What is ac_nonexistent.h?

Question

Examining a buildlog from a failed build, what does the following error mean,

fatal error: ac_nonexistent.h: No such file or directory #include <ac_nonexistent.h>

Here is some context.

configure:6614: $? = 0
configure:6627: result: none needed
configure:6648: checking how to run the C preprocessor
configure:6679: gcc -E -Wdate-time -D_FORTIFY_SOURCE=2 conftest.c
configure:6679: $? = 0
configure:6693: gcc -E -Wdate-time -D_FORTIFY_SOURCE=2 conftest.c
conftest.c:11:28: fatal error: ac_nonexistent.h: No such file or directory
 #include <ac_nonexistent.h>
                            ^
compilation terminated.
configure:6693: $? = 1
configure: failed program was:
| /* confdefs.h */

What is ac_nonexistent.h? What should I do when I encounter this error?

Solution

That’s a sanity check, to ensure that the configuration script is correctly able to determine whether a header file is present or not: it asks the compiler to use a non-existant header, and checks that the compiler (correctly) fails.

Note that your build goes on after that “error”... To figure out the cause of a build failure, you should generally work up from the end of the build log. In this instance the important part of the log is

configure:47489: checking for the Wayland protocols
configure:47492: $PKG_CONFIG --exists --print-errors "wayland-protocols >= 1.4"
Package wayland-protocols was not found in the pkg-config search path.
Perhaps you should add the directory containing `wayland-protocols.pc' to the PKG_CONFIG_PATH environment variable
No package 'wayland-protocols' found

Comments

[ipatch]

hello old friend