Merge branch 'main' into feat/printer-agent-impl

CMakeLists.txt

@@ -362,6 +362,22 @@ if (MSVC)
     if (SLIC3R_MSVC_COMPILE_PARALLEL AND CMAKE_GENERATOR MATCHES "Visual Studio")
            add_compile_options(/MP)
     endif ()
+
+    # Parse lambdas the way the standard says, as clang and GCC already do. Without it
+    # MSVC keeps its legacy lambda processor under /std:c++17 and rejects reading a
+    # constexpr constant inside a lambda that does not capture it (C3493), which no
+    # other compiler requires. Implied by /std:c++20 and /permissive-, so it is only
+    # needed while we are on C++17. clang-cl is conforming already and does not take
+    # the flag. Requires VS2019 16.8 or newer.
+    if (NOT IS_CLANG_CL)
+        # cl.exe only warns (D9002) about an unknown /Zc: option, so without this the
+        # flag would be dropped and the first lambda reading a constexpr constant would
+        # fail with C3493 far from the cause.
+        if (MSVC_VERSION LESS 1928)
+            message(FATAL_ERROR "Visual Studio 2019 16.8 (MSVC 19.28) or newer is required; detected MSVC ${MSVC_VERSION}.")
+        endif ()
+        add_compile_options(/Zc:lambda)
+    endif ()
     # /bigobj (Increase Number of Sections in .Obj file)
     # error C3859: virtual memory range for PCH exceeded; please recompile with a command line option of '-Zm90' or greater
     # Generate symbols at every build target, even for the release.