scripts: Guard extension prototypes by default with an additional define.

Author: rpavlik

changes/sdk/pr.251.gh.OpenXR-SDK-Source.md

@@ -0,0 +1,6 @@
+---
+- issue.174.gh.OpenXR-SDK-Source
+- issue.1554.gl
+- issue.1338.gl
+---
+Hide prototypes for extension functions unless explicitly requested by defining `XR_EXTENSION_PROTOTYPES`. These functions are not exported from the loader, so having their prototypes available is confusing and leads to link errors, etc.

specification/scripts/genxr.py

@@ -148,6 +148,8 @@ def makeGenOpts(args):
             protectFeature    = False,
             protectProto      = '#ifndef',
             protectProtoStr   = 'XR_NO_PROTOTYPES',
+            protectExtensionProto      = '#ifdef',
+            protectExtensionProtoStr   = 'XR_EXTENSION_PROTOTYPES',
             apicall           = 'XRAPI_ATTR ',
             apientry          = 'XRAPI_CALL ',
             apientryp         = 'XRAPI_PTR *',
@@ -177,6 +179,8 @@ def makeGenOpts(args):
             protectFeature    = False,
             protectProto      = '#ifndef',
             protectProtoStr   = 'XR_NO_PROTOTYPES',
+            protectExtensionProto      = '#ifdef',
+            protectExtensionProtoStr   = 'XR_EXTENSION_PROTOTYPES',
             apicall           = 'XRAPI_ATTR ',
             apientry          = 'XRAPI_CALL ',
             apientryp         = 'XRAPI_PTR *',