Since 5598b0bd, clang -v is used to
detect the clang version. The version number was expected to come after
the word "version". For Apple clang, this doesn't work as it has its
own versioning scheme.
The version number is now first searched after the string
"based on LLVM". This works for Apple clang before version 7, and also
for e.g. Ubuntu's clang up to version 3.7. If it's not found and the
version string contains "Apple LLVM version", clang version 3.7 is
assumed, which is the version that comes with Xcode 7. Otherwise, the
version number is still expected after the word "version", which works
for very old Apple clang versions.

Ref: https://trac.macports.org/wiki/XcodeVersionInfo
Fixes https://github.com/curl/curl/issues/1606
Closes https://github.com/curl/curl/pull/1607

... supported since 7.54.1

To reduce the memory requirement for decompress, and still do almost as
good compression as with -9e.

Pointed-out-by: Dan Fandrich

The compressed output size seems to be a tad bit smaller, but generally
xz seems more preferred these days and is used directly by for example
gentoo instead of bz2.

"Users of LZMA Utils should move to XZ Utils" =>
https://tukaani.org/lzma/

Closes #1604

... and CURLOPT_REQUEST_TARGET instead of CURLOPT_STRIP_PATH_SLASH.

This option instead provides the full "alternative" target to use in the
request, instead of extracting the path from the URL.

Test 1298 and 1299 updated accordingly.

Idea-by: Evert Pot
Suggestion: https://daniel.haxx.se/blog/2017/06/19/options-with-curl/comment-page-1/#comment-18373

Closes #1593

Declare TU-local variables static.

- switch debug and release configurations so that we get an optimized
  build with GCC 4.3+ as required by typecheck-gcc
- enable warnings-as-errors for release builds
  (which have warnings disabled)

Closes https://github.com/curl/curl/pull/1595

typecheck-gcc expected curl_socket_t instead of curl_off_t arguments
for CURLINFO_OFF_T. Detected by test1521, unfortunately only when run
locally.

Closes https://github.com/curl/curl/pull/1592

Bug: https://github.com/curl/curl/commit/73a2fcea0b4adea6ba342cd7ed1149782c214ae3#commitcomment-22655993

remote_scope_id is only used when both HAVE_SOCKADDR_IN6_SIN6_SCOPE_ID
and ENABLE_IPV6 are defined instead of only one of them.

... to enable sending "OPTIONS *" which wasn't possible previously.

This option currently only works for HTTP.

Added test cases 1298 + 1299 to verify

Fixes #1280
Closes #1462

Closes #1588

Also added return value checks to make sure no unexpected return codes
are used.

this improves symmetry with the rule above

This change introduces new alternatives for the existing six
curl_easy_getinfo() options that return sizes or speeds as doubles. The
new versions are named like the old ones but with an appended '_T':

CURLINFO_CONTENT_LENGTH_DOWNLOAD_T
CURLINFO_CONTENT_LENGTH_UPLOAD_T
CURLINFO_SIZE_DOWNLOAD_T
CURLINFO_SIZE_UPLOAD_T
CURLINFO_SPEED_DOWNLOAD_T
CURLINFO_SPEED_UPLOAD_T

Closes #1511

The list was freed incorrectly since the llist refactor of
cbae73e1. Added test 1550 to verify that it works and avoid future
regressions.

Reported-by: Pascal Terjan

Fixes #1584
Closes #1585

torture mode with test 1021 found it

After deff7de0, the build without
CURL_DISABLE_PROXY and CURL_DISABLE_HTTP was failing because of missing
includes.

With CURL_DISABLE_PROXY or CURL_DISABLE_HTTP, GCC complained about a
missing prototype for Curl_connect_free.

... also updated the CURLOPT_PREQUOTE.3 man page to mention the correct
protocol support.

Closes #1514

... as it really cannot have reached this far with config being NULL,
thus this is unnecesary and misleading.

Bug: https://news.ycombinator.com/item?id=14577585 and
https://daniel.haxx.se/blog/2017/06/17/curl-doesnt-spew-binary-anymore/comment-page-1/#comment-18356

Forwarded-to-us-by: Jakub Wilk

... unless "--output -" is used. Binary detection is done by simply
checking for a binary zero in early data.

Added test 1425 1426 to verify.

Closes #1512

The configure-based build also has this in addition to -Wall.

Closes https://github.com/curl/curl/pull/1578

It usually warns when using commas instead of semicolons or other
operators by accident.

Closes https://github.com/curl/curl/pull/1578

It usually warns when forgetting to declare TU-local variables static.

Closes https://github.com/curl/curl/pull/1578

Enable -Wdouble-promotion for both GCC and clang. It warns on implicit
promotion from float to double.

Closes https://github.com/curl/curl/pull/1578

Previously, that warning was only implicitly active in C90 mode.
Enable it unconditionally as already done for GCC.

Closes https://github.com/curl/curl/pull/1578

Regression since 5113ad04.

... and remove 'flaky' from test 1061 again

Closes #1579

... the previous code would reset the header length wrongly (since
5113ad04). This makes test 1060 reliable again.

Also: make sws send even smaller chunks of data to increase the
likeliness of this happening.

Bug: https://github.com/curl/curl/issues/1254

Closes #1546