Add branch for location of cxx flags

Summary: This adds a branch on where the cxx flags are read from. There is no observable behavior change. It is an intermediate step that prepares the code to read the cxx flags from the CxxToolchain. Reading from the CxxToolchain will be added in a later diff.

Reviewed By: JakobDegen

Differential Revision: D69610559

fbshipit-source-id: f981fdf47a61941704c4ba9a79b1d6c9130cd5bf

prelude/ide_integrations/visual_studio/constants.bxl

@@ -18,6 +18,7 @@ BY_MODES = "ByModes"
 
 CXXFLAGS = "cxxflags"
 CXXPPFLAGS = "cxxppflags"
+FLAGS_LOCATION = "flags_location"
 LDFLAGS = "ldflags"
 TOOLSET = "toolset"
 LANGUAGE_STANDARD = "language_standard"

prelude/ide_integrations/visual_studio/gen_mode_configs.bxl

@@ -5,7 +5,7 @@
 # License, Version 2.0 found in the LICENSE-APACHE file in the root directory
 # of this source tree.
 
-load("constants.bxl", "ANDROID", "CLANG", "CXXFLAGS", "CXXPPFLAGS", "LANGUAGE_STANDARD", "LDFLAGS", "TOOLSET", "VS2019", "VS2022")
+load("constants.bxl", "ANDROID", "CLANG", "CXXFLAGS", "CXXPPFLAGS", "FLAGS_LOCATION", "LANGUAGE_STANDARD", "LDFLAGS", "TOOLSET", "VS2019", "VS2022")
 load("flags_parser_utils.bxl", "get_compiler_settings_from_flags", "get_linker_settings_from_flags")
 load("get_compiler_settings.bxl", "gen_compiler_settings")
 load("get_linker_settings.bxl", "gen_linker_settings")
@@ -20,30 +20,42 @@ ANDROID_CXXPPFLAGS = read_root_config("fbcode-platform-cxx#platform010-clang", "
 ANDROID_CXXFLAGS = read_root_config("fbcode-platform-cxx#platform010-clang", "cxxflags") or ""
 ANDROID_LDFLAGS = read_root_config("fbcode-platform-cxx#platform010-clang", "ldflags") or ""
 
+# Simple enum used to determine where flags come from.
+_FlagsLocation = enum(
+    # Flags come from the dict itsself
+    "dict",
+    # Flags come from the CxxToolchain
+    "CxxToolchain",  # @unused, Will use in a future change.
+)
+
 # @unsorted-dict-items
 LANGUAGE_STANDARD_AND_TOOLSET_MAP = {
     ANDROID: {
+        FLAGS_LOCATION: _FlagsLocation("dict"),
         CXXFLAGS: ANDROID_CXXFLAGS,
         CXXPPFLAGS: ANDROID_CXXPPFLAGS,
         LDFLAGS: ANDROID_LDFLAGS,
         LANGUAGE_STANDARD: None,
         TOOLSET: "Clang_5_0",
     },
     CLANG: {
+        FLAGS_LOCATION: _FlagsLocation("dict"),
         CXXFLAGS: STD_CXXFLAGS,
         CXXPPFLAGS: STD_CXXPPFLAGS,
         LDFLAGS: STD_LDFLAGS,
         LANGUAGE_STANDARD: "stdcpp20",
         TOOLSET: "ClangCL",
     },
     VS2019: {
+        FLAGS_LOCATION: _FlagsLocation("dict"),
         CXXFLAGS: STD_CXXFLAGS,
         CXXPPFLAGS: STD_CXXPPFLAGS,
         LDFLAGS: STD_LDFLAGS,
         LANGUAGE_STANDARD: "stdcpp17",
         TOOLSET: "v142",
     },
     VS2022: {
+        FLAGS_LOCATION: _FlagsLocation("dict"),
         CXXFLAGS: STD_CXXFLAGS,
         CXXPPFLAGS: STD_CXXPPFLAGS,
         LDFLAGS: STD_LDFLAGS,
@@ -68,17 +80,20 @@ def _remove_flags_with_macros(flags: list) -> list:
     flags = [item for item in flags if "$(" not in item and ")" not in item]
     return dedupe_by_value(flags)
 
-def _get_compiler_settings(platform: str) -> dict:
-    cxxppflags = LANGUAGE_STANDARD_AND_TOOLSET_MAP[platform][CXXPPFLAGS]
-    cxxflags = LANGUAGE_STANDARD_AND_TOOLSET_MAP[platform][CXXFLAGS]
-    compiler_flags = cxxppflags.split(" ") + cxxflags.split(" ")
+# Simple record type that holds flags read from the `cxx_toolchain`.
+_CxxToolchainFlags = record(
+    cxxflags = list[str],
+    cxxppflags = list[str],
+    ldflags = list[str],
+)
+
+def _get_compiler_settings(cxx_toolchain_flags: _CxxToolchainFlags) -> dict:
+    compiler_flags = cxx_toolchain_flags.cxxppflags + cxx_toolchain_flags.cxxflags
     compiler_flags = _remove_flags_with_macros(compiler_flags)
     return get_compiler_settings_from_flags(compiler_flags)
 
-def _get_linker_settings(platform: str, buck_root: str) -> dict:
-    ldflags = LANGUAGE_STANDARD_AND_TOOLSET_MAP[platform][LDFLAGS]
-    linker_flags = ldflags.split(" ")
-    linker_flags = _remove_flags_with_macros(linker_flags)
+def _get_linker_settings(cxx_toolchain_flags: _CxxToolchainFlags, buck_root: str) -> dict:
+    linker_flags = _remove_flags_with_macros(cxx_toolchain_flags.ldflags)
     return get_linker_settings_from_flags(linker_flags, buck_root)
 
 def _get_provider_output_path(provider, bxl_ctx):
@@ -97,8 +112,24 @@ def _get_path(target: str, bxl_ctx):
 def _main(bxl_ctx):
     platform = _get_platform(bxl_ctx.cli_args.vs_version_year)
 
-    compiler_settings = _get_compiler_settings(platform)
-    linker_settings = _get_linker_settings(platform, bxl_ctx.root())
+    flags_location = LANGUAGE_STANDARD_AND_TOOLSET_MAP[platform][FLAGS_LOCATION]
+
+    if flags_location == _FlagsLocation("dict"):
+        cxxppflags = LANGUAGE_STANDARD_AND_TOOLSET_MAP[platform][CXXPPFLAGS].split(" ")
+        cxxflags = LANGUAGE_STANDARD_AND_TOOLSET_MAP[platform][CXXFLAGS].split(" ")
+        ldflags = LANGUAGE_STANDARD_AND_TOOLSET_MAP[platform][LDFLAGS].split(" ")
+        cxx_toolchain_flags = _CxxToolchainFlags(
+            cxxflags = cxxflags,
+            cxxppflags = cxxppflags,
+            ldflags = ldflags,
+        )
+    elif flags_location == _FlagsLocation("CxxToolchain"):
+        fail("Not Implemented Yet flags_location '%s' in platform '%s'" % (flags_location, platform))
+    else:
+        fail("Unknown flags_location '%s' in platform '%s'" % (flags_location, platform))
+
+    compiler_settings = _get_compiler_settings(cxx_toolchain_flags)
+    linker_settings = _get_linker_settings(cxx_toolchain_flags, bxl_ctx.root())
     platform_toolset = LANGUAGE_STANDARD_AND_TOOLSET_MAP[platform][TOOLSET]
 
     # Set default language standard if not specified