servo: Merge #19003 - Make test-stylo compile an empty crate on Windows without Gecko (from servo:stylo_tests_windows); r=emilio

That is, in cases where it would fail to link.

This will help make Rust CI be gated on compiling Stylo: rust-lang/rust#44603

Source-Repo: https://github.com/servo/servo
Source-Revision: 38fe9533b93e985657f99a29772bf3d3c8694822

UltraBlame original commit: 6d6d75c9f64f65ecf8c71983a29f036d477c6ed6

Author: marco-c

servo/etc/ci/buildbot_steps.yml

@@ -2254,6 +2254,13 @@ bat
 build
 -
 geckolib
+-
+mach
+.
+bat
+test
+-
+stylo
 windows
 -
 msvc

servo/tests/unit/stylo/build.rs

@@ -729,4 +729,33 @@ unwrap
 (
 )
 ;
+if
+env
+:
+:
+var_os
+(
+"
+MOZ_SRC
+"
+)
+.
+is_some
+(
+)
+{
+println
+!
+(
+"
+cargo
+:
+rustc
+-
+cfg
+=
+linking_with_gecko
+"
+)
+}
 }

servo/tests/unit/stylo/lib.rs

@@ -56,6 +56,105 @@ MPL
 .
 *
 /
+/
+/
+Disable
+this
+entire
+crate
+on
+Windows
+when
+Gecko
+symbols
+are
+not
+available
+/
+/
+as
+linking
+would
+fail
+:
+/
+/
+https
+:
+/
+/
+github
+.
+com
+/
+rust
+-
+lang
+/
+rust
+/
+pull
+/
+44603
+#
+issuecomment
+-
+338807312
+/
+/
+/
+/
+On
+Linux
+and
+OS
+X
+linking
+succeeds
+anyway
+.
+/
+/
+Presumably
+these
+symbol
+declarations
+don
+t
+need
+to
+be
+resolved
+/
+/
+as
+they
+re
+not
+used
+in
+any
+code
+called
+from
+this
+crate
+.
+#
+!
+[
+cfg
+(
+any
+(
+linking_with_gecko
+not
+(
+windows
+)
+)
+)
+]
 extern
 crate
 atomic_refcell