Implement $Cxx.omitSchemas annotation

c++/src/capnp/c++.capnp

@@ -24,3 +24,13 @@ $namespace("capnp::annotations");
 
 annotation namespace(file): Text;
 annotation name(field, enumerant, struct, enum, interface, method, param, group, union): Text;
+
+annotation omitSchemas(file): Void;
+# Requests that the generated code does not embed the types' schemas.
+# This means you will not be able to use <capnp/schema.h> or <capnp/dynamic.h> APIs with this type.
+# By extension, that means you will not be able to stringify messages nor use the JSON codec.
+# However, the generated code will be somewhat smaller and will not include easily-extractable
+# type information, which may be important in some use cases.
+#
+# All files that import your file will also be required to set this option if they are used to
+# generate C++ code.

c++/src/capnp/c++.capnp.c++

@@ -64,5 +64,35 @@ const ::capnp::_::RawSchema s_f264a779fef191ce = {
   0, 0, nullptr, nullptr, nullptr, { &s_f264a779fef191ce, nullptr, nullptr, 0, 0, nullptr }
 };
 #endif  // !CAPNP_LITE
+static const ::capnp::_::AlignedData<21> b_e17e871ab8a5deab = {
+  {   0,   0,   0,   0,   5,   0,   6,   0,
+    171, 222, 165, 184,  26, 135, 126, 225,
+     16,   0,   0,   0,   5,   0,   1,   0,
+    129,  78,  48, 184, 123, 125, 248, 189,
+      0,   0,   0,   0,   0,   0,   0,   0,
+      0,   0,   0,   0,   0,   0,   0,   0,
+     21,   0,   0,   0, 226,   0,   0,   0,
+     33,   0,   0,   0,   7,   0,   0,   0,
+      0,   0,   0,   0,   0,   0,   0,   0,
+     28,   0,   0,   0,   3,   0,   1,   0,
+      0,   0,   0,   0,   0,   0,   0,   0,
+      0,   0,   0,   0,   0,   0,   0,   0,
+     99,  97, 112, 110, 112,  47,  99,  43,
+     43,  46,  99,  97, 112, 110, 112,  58,
+    111, 109, 105, 116,  83,  99, 104, 101,
+    109,  97, 115,   0,   0,   0,   0,   0,
+      0,   0,   0,   0,   1,   0,   1,   0,
+      0,   0,   0,   0,   0,   0,   0,   0,
+      0,   0,   0,   0,   0,   0,   0,   0,
+      0,   0,   0,   0,   0,   0,   0,   0,
+      0,   0,   0,   0,   0,   0,   0,   0, }
+};
+::capnp::word const* const bp_e17e871ab8a5deab = b_e17e871ab8a5deab.words;
+#if !CAPNP_LITE
+const ::capnp::_::RawSchema s_e17e871ab8a5deab = {
+  0xe17e871ab8a5deab, b_e17e871ab8a5deab.words, 21, nullptr, nullptr,
+  0, 0, nullptr, nullptr, nullptr, { &s_e17e871ab8a5deab, nullptr, nullptr, 0, 0, nullptr }
+};
+#endif  // !CAPNP_LITE
 }  // namespace schemas
 }  // namespace capnp

c++/src/capnp/c++.capnp.h

@@ -18,6 +18,7 @@ namespace schemas {
 
 CAPNP_DECLARE_SCHEMA(b9c6f99ebf805f2c);
 CAPNP_DECLARE_SCHEMA(f264a779fef191ce);
+CAPNP_DECLARE_SCHEMA(e17e871ab8a5deab);
 
 }  // namespace schemas
 }  // namespace capnp

c++/src/capnp/compiler/capnpc-c++.c++

@@ -64,6 +64,7 @@ namespace {
 
 static constexpr uint64_t NAMESPACE_ANNOTATION_ID = 0xb9c6f99ebf805f2cull;
 static constexpr uint64_t NAME_ANNOTATION_ID = 0xf264a779fef191ceull;
+static constexpr uint64_t OMIT_SCHEMAS_ANNOTATION_ID = 0xe17e871ab8a5deabull;
 
 bool hasDiscriminantValue(const schema::Field::Reader& reader) {
   return reader.getDiscriminantValue() != schema::Field::NO_DISCRIMINANT;
@@ -2985,6 +2986,14 @@ private:
 
     kj::Vector<kj::ArrayPtr<const char>> namespaceParts;
     kj::String namespacePrefix;
+    bool omitSchemas = false;
+
+    for (auto annotation : node.getAnnotations()) {
+      if (annotation.getId() == OMIT_SCHEMAS_ANNOTATION_ID) {
+        omitSchemas = true;
+        break;
+      }
+    }
 
     for (auto annotation: node.getAnnotations()) {
       if (annotation.getId() == NAMESPACE_ANNOTATION_ID) {
@@ -3085,7 +3094,8 @@ private:
           "\n"
           "namespace capnp {\n"
           "namespace schemas {\n",
-          KJ_MAP(n, nodeTexts) { return kj::mv(n.capnpSchemaDefs); },
+          omitSchemas ? kj::Array<kj::StringTree>() : KJ_MAP(n, nodeTexts) { return kj::mv(n.capnpSchemaDefs); },
+          omitSchemas ? "// Schemas omitted due to $Cxx.omitSchemas\n" : "",
           "}  // namespace schemas\n"
           "}  // namespace capnp\n",
           sourceDefs.size() == 0 ? kj::strTree() : kj::strTree(

c++/src/capnp/test-import2.capnp

@@ -21,12 +21,36 @@
 
 @0xc64a3bf0338a124a;
 
+using Cxx = import "/capnp/c++.capnp";
 using Import1 = import "/capnp/schema.capnp";
 using Import2 = import "test-import.capnp";
 using Import3 = import "test.capnp";
 
+$Cxx.omitSchemas;
+
 struct TestImport2 {
   foo @0 :Import3.TestAllTypes;
   bar @1 :Import1.Node;
   baz @2 :Import2.TestImport;
 }
+
+interface TestImport2Interface {
+  testInterfaceMethod @0 () -> (result :Bool);
+}
+
+interface TestImport2ExtendingInterface extends(TestImport2Interface) {
+  testInterfaceMethodTwo @0 () -> (result :Bool);
+}
+
+enum TestImport2Enum {
+  zero @0;
+  one @1;
+  two @2;
+  three @3;
+  four @4;
+}
+
+struct TestImport2Structure {
+  enumValue @0 :TestImport2Enum;
+  anInterface @1 :TestImport2ExtendingInterface;
+}