diff --git a/VERSION b/VERSION
index 5aab7a2b62..2f668e5056 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-v2.110.0-rc.1
+v2.111.0-beta.1
diff --git a/changelog/dmd.copying-to-void-arrays.dd b/changelog/dmd.copying-to-void-arrays.dd
deleted file mode 100644
index e01cac5e2e..0000000000
--- a/changelog/dmd.copying-to-void-arrays.dd
+++ /dev/null
@@ -1,15 +0,0 @@
-Copying from `const(void)[]` to `void[]` is disallowed with `-preview=fixImmutableConv`
-
-If `const(void)[]` data contains tail `const` pointers, copying to `void[]`
-can subsequently violate `const` data:
----
-void f(int*[] a, const int*[] b)
-{
-    void[] va = a;
-    const void[] vb = b;
-    va[] = vb[]; // fills `a` with pointers to const
-    *a[0] = 0; // const data mutated
-}
----
-Copying `vb` data to `va` is no longer allowed with the
-`-preview=fixImmutableConv` switch.
diff --git a/changelog/dmd.extern-std-cpp23.dd b/changelog/dmd.extern-std-cpp23.dd
new file mode 100644
index 0000000000..5b3b2256f0
--- /dev/null
+++ b/changelog/dmd.extern-std-cpp23.dd
@@ -0,0 +1,4 @@
+The compiler now accepts `-extern-std=c++23`
+
+The compiler now accepts c++23 as a supported standard for `-extern-std=`.
+Currently this only changes the value of `__traits(getTargetInfo, "cppStd")`.
diff --git a/changelog/dmd.import-exp-hexstring.dd b/changelog/dmd.import-exp-hexstring.dd
deleted file mode 100644
index c7d7178af0..0000000000
--- a/changelog/dmd.import-exp-hexstring.dd
+++ /dev/null
@@ -1,12 +0,0 @@
-Import expressions are now treated as hex strings
-
-While [Import expressions](https://dlang.org/spec/expression.html#import_expressions) are typed as `string`, they are also used to embed binary files.
-By treating them the same as [hex strings](https://dlang.org/spec/lex.html#hex_strings), they implicitly convert to arrays of integral types.
-
----
-// Formerly, a cast was required:
-immutable ubyte[] iconImg = cast(immutable ubyte[]) import("icon.png");
-
-// Now, it implicitly converts to integral arrays:
-immutable ubyte[] iconImg = import("icon.png");
----
diff --git a/changelog/dmd.isCOMClass.dd b/changelog/dmd.isCOMClass.dd
deleted file mode 100644
index 102b773bd9..0000000000
--- a/changelog/dmd.isCOMClass.dd
+++ /dev/null
@@ -1,5 +0,0 @@
-New trait `isCOMClass` to detect if a type is a COM class
-
-A Component Object Model (COM) class inherits from a possibly user-defined interface named ``IUnknown``.
-To detect this during compilation, use the trait ``__traits(isCOMClass, Type)``.
-During runtime, use the ``TypeInfo_Class`` flag.
diff --git a/changelog/dmd.unsafe-boolean-values.dd b/changelog/dmd.unsafe-boolean-values.dd
deleted file mode 100644
index 4475bb5265..0000000000
--- a/changelog/dmd.unsafe-boolean-values.dd
+++ /dev/null
@@ -1,15 +0,0 @@
-For type `bool`, values other than 0 or 1 are not `@safe`
-
-The spec [was updated](https://dlang.org/spec/type.html#bool)
-(for 2.109) so that only 0 and 1 are
-[safe values](https://dlang.org/spec/function.html#safe-values)
-for `bool`. This means that reading a `bool` value whose underlying byte representation
-has other bits set is implementation-defined and should be avoided.
-Consequently the following are deprecated in `@safe` code:
-
-* initialization of `bool` variables with `= void` (since 2.109)
-* Reading a `bool` field from a union (since 2.109)
-* Runtime casting a dynamic array to a `bool` dynamic array type
-* Runtime casting a `bool` dynamic array to a tail mutable dynamic array type
-* Casting a pointer to a `bool` pointer type
-* Casting a `bool` pointer to a tail mutable pointer type
diff --git a/compiler/src/dmd/backend/drtlsym.d b/compiler/src/dmd/backend/drtlsym.d
index b252a7fa27..ecd6476c18 100644
--- a/compiler/src/dmd/backend/drtlsym.d
+++ b/compiler/src/dmd/backend/drtlsym.d
@@ -89,7 +89,7 @@ Symbol* getRtlsym(RTLSYM i) @trusted
         case RTLSYM.DARRAYP:                symbolz(ps,FL.func,FREGSAVED,"_d_arrayboundsp", SFLexit, t); break;
         case RTLSYM.DARRAY_SLICEP:          symbolz(ps,FL.func,FREGSAVED,"_d_arraybounds_slicep", SFLexit, t); break;
         case RTLSYM.DARRAY_INDEXP:          symbolz(ps,FL.func,FREGSAVED,"_d_arraybounds_indexp", SFLexit, t); break;
-        case RTLSYM.DINVARIANT:             symbolz(ps,FL.func,FREGSAVED,"_D9invariant12_d_invariantFC6ObjectZv", 0, tsdlib); break;
+        case RTLSYM.DINVARIANT:             symbolz(ps,FL.func,FREGSAVED,"_D2rt10invariant_12_d_invariantFC6ObjectZv", 0, tsdlib); break;
         case RTLSYM.MEMCPY:                 symbolz(ps,FL.func,FREGSAVED,"memcpy",    0, t); break;
         case RTLSYM.MEMSET8:                symbolz(ps,FL.func,FREGSAVED,"memset",    0, t); break;
         case RTLSYM.MEMSET16:               symbolz(ps,FL.func,FREGSAVED,"_memset16", 0, t); break;
diff --git a/compiler/src/dmd/cli.d b/compiler/src/dmd/cli.d
index 861d5a4f22..771f1be6d0 100644
--- a/compiler/src/dmd/cli.d
+++ b/compiler/src/dmd/cli.d
@@ -359,6 +359,8 @@ dmd -cov -unittest myprog.d
                     Sets `__traits(getTargetInfo, \"cppStd\")` to `201703`)
                 $(LI $(I c++20): Use C++20 name mangling,
                     Sets `__traits(getTargetInfo, \"cppStd\")` to `202002`)
+                $(LI $(I c++23): Use C++23 name mangling,
+                    Sets `__traits(getTargetInfo, \"cppStd\")` to `202302`)
             )",
         ),
         Option("extern-std=[h|help|?]",
@@ -1122,6 +1124,7 @@ struct CLIUsage
   =c++14                Sets `__traits(getTargetInfo, \"cppStd\")` to `201402`
   =c++17                Sets `__traits(getTargetInfo, \"cppStd\")` to `201703`
   =c++20                Sets `__traits(getTargetInfo, \"cppStd\")` to `202002`
+  =c++23                Sets `__traits(getTargetInfo, \"cppStd\")` to `202302`
 ";
 
