Linker warnings for missing function declaration

Introduction

From a user : I had missed to declare some functions. So, by mistake, I had different parameters in the definition of the function and the call(s) to the same function. My application ended up with a difficult-to-find-run-time error.

The user asked:

Why didn't the IAR ILINK Linker warn me?

Background

• The problem/risk occur when implicit declarations (no declaration in the compiling unit) are used.
• Compared to the UBROF output format (used in some IAR Embedded Workbench products), this is a limitation with the ELF format that the compiler and linker are using.
• IAR is aware of this limitation in ELF.
• There are no plans for the moment to create this kind of type check in IAR ILINK Linker.

Solution

Let the compiler find these problems, by enabling:

Project > Options > C/C++ Compiler > Language > C dialect > Require prototypes

On the compiler command line, the option to use is:

--require_prototypes

Then, create a header file with the declarations and use that wherever functions are defined or called.

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