f0d7ed10b4 depends: Propagate only specific CLI variables to sub-makes (Carl Dong)
0a33803f1c depends: boost: Use clang toolset if clang in CXX (Carl Dong)
1ce74bcde3 depends: boost: Split target-os from toolset (Carl Dong)
2d4e480813 depends: boost: Specify toolset to bootstrap.sh (Carl Dong)
3d6603e340 depends: Propagate well-known vars into depends (Carl Dong)
Pull request description:
From: https://github.com/bitcoin/bitcoin/pull/18308#issuecomment-598301117
The following monstrosity is quite useful when invoked inside `depends`, and reviewers can use it to compare the behaviour of this change against master.
```bash
make print-{{,{host,{,{i686,x86_64,riscv64}_}linux}_}{CC,CXX},boost_{cc,cxx}}
```
It would also be helpful to make sure that setting `HOST`, `CC`, and `CXX` does the right thing. The 3 hosts I found offered good coverage were: `{x86_64,i686,riscv64}-linux-gnu`. As we special-case the `x86_64` and `i686` hosts in `depends/hosts/linux.mk`, and `riscv64` is a sanity check for a non-special-cased host.
ACKs for top commit:
hebasto:
ACK f0d7ed10b4, tested on Linux Mint 19.3 (x86_64):
practicalswift:
ACK f0d7ed10b4 -- patch looks correct
laanwj:
Code review and concept ACK f0d7ed10b4
ryanofsky:
Code review ACK f0d7ed10b4. Changes since last review: adding comment explaining check for predefined make variables, dropping freetype commit, adding commit whitelisting overrides for recursive makes
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