     /// Options supported by -HC
diff --git a/compiler/src/dmd/cxxfrontend.d b/compiler/src/dmd/cxxfrontend.d
index 8c6df58d9e..b3d5942696 100644
--- a/compiler/src/dmd/cxxfrontend.d
+++ b/compiler/src/dmd/cxxfrontend.d
@@ -16,6 +16,7 @@ import dmd.astenums;
 import dmd.attrib;
 import dmd.common.outbuffer : OutBuffer;
 import dmd.dclass : ClassDeclaration;
+import dmd.declaration : TypeInfoDeclaration;
 import dmd.denum : EnumDeclaration;
 import dmd.dmodule /*: Module*/;
 import dmd.dscope : Scope;
@@ -276,6 +277,19 @@ bool fill(StructDeclaration sd, Loc loc,
     return dmd.expressionsem.fill(sd, loc, elements, ctorinit);
 }
 
+/***********************************************************
+ * func.d
+ */
+FuncDeclaration genCfunc(Parameters* fparams, Type treturn, const(char)* name, StorageClass stc = STC.none)
+{
+    return FuncDeclaration.genCfunc(fparams, treturn, name, cast(STC) stc);
+}
+
+FuncDeclaration genCfunc(Parameters* fparams, Type treturn, Identifier id, StorageClass stc = STC.none)
+{
+    return FuncDeclaration.genCfunc(fparams, treturn, id, cast(STC) stc);
+}
+
 /***********************************************************
  * funcsem.d
  */
@@ -715,6 +729,18 @@ bool builtinTypeInfo(Type t)
     return dmd.typinf.builtinTypeInfo(t);
 }
 
