Vs backend compiler selection (#5448)

* backends/vs: Only set platform_toolset if it isn't already set

* interpreter: set backend up after the compiler

Otherwise we won't be able to check which VS toolchain to use.

* docs/using-visual-studio: wrap lines

* docs: recommend the py launcher instead of python3 for windows

* set backend.environment when building a dummy version

* backends/vs: Add support for clang-cl with vs2017 and vs2019 backends

* backends/vs: Add support for ICL (19.x) with vs2015 and vs2017 backends

1 files changed, 12 insertions, 2 deletions

diff --git a/mesonbuild/backend/vs2019backend.py b/mesonbuild/backend/vs2019backend.py
index c6e78cb..c0ff5c3 100644
--- a/mesonbuild/backend/vs2019backend.py
+++ b/mesonbuild/backend/vs2019backend.py
@@ -22,8 +22,18 @@ class Vs2019Backend(Vs2010Backend):
     def __init__(self, build):
         super().__init__(build)
         self.name = 'vs2019'
-        self.platform_toolset = 'v142'
-        self.vs_version = '2019'
+        if self.environment is not None:
+            comps = self.environment.coredata.compilers.host
+            if comps and all(c.id == 'clang-cl' for c in comps.values()):
+                self.platform_toolset = 'llvm'
+            elif comps and all(c.id == 'intel-cl' for c in comps.values()):
+                c = list(comps.values())[0]
+                if c.version.startswith('19'):
+                    self.platform_toolset = 'Intel C++ Compiler 19.0'
+                # We don't have support for versions older than 2019 right now.
+            if not self.platform_toolset:
+                self.platform_toolset = 'v142'
+            self.vs_version = '2019'
         # WindowsSDKVersion should be set by command prompt.
         sdk_version = os.environ.get('WindowsSDKVersion', None)
         if sdk_version: