/platformio-build.py
@@ -62,6 +62,7 @@ env.Append(
         "-std=gnu17",
         "-Wpointer-arith",
         "-Wno-implicit-function-declaration",
+        "-Werror=return-type",
         "-Wl,-EL",
         "-fno-inline-functions",
         "-nostdlib"