+Type makeNakedAssociativeArray(TypeAArray t)
+{
+    import dmd.typinf;
+    return dmd.typinf.makeNakedAssociativeArray(t);
+}
+
+TypeInfoDeclaration getTypeInfoAssocArrayDeclaration(TypeAArray t, Scope* sc)
+{
+    import dmd.typinf;
+    return dmd.typinf.getTypeInfoAssocArrayDeclaration(t, sc);
+}
+
 version (IN_LLVM)
 {
     /***********************************************************
diff --git a/compiler/src/dmd/declaration.h b/compiler/src/dmd/declaration.h
index 63fdc9b69a..c7e4552608 100644
--- a/compiler/src/dmd/declaration.h
+++ b/compiler/src/dmd/declaration.h
@@ -37,6 +37,8 @@ namespace dmd
     bool checkClosure(FuncDeclaration* fd);
     MATCH leastAsSpecialized(FuncDeclaration *f, FuncDeclaration *g, Identifiers *names);
     PURE isPure(FuncDeclaration *f);
+    FuncDeclaration *genCfunc(Parameters *args, Type *treturn, const char *name, StorageClass stc=0);
+    FuncDeclaration *genCfunc(Parameters *args, Type *treturn, Identifier *id, StorageClass stc=0);
 }
 
 //enum STC : ulong from astenums.d:
@@ -126,6 +128,10 @@ public:
     short inuse;                // used to detect cycles
     uint8_t bitFields;
 
+    LINK _linkage() const;
+    LINK _linkage(LINK v);
+    bool noUnderscore() const;
+
     const char *kind() const override;
     uinteger_t size(Loc loc) override final;
 
@@ -726,9 +732,6 @@ public:
     bool hasNestedFrameRefs();
     ParameterList getParameterList();
 
-    static FuncDeclaration *genCfunc(Parameters *args, Type *treturn, const char *name, StorageClass stc=0);
-    static FuncDeclaration *genCfunc(Parameters *args, Type *treturn, Identifier *id, StorageClass stc=0);
-
     virtual FuncDeclaration *toAliasFunc() { return this; }
     void accept(Visitor *v) override { v->visit(this); }
 };
diff --git a/compiler/src/dmd/expression.d b/compiler/src/dmd/expression.d
index ef5c0b09eb..4bf1f9f25f 100644
--- a/compiler/src/dmd/expression.d
+++ b/compiler/src/dmd/expression.d
@@ -3632,6 +3632,7 @@ extern (C++) final class CastExp : UnaExp
         if (rvalue || !e1.isLvalue())
             return false;
         return (to.ty == Tsarray && (e1.type.ty == Tvector || e1.type.ty == Tsarray)) ||
+            (to.ty == Taarray && e1.type.ty == Taarray) ||
             e1.type.mutableOf.unSharedOf().equals(to.mutableOf().unSharedOf());
     }
 
diff --git a/compiler/src/dmd/expression.h b/compiler/src/dmd/expression.h
index 64acb8d2ad..3c8d90dd7e 100644
--- a/compiler/src/dmd/expression.h
+++ b/compiler/src/dmd/expression.h
@@ -40,6 +40,7 @@ class OverloadSet;
 class StringExp;
 class InterpExp;
 class LoweredAssignExp;
+class StaticForeach;
 #ifdef IN_GCC
 typedef union tree_node Symbol;
 #else
diff --git a/compiler/src/dmd/frontend.h b/compiler/src/dmd/frontend.h
index 9e07b7236f..49b57c1592 100644
--- a/compiler/src/dmd/frontend.h
+++ b/compiler/src/dmd/frontend.h
@@ -377,6 +377,22 @@ enum class MessageStyle : uint8_t
     sarif = 2u,
 };
 
