Add mingw extern c for intrinsics

[mborland]

Closes: #196

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.01%. Comparing base (11f03b7) to head (e7e7f60).

Additional details and impacted files

@@           Coverage Diff            @@
##           develop     #197   +/-   ##
========================================
  Coverage    94.01%   94.01%           
========================================
  Files           66       66           
  Lines         8439     8439           
========================================
  Hits          7934     7934           
  Misses         505      505           

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[mborland]

@Flamefire What is the proper way to pass a flag to b2 with boost-ci? I added https://github.com/boostorg/charconv/pull/197/files#diff-b803fcb7f17ed9235f1e5cb1fcd2f5d3b2838429d4368ae4c57ce4436577f03fR749 but when the command is called it doesn't have the proceeding cxxflags: https://github.com/boostorg/charconv/actions/runs/9028608642/job/24809413066?pr=197#step:7:57

[Flamefire]

@Flamefire What is the proper way to pass a flag to b2 with boost-ci?

I had to look that up too as it isn't obvious: When writing the CI (shell) scripts we had to ensure compatibility with Boost repositories already in use without requiring all of them to update. Those used B2_CXXFLAGS=cxxflags=-flag which made the configs harder to read then necessary.

The detection of updated configs is done by setting B2_CI_VERSION=1 (which allows to do changes by increasing that at some point). So add BOOST_CI_VERSION: 1 to

charconv/.github/workflows/ci.yml

Lines 20 to 23 in 02c6e69

	env:
	GIT_FETCH_JOBS: 8
	NET_RETRY_COUNT: 5
	DEFAULT_BUILD_VARIANT: debug,release

, see https://github.com/boostorg/boost-ci/blob/cad342d3aafbc1d4faa995ada544c4b66bcdf4ad/.github/workflows/ci.yml#L29

[mborland]

@Flamefire What is the proper way to pass a flag to b2 with boost-ci?

I had to look that up too as it isn't obvious: When writing the CI (shell) scripts we had to ensure compatibility with Boost repositories already in use without requiring all of them to update. Those used B2_CXXFLAGS=cxxflags=-flag which made the configs harder to read then necessary.

The detection of updated configs is done by setting B2_CI_VERSION=1 (which allows to do changes by increasing that at some point). So add BOOST_CI_VERSION: 1 to

charconv/.github/workflows/ci.yml

Lines 20 to 23 in 02c6e69

	env:
	GIT_FETCH_JOBS: 8
	NET_RETRY_COUNT: 5
	DEFAULT_BUILD_VARIANT: debug,release

, see https://github.com/boostorg/boost-ci/blob/cad342d3aafbc1d4faa995ada544c4b66bcdf4ad/.github/workflows/ci.yml#L29

CI looks good with this addition. Thanks as always for the help.