CODEWITHSUNDEEP
makefileconfigureautomake
Tobias Kienzler
Tobias Kienzler

Reputation: 27413

Why does `configure` not fail while `config.log` contains errors?

In my attempt to compile GCC I noticed that while ./configure doesn't yield error messages and returns an error code of 0, there are still errors logged in config.log, which do later on cause make to fail. So, why doesn't configure fail already? Or does make modify config.log later on?

Upvotes: 1

Views: 459

Answers (1)

rra
rra

Reputation: 3887

config.log contains the output of all configure probes. Some of them are expected to fail. For example, frequently Autoconf probes for several different possible alternative implementations of particular functionality, and some of them are expected to fail depending on the characteristics of your system.

It's therefore up to the author of the Autoconf configure.ac script to explicitly fail the configure step if the results are not viable. Some people do this when writing their configure.ac and some don't. Sometimes it can be quite hard to know at configure time whether a particular set of findings are viable. There's also a reasonable argument that it's easier to diagnose problems during the build, later on, than to issue an error message from configure and make people search through config.log for the details. That's particularly the case if the problems are relatively obscure.

The short answer is that configure didn't fail because the people who wrote the configure script you're running didn't program it to fail for the specific errors that you're seeing, for one reason or another.

Upvotes: 4

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