+struct SourceLoc final
+{
+    _d_dynamicArray< const char > filename;
+    uint32_t line;
+    uint32_t column;
+    uint32_t fileOffset;
+    const char* toChars(bool showColumns = Loc::showColumns, MessageStyle messageStyle = Loc::messageStyle) const;
+    SourceLoc() :
+        filename(),
+        line(),
+        column(),
+        fileOffset()
+    {
+    }
+};
+
 struct Loc final
 {
 private:
@@ -390,7 +406,8 @@ public:
     uint32_t linnum() const;
     const char* filename() const;
     const char* toChars(bool showColumns = Loc::showColumns, MessageStyle messageStyle = Loc::messageStyle) const;
-    bool equals(const Loc& loc) const;
+    SourceLoc toSourceLoc() const;
+    bool equals(Loc loc) const;
     Loc() :
         index(0u)
     {
@@ -4052,8 +4069,6 @@ public:
     bool needsClosure();
     bool hasNestedFrameRefs();
     ParameterList getParameterList();
-    static FuncDeclaration* genCfunc(Array<Parameter* >* fparams, Type* treturn, const char* name, STC stc = (STC)0LLU);
-    static FuncDeclaration* genCfunc(Array<Parameter* >* fparams, Type* treturn, Identifier* id, STC stc = (STC)0LLU);
     virtual FuncDeclaration* toAliasFunc();
     void accept(Visitor* v) override;
 };
@@ -6219,6 +6234,7 @@ enum class CppStdRevision : uint32_t
     cpp14 = 201402u,
     cpp17 = 201703u,
     cpp20 = 202002u,
+    cpp23 = 202302u,
 };
 
 enum class CHECKENABLE : uint8_t
diff --git a/compiler/src/dmd/func.d b/compiler/src/dmd/func.d
index 88e7aeea95..50479f78c8 100644
--- a/compiler/src/dmd/func.d
+++ b/compiler/src/dmd/func.d
@@ -1004,12 +1004,12 @@ extern (C++) class FuncDeclaration : Declaration
     /**********************************
      * Generate a FuncDeclaration for a runtime library function.
      */
-    static FuncDeclaration genCfunc(Parameters* fparams, Type treturn, const(char)* name, STC stc = STC.none)
+    extern(D) static FuncDeclaration genCfunc(Parameters* fparams, Type treturn, const(char)* name, STC stc = STC.none)
     {
         return genCfunc(fparams, treturn, Identifier.idPool(name[0 .. strlen(name)]), stc);
     }
 
-    static FuncDeclaration genCfunc(Parameters* fparams, Type treturn, Identifier id, STC stc = STC.none)
+    extern(D) static FuncDeclaration genCfunc(Parameters* fparams, Type treturn, Identifier id, STC stc = STC.none)
     {
         FuncDeclaration fd;
         TypeFunction tf;
diff --git a/compiler/src/dmd/globals.d b/compiler/src/dmd/globals.d
index 4a637b519c..900c554e5f 100644
--- a/compiler/src/dmd/globals.d
+++ b/compiler/src/dmd/globals.d
@@ -62,6 +62,7 @@ enum CppStdRevision : uint
     cpp14 = 2014_02,
     cpp17 = 2017_03,
     cpp20 = 2020_02,
+    cpp23 = 2023_02,
 }
 
 /// Trivalent boolean to represent the state of a `revert`able change
diff --git a/compiler/src/dmd/globals.h b/compiler/src/dmd/globals.h
index 3e2de5cdf8..69fe709f4b 100644
--- a/compiler/src/dmd/globals.h
+++ b/compiler/src/dmd/globals.h
@@ -73,7 +73,8 @@ enum CppStdRevision
     CppStdRevisionCpp11 = 201103,
     CppStdRevisionCpp14 = 201402,
     CppStdRevisionCpp17 = 201703,
-    CppStdRevisionCpp20 = 202002
+    CppStdRevisionCpp20 = 202002,
+    CppStdRevisionCpp23 = 202302,
 };
 
 /// Trivalent boolean to represent the state of a `revert`able change
@@ -413,6 +414,14 @@ typedef unsigned long long uinteger_t;
 #endif
 
