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Roger-random / ESP_8_BIT_composite

Color composite video code from ESP_8_BIT as an Arduino library
MIT License
125 stars 15 forks source link

Compiler warning: format '%s' expects argument of type 'char*', but argument 2 has type 'int' [-Wformat=] [73, 46] #24

Closed vandenzel closed 2 years ago

vandenzel commented 2 years ago

Hi,

I was trying to use this library for testing, and my compiler warns about this:

format '%s' expects argument of type 'char*', but argument 2 has type 'int' [-Wformat=] [73, 46]

https://github.com/Roger-random/ESP_8_BIT_composite/blob/001174d6b526de45c6792b26d53042dcc9f6de22/ESP_8_BIT_composite.cpp#L71-L75

The compiler could be right, as far as I know you can't use %s on an int.

Compiler: xtensa-esp32-elf-gcc (crosstool-NG crosstool-ng-1.22.0-97-gc752ad5) 5.2.0 (platformio-ide on vscode, reasonably up-to-date)

Regards, Alex.

Roger-random commented 2 years ago

I've been working in Arduino IDE and it doesn't seem to surface compiler warnings. I'll try to follow your steps to compile under PlatformIO on VSCode, and see if I see it as well.

vandenzel commented 2 years ago

It's rather obvious when you look at it: n is defined as int, and within the printf you're using %s to format it. It will compile, it will even execute, but tries to format a char * starting at address n, which is probably not what you want.

Roger-random commented 2 years ago

I understand the warning and agree with the technical issue. However, I need to see the warning first. Otherwise I wouldn't be able to verify the warning is fixed!

Roger-random commented 2 years ago

Finally figured it out: apparently format warnings are not raised by default. I had to add the following line to my platform.ini before I saw the error myself.

build_flags = -Wformat