INTERFACE libraries were created with the intention of collecting usage
requirements for use by other targets via `target_link_libraries`.
Therefore they were not allowed to have SOURCES and were not included in
the generated buildsystem. In practice, this has become limiting:
* Header-only libraries do have sources, they just do not compile.
Developers should be able to edit those sources (the header files)
in their IDE.
* Header-only libraries may need to generate some of their header
files via custom commands.
Some projects work around these limitations by pairing each interface
library with an `add_custom_target` that makes the header files and
custom commands appear in the generated buildsystem and in IDEs.
Lift such limitations by allowing INTERFACE libraries to have SOURCES.
For those with sources, add a corresponding build target to the
generated buildsystem.
Fixes: #19145
Since commit 3b547e2e4b (VS: Simplify logic adding source file C/C++
language flag to MSVC, 2020-05-15, v3.18.0-rc1~139^2~1) we only add a
per-source language selection flag when the source file extension does
not match the compiler's default. This approach breaks when a project
adds a target-wide `-TP` flag.
Although such projects likely did not work with non-VS generators, we
did support them before in Visual Studio generators. Add a special case
to tolerate such flags again.
Fixes: #21005
Refactoring in commit 3b547e2e4b (VS: Simplify logic adding source file
C/C++ language flag to MSVC, 2020-05-15, v3.18.0-rc1~139^2~1) failed to
account for MSVC's treatment of `.C` extensions as C. Add this special
case to the logic to restore use of `-TP` for `.C` extensions.
Fixes: #20822
VS 16.6 added a `StdOutEncoding` setting for custom commands to tell
MSBuild that the output is encoded as UTF-8. In commit bc877a7e94 (Add
support to indicate UTF-8 custom command pipe output encoding,
2020-04-08) CMake learned to add the setting in anticipation of the VS
16.6 release. However, when 16.6 was released it had a bug in the
implementation of custom tasks with StdOutEncoding enabled that was
exposed by our test suite. In commit 5058fb5401 (VS: Drop
StdOutEncoding with VS 16.6 pending investigation, 2020-05-29) we
disabled the setting pending investigation.
The problem is fixed in VS 16.7 Preview 3, so restore use of the
setting when a VS instance of at least that version is detected.
Fixes: #20769
The `StdOutEncoding` added to `.vcxproj` files since commit bc877a7e94
(Add support to indicate UTF-8 custom command pipe output encoding,
2020-04-08) breaks custom commands with symbolic outputs on VS 16.6.0.
Disable it pending further investigation and possibly a fix in VS.
Issue: #20769
Do not add a target-wide language flag. We need a flag on an individual
source file to explicitly specify the C or C++ language if and only if
the source file extension does not imply it.
It is not clear how multiple configurations should be handled here, but
using an existing configuration is at least better than the empty
configuration.
Add a `VS_PLATFORM_TOOLSET` target property to set `PlatformToolset` in
the `.vcxproj` file for specific targets. Document that this is safe
only when the named toolset uses the same underlying compiler as the
primary toolset.
Fixes: #17429
properties LINK_OPTIONS and INTERFACE_LINK_OPTIONS are propagated
to the device link step.
To control which options are selected for normal link and device link steps,
the $<DEVICE_LINK> and $<HOST_LINK> generator expressions can be used.
Fixes: #18265
Adds a flag to indicate that pipe output from a custom command should be
interpreted as UTF-8 encoded. This change does not introduce a public
way to set the flag, but generators that create internally-generated
commands know if they are calling cmake, which uses UTF-8 pipes.
MSBuild added support for interpreting output of PreBuildEvent,
PreLinkEvent, PostBuildEvent, and CustomBuildStep as UTF-8. This change
will appear in Visual Studio 16.6 Preview 3. It is opt-in, and you need
to add the StdOutEncoding tag. MSBuild treats these as property bags so
if we emit the tag for earlier versions of Visual Studio it would be
safely ignored. This change emits the StdOutEncoding tag and sets it to
UTF-8 whenever the custom command UTF-8 pipe flag is set. This fixes
globalization issues when the output from cmake contained characters
that required MSBuild to interpret as UTF-8 before displaying them.
VS_SOURCE_SETTINGS_<tool> is a list of key value pairs that get written as item
metadata for any file associated with <tool> for that target. The entire value
of VS_SOURCE_SETTINGS_<tool> is evaluated as a generator expression. VS_SETTINGS
can override settings specified in this property.
VS_SETTINGS is a list of key value pairs that get written as item
metadata for the associated non-built file. The entire value of
VS_SETTINGS is evaluated as a generator expression.
Currently properties are usually stored internally as `std::string`.
However, family of GetProperty() functions return them as `const char *` using `c_str()`.
The proposed `cmProp`, typedef'ed as `const std::string *` will expose properties
more naturally.
Since commit d4d0dd0f6a (cmLinkLineComputer: Add ComputeLinkLibs
overload with backtraces, 2019-09-13, v3.16.0-rc1~87^2~4), backtraces
have been collected by `ComputeLinkLibs` by looking back through the
link implementation libraries for one matching the text of the link line
item. This is slow in projects with long link lines.
Instead, teach `cmComputeLinkDepends` and `cmComputeLinkInformation` to
carry backtrace information explicitly along with the text of each item.
Fixes: #20322
VS 2017 version 15.8 introduced support for unity builds implemented
in part by the `$(VCTargetsPath)/Microsoft.Cpp.Unity.targets` file.
Do not enable unity builds on VS 15 versions that do not have that file.
Fixes: #20284
Extend the fix from commit 0578239d3a (VS: Tell VS 16.4 not to verify
SYMBOLIC custom command outputs, 2019-09-23, v3.15.4~2^2) to apply to
SYMBOLIC *inputs* too. This is needed when there is a chain of custom
commands that use symbolic paths for ordering.
Fixes: #20179