 // file location
+struct SourceLoc
+{
+    DString filename;
+    uint32_t line;
+    uint32_t column;
+    uint32_t fileOffset;
+};
+
 struct Loc
 {
 private:
@@ -438,6 +447,7 @@ public:
     uint32_t charnum() const;
     uint32_t linnum() const;
     const char *filename() const;
+    SourceLoc toSourceLoc() const;
 
     const char *toChars(
         bool showColumns = Loc::showColumns,
diff --git a/compiler/src/dmd/iasmgcc.d b/compiler/src/dmd/iasmgcc.d
index f338ccc8de..f8ebf8fbbb 100644
--- a/compiler/src/dmd/iasmgcc.d
+++ b/compiler/src/dmd/iasmgcc.d
@@ -55,7 +55,8 @@ public Statement gccAsmSemantic(GccAsmStatement s, Scope* sc)
         *ptoklist = null;
     }
     p.token = *toklist;
-    p.scanloc = s.loc;
+    p.baseLoc.startLine = s.loc.linnum;
+    p.linnum = s.loc.linnum;
 
     // Parse the gcc asm statement.
     const errors = global.errors;
diff --git a/compiler/src/dmd/location.d b/compiler/src/dmd/location.d
index a26c0ecc8d..7a579b278f 100644
--- a/compiler/src/dmd/location.d
+++ b/compiler/src/dmd/location.d
@@ -133,6 +133,12 @@ nothrow:
         return this.index - locFileTable[i].startIndex;
     }
 
+    /// Returns: this location as a SourceLoc
+    extern (C++) SourceLoc toSourceLoc() const @nogc @safe
+    {
+        return SourceLoc(this);
+    }
+
     /**
      * Checks for equivalence by comparing the filename contents (not the pointer) and character location.
      *
@@ -140,7 +146,7 @@ nothrow:
      *  - Uses case-insensitive comparison on Windows
      *  - Ignores `charnum` if `Columns` is false.
      */
-    extern (C++) bool equals(ref const(Loc) loc) const
+    extern (C++) bool equals(Loc loc) const
     {
         SourceLoc lhs = SourceLoc(this);
         SourceLoc rhs = SourceLoc(loc);
diff --git a/compiler/src/dmd/mars.d b/compiler/src/dmd/mars.d
index 1b499a47c1..17d6965f53 100644
--- a/compiler/src/dmd/mars.d
+++ b/compiler/src/dmd/mars.d
@@ -1143,6 +1143,9 @@ bool parseCommandLine(const ref Strings arguments, const size_t argc, ref Param
             case "c++20":
                 params.cplusplus = CppStdRevision.cpp20;
                 break;
+            case "c++23":
+                params.cplusplus = CppStdRevision.cpp23;
+                break;
             default:
                 error("switch `%s` is invalid", p);
                 params.help.externStd = true;
diff --git a/compiler/src/dmd/typesem.d b/compiler/src/dmd/typesem.d
index 65bad387ef..c5a3b83379 100644
--- a/compiler/src/dmd/typesem.d
+++ b/compiler/src/dmd/typesem.d
@@ -3444,8 +3444,16 @@ Expression getProperty(Type t, Scope* scope_, Loc loc, Identifier ident, int fla
                 auto s2 = scope_.search_correct(ident);
                 // UFCS
                 if (s2 && s2.isFuncDeclaration)
-                    errorSupplemental(loc, "did you mean %s `%s`?",
-                        s2.kind(), s2.toChars());
+                {
+                    if (s2.ident == ident)
+                    {
+                        errorSupplemental(s2.loc, "cannot call %s `%s` with UFCS because it is not declared at module scope",
+                            s2.kind(), s2.toChars());
+                    }
+                    else
+                        errorSupplemental(s2.loc, "did you mean %s `%s`?",
+                            s2.kind(), s2.toChars());
+                }
                 else if (src.type.ty == Tpointer)
                 {
                     // structPtr.field
@@ -3454,7 +3462,7 @@ Expression getProperty(Type t, Scope* scope_, Loc loc, Identifier ident, int fla
                     {
                         if (auto s3 = as.search_correct(ident))
                         {
-                            errorSupplemental(loc, "did you mean %s `%s`?",
+                            errorSupplemental(s3.loc, "did you mean %s `%s`?",
                                 s3.kind(), s3.toChars());
                         }
                     }
diff --git a/compiler/src/dmd/typinf.h b/compiler/src/dmd/typinf.h
index ea42538573..c34494da2f 100644
--- a/compiler/src/dmd/typinf.h
+++ b/compiler/src/dmd/typinf.h
@@ -14,6 +14,8 @@
 
 class Expression;
 class Type;
+class TypeAArray;
+class TypeInfoDeclaration;
 struct Scope;
 
