tar(1) on FreeBSD does not use standard output or input when the -f flag
is not provided. Instead, it defaults to /dev/sa0 on FreeBSD.
Make this tar invocation a bit more robust and explicitly tell tar(1) to
use standard output.
This is one of the issues discovered while porting Nix to FreeBSD. It has
been tested and committed locally to FreeBSD ports:
https://svnweb.freebsd.org/ports/head/sysutils/nix/Makefile?revision=550026&view=markup#l108
When running `nix build -L` it can be fairly hard to read the output if
the build program intentionally renders whitespace on the left. A
typical example is `g++` displaying compilation errors.
With this patch, the whitespace on the left is retained to make the log
more readable:
```
foo> no configure script, doing nothing
foo> building
foo> foobar.cc: In function 'int main()':
foo> foobar.cc:5:5: error: 'wrong_func' was not declared in this scope
foo> 5 | wrong_func(1);
foo> | ^~~~~~~~~~
error: --- Error ------------------------------------------------------------------------------------- nix
error: --- Error --- nix-daemon
builder for '/nix/store/i1q76cw6cyh91raaqg5p5isd1l2x6rx2-foo-1.0.drv' failed with exit code 1
```
std::optional had redundant checks for whether it had a value.
An object is emplaced either way so it can be dereferenced
without repeating a value check
After 0ed946aa61, max-jobs setting (-j/--max-jobs)
stopped working.
The reason was that nrLocalBuilds (which compared to maxBuildJobs to figure
out whether the limit is reached or not) is not incremented yet when tryBuild
is started; So, the solution is to move the check to tryLocalBuild.
Closes https://github.com/nixos/nix/issues/3763
Otherwise the build is cluttered with
```
/nix/store/fwpn2f7a4iqszyydw7ag61zlnp6xk5d3-glibc-2.30-dev/include/features.h:382:4: warning: #warning _FORTIFY_SOURCE requires compiling with optimization (-O) [-Wcpp]
382 | # warning _FORTIFY_SOURCE requires compiling with optimization (-O)
| ^~~~~~~
```
when building with `OPTIMIZE=0`
Rather than showing an integer as the default, instead show the boolean
referenced in the description.
The nix.conf.5 manpage used to show "default: 0", which is unnecessarily
opaque and confusing (doesn't 0 mean false, even though the default is
true?); now it properly shows that the default is true.
Maximilian Bosch