Guard generated platform extensions with V build flags

.github/workflows/historical-registry-ci.yml

@@ -81,6 +81,11 @@ jobs:
           python src/main.py -registry vulkandocs/xml/vk.xml vulkan.v
           python src/main.py -registry vulkandocs/xml/video.xml vulkan_video.v
 
+          grep -F 'pub const khr_xlib_surface_extension_name' src/vulkan.v
+          grep -F '$if vulkan_xlib ? {' src/vulkan.v
+          grep -F '#flag -DVK_USE_PLATFORM_XLIB_KHR' src/vulkan.v
+          grep -F '$if vulkan_win32 ? {' src/vulkan.v
+
           grep -F 'pub type StdVideoH264ScalingListsScalingList4x4Array' \
             src/vulkan_video.v
           if grep -E '^[[:space:]]+[A-Z][A-Za-z0-9_]*[[:space:]]+\[' \
@@ -95,6 +100,8 @@ jobs:
           ln -s "$GITHUB_WORKSPACE/published" \
             "$RUNNER_TEMP/vmodules/antono2/vulkan"
           VMODULES="$RUNNER_TEMP/vmodules" v -new-compiler -check test/main.c.v
+          VMODULES="$RUNNER_TEMP/vmodules" v -new-compiler -d vulkan_xlib \
+            -check test/main.c.v
 
   generate-and-compile:
     name: Vulkan-Docs ${{ matrix.version }}
@@ -146,6 +153,9 @@ jobs:
             --output "$VULKAN_SDK/include/volk/volk.c"
           ln -s "$GITHUB_WORKSPACE/published" "$HOME/.vmodules/antono2/vulkan"
           v -cc gcc run test
+          if [[ "$VERSION" == v1.4.335 ]]; then
+            v -d vulkan_xlib -cc gcc run test
+          fi
 
   required-checks:
     if: always()

README.md

@@ -46,6 +46,15 @@ The script refuses to switch an existing `vulkandocs` checkout if it contains
 local changes. Generated files are written to `src/vulkan.v` and
 `src/vulkan_video.v`; review their diff before committing.
 
+Platform extensions are selected with V compile flags derived from the
+registry's `<platform>` names. For example, `-d vulkan_xlib` includes the
+Xlib declarations and supplies `VK_USE_PLATFORM_XLIB_KHR` to the C compiler.
+XCB and Wayland have separate flags (`vulkan_xcb` and `vulkan_wayland`).
+The same rule applies to Android, Win32, Metal, and the other registry
+platforms. Extension name and spec-version constants remain available without
+the flag; platform types and commands require it and the platform's native
+development headers.
+
 ## Manual generation
 
 The generator imports helper modules from a `vulkandocs` checkout at the

src/vgenerator.py

@@ -336,6 +336,7 @@ def __init__(self, *args, **kwargs):
         self.feature_not_empty = False
         self.may_alias = None
         self.fixed_array_aliases = []
+        self.emitted_platform_flags = set()
 
     def beginFile(self, genOpts):
         OutputGenerator.beginFile(self, genOpts)
@@ -401,6 +402,15 @@ def endFile(self):
     def beginFeature(self, interface, emit):
         # Start processing in superclass
         OutputGenerator.beginFeature(self, interface, emit)
+        platform = interface.get('platform')
+        self.feature_platform_flag = None
+        self.feature_platform_protect = None
+        if platform:
+            platform_elem = self.registry.tree.find(f"./platforms/platform[@name='{platform}']")
+            if platform_elem is None or not platform_elem.get('protect'):
+                raise RuntimeError(f'Missing Vulkan guard for platform {platform}')
+            self.feature_platform_flag = f'vulkan_{platform}'
+            self.feature_platform_protect = platform_elem.get('protect')
         # C-specific
         # Accumulate includes, defines, types, enums, function pointer typedefs,
         # end function prototypes separately for this feature. They are only
@@ -447,8 +457,35 @@ def endFeature(self):
                     self.newline()
 
                     self.featureName = self.removeVk(self.featureName)
+                    # Extension name/version constants are useful when checking
+                    # support, even when their platform declarations are off.
+                    if self.feature_platform_flag and self.sections['define']:
+                        write('\n'.join(self.sections['define']), file=self.outFile)
+                    public_constants = []
+                    if self.feature_platform_flag:
+                        constant_prefix = f'pub const {self.featureName}_'
+                        for entry in self.sections['enum']:
+                            stripped = entry.strip()
+                            if stripped.startswith(constant_prefix) and (
+                                stripped.startswith(constant_prefix + 'spec_version') or
+                                stripped.startswith(constant_prefix + 'extension_name')
+                            ):
+                                public_constants.append(entry)
+                        if public_constants:
+                            write('\n'.join(public_constants), file=self.outFile)
+                    if self.feature_platform_flag:
+                        if self.feature_platform_flag not in self.emitted_platform_flags:
+                            write(f'$if {self.feature_platform_flag} ? {{', file=self.outFile)
+                            write(f'#flag -D{self.feature_platform_protect}', file=self.outFile)
+                            write('}', file=self.outFile)
+                            self.emitted_platform_flags.add(self.feature_platform_flag)
+                        write(f'$if {self.feature_platform_flag} ? {{', file=self.outFile)
                     for section in self.TYPE_SECTIONS:
+                        if self.feature_platform_flag and section == 'define':
+                            continue
                         contents = self.sections[section]
+                        if self.feature_platform_flag and section == 'enum':
+                            contents = [entry for entry in contents if entry not in public_constants]
                         if contents:
                             write('\n'.join(contents), file=self.outFile)
                     if self.genOpts.genFuncPointers and self.sections['commandPointer']:
@@ -475,6 +512,8 @@ def endFeature(self):
                                   file=self.outFile)
                         else:
                             self.newline()
+                    if self.feature_platform_flag:
+                        write('}', file=self.outFile)
                     if self.featureExtraProtect is not None:
                         write('#endif' +
                               self._endProtectComment(protect_str=self.featureExtraProtect),