 namespace dmd
@@ -21,5 +23,7 @@ namespace dmd
     bool genTypeInfo(Expression *e, Loc loc, Type *torig, Scope *sc);
     bool isSpeculativeType(Type *t);
     bool builtinTypeInfo(Type *t);
+    Type *makeNakedAssociativeArray(TypeAArray *t);
+    TypeInfoDeclaration *getTypeInfoAssocArrayDeclaration(TypeAArray *t, Scope *sc);
 }
 Type *getTypeInfoType(Loc loc, Type *t, Scope *sc);
diff --git a/compiler/src/tests/cxxfrontend.cc b/compiler/src/tests/cxxfrontend.cc
index fbe504f4bf..f830236a5e 100644
--- a/compiler/src/tests/cxxfrontend.cc
+++ b/compiler/src/tests/cxxfrontend.cc
@@ -394,6 +394,12 @@ void test_location()
     Loc loc = Loc::singleFilename("app.d");
     assert(strcmp(loc.toChars(true, MessageStyle::digitalmars), "app.d") == 0);
     assert(strcmp(loc.toChars(true, MessageStyle::gnu), "app.d") == 0);
+
+    Loc loc2 = Loc::singleFilename("app2.d");
+    assert(!loc2.equals(loc));
+
+    SourceLoc sloc = loc.toSourceLoc();
+    assert(strcmp(sloc.filename.ptr, loc.filename()) == 0);
 }
 
 /**********************************/
@@ -1730,12 +1736,14 @@ void argtypes_h(Type *t)
     //dmd::isHFVA(t);
 }
 
-void declaration_h(FuncDeclaration *fd, Loc loc, Expressions* args)
+void declaration_h(FuncDeclaration *fd, Loc loc, Expressions* args, Parameters* params)
 {
     dmd::functionSemantic(fd);
     dmd::functionSemantic3(fd);
     ::eval_builtin(loc, fd, args);
     ::isBuiltin(fd);
+    dmd::genCfunc(params, fd->type, "test");
+    dmd::genCfunc(params, fd->type, Identifier::idPool("test"));
 }
 
 void doc_h(Module *m, const char *ptr, d_size_t length, const char *date,
@@ -1868,4 +1876,6 @@ void typinf_h(Expression *e, Loc loc, Type *t, Scope *sc)
     ::getTypeInfoType(loc, t, sc);
     dmd::isSpeculativeType(t);
     dmd::builtinTypeInfo(t);
+    dmd::makeNakedAssociativeArray(t->isTypeAArray());
+    dmd::getTypeInfoAssocArrayDeclaration(t->isTypeAArray(), sc);
 }
diff --git a/compiler/test/fail_compilation/fail347.d b/compiler/test/fail_compilation/fail347.d
index e495ba257e..c56acf5642 100644
--- a/compiler/test/fail_compilation/fail347.d
+++ b/compiler/test/fail_compilation/fail347.d
@@ -5,10 +5,10 @@ TEST_OUTPUT:
 fail_compilation/fail347.d(26): Error: undefined identifier `bbr`, did you mean variable `bar`?
 fail_compilation/fail347.d(27): Error: no property `ofo` for type `S`, did you mean `fail347.S.foo`?
 fail_compilation/fail347.d(29): Error: no property `fool` for `sp` of type `fail347.S*`
-fail_compilation/fail347.d(29):        did you mean variable `foo`?
+fail_compilation/fail347.d(20):        did you mean variable `foo`?
 fail_compilation/fail347.d(30): Error: undefined identifier `strlenx`, did you mean function `strlen`?
 fail_compilation/fail347.d(31): Error: no property `strlenx` for `"hello"` of type `string`
-fail_compilation/fail347.d(31):        did you mean function `strlen`?
+fail_compilation/imports/fail347a.d(3):        did you mean function `strlen`?
 ---
 */
 
