“Unresolved inclusion” error with Eclipse CDT for C standard library headers

Question

I set up CDT for eclipse and wrote a simple hello world C program:

#include 

int main(void){
    puts(\"Hello, world.\");
    return 0;
}
         


        

Answer 1

Also set ${COMMAND} to gcc on Linux

Under:

• Project
• Properties
• C/C++ General
• Preprocessor Include Paths, Macros, etc.
• Providers
• CDT GCC Built-in Compiler Settings
• Command to get compiler specs

Replace:

${COMMAND} ${FLAGS} -E -P -v -dD "${INPUTS}"

with:

gcc -std=c99 -E -P -v -dD "${INPUTS}"

If you don't do this, the Eclipse stdout shows:

Unable to find full path for "-E"

and logs under ${HOME}/eclipse-workspace/.metadata/.log show:

!ENTRY org.eclipse.cdt.core 4 0 2020-04-23 20:17:07.288
!MESSAGE Error: Cannot run program "-E": Unknown reason

because ${COMMAND} ${FLAGS} are empty, and so Eclipse tries to execute the -E that comes next.

I wonder if we can properly define the COMMAND and FLAGS variables on the settings, but I tried to add them as build variables and it didn't work.

C++ version of the question: How to solve "Unresolved inclusion: " in a C++ file in Eclipse CDT?

Tested on Eclipse 2020-03 (4.15.0), Ubuntu 19.10, and this minimal Makefile project with existing sources.