diff --git a/compiler/test/fail_compilation/ufcs.d b/compiler/test/fail_compilation/ufcs.d
index 3a92a691e2..87efbcf65c 100644
--- a/compiler/test/fail_compilation/ufcs.d
+++ b/compiler/test/fail_compilation/ufcs.d
@@ -1,23 +1,28 @@
 /*
 TEST_OUTPUT:
 ---
-fail_compilation/ufcs.d(26): Error: no property `regularF` for `s` of type `S`
-fail_compilation/ufcs.d(26):        the following error occured while looking for a UFCS match
-fail_compilation/ufcs.d(26): Error: function `regularF` is not callable using argument types `(S)`
-fail_compilation/ufcs.d(26):        expected 0 argument(s), not 1
-fail_compilation/ufcs.d(31):        `ufcs.regularF()` declared here
-fail_compilation/ufcs.d(27): Error: no property `templateF` for `s` of type `S`
-fail_compilation/ufcs.d(27):        the following error occured while looking for a UFCS match
-fail_compilation/ufcs.d(27): Error: template `templateF` is not callable using argument types `!()(S)`
-fail_compilation/ufcs.d(32):        Candidate is: `templateF()()`
-fail_compilation/ufcs.d(28): Error: no property `templateO` for `s` of type `S`
-fail_compilation/ufcs.d(28):        the following error occured while looking for a UFCS match
-fail_compilation/ufcs.d(28): Error: none of the overloads of template `ufcs.templateO` are callable using argument types `!()(S)`
-fail_compilation/ufcs.d(34):        Candidates are: `templateO()(int x)`
-fail_compilation/ufcs.d(35):                        `templateO()(float y)`
+fail_compilation/ufcs.d(31): Error: no property `regularF` for `s` of type `S`
+fail_compilation/ufcs.d(31):        the following error occured while looking for a UFCS match
+fail_compilation/ufcs.d(31): Error: function `regularF` is not callable using argument types `(S)`
+fail_compilation/ufcs.d(31):        expected 0 argument(s), not 1
+fail_compilation/ufcs.d(39):        `ufcs.regularF()` declared here
+fail_compilation/ufcs.d(32): Error: no property `templateF` for `s` of type `S`
+fail_compilation/ufcs.d(32):        the following error occured while looking for a UFCS match
+fail_compilation/ufcs.d(32): Error: template `templateF` is not callable using argument types `!()(S)`
+fail_compilation/ufcs.d(40):        Candidate is: `templateF()()`
+fail_compilation/ufcs.d(33): Error: no property `templateO` for `s` of type `S`
+fail_compilation/ufcs.d(33):        the following error occured while looking for a UFCS match
+fail_compilation/ufcs.d(33): Error: none of the overloads of template `ufcs.templateO` are callable using argument types `!()(S)`
+fail_compilation/ufcs.d(42):        Candidates are: `templateO()(int x)`
+fail_compilation/ufcs.d(43):                        `templateO()(float y)`
+fail_compilation/ufcs.d(36): Error: no property `local` for `s` of type `ufcs.S`
+fail_compilation/ufcs.d(35):        cannot call function `local` with UFCS because it is not declared at module scope
+fail_compilation/ufcs.d(26):        struct `S` defined here
 ---
 */
 
+
+
 struct S { }
 
 void f()
@@ -26,6 +31,9 @@ void f()
     s.regularF();
     s.templateF();
     s.templateO();
+
+    void local(S) {}
+    s.local();
 }
 
 void regularF();
diff --git a/compiler/test/runnable/test21020.d b/compiler/test/runnable/test21020.d
new file mode 100644
index 0000000000..484db30a56
--- /dev/null
+++ b/compiler/test/runnable/test21020.d
@@ -0,0 +1,11 @@
+// https://github.com/dlang/dmd/issues/21020
+
+shared struct Queue {
+    int[int] map;
+}
+
+void main() {
+    auto queue = Queue();
+    (cast(int[int]) queue.map)[1] = 2;
+    assert(queue.map[1] == 2);
+}
diff --git a/druntime/Makefile b/druntime/Makefile
index 2efde5c940..2c022c6997 100644
--- a/druntime/Makefile
+++ b/druntime/Makefile
@@ -479,7 +479,7 @@ TESTS_EXTRACTOR=$(ROOT)/tests_extractor$(DOTEXE)
 BETTERCTESTS_DIR=$(ROOT)/betterctests
 
 # macro that returns the module name given the src path
-moduleName=$(subst rt.invariant,invariant,$(subst object_,object,$(subst /,.,$(1))))
+moduleName=$(subst /,.,$(1))
 
 $(ROOT)/unittest/% : $(ROOT)/unittest/test_runner$(DOTEXE)
 	@mkdir -p $(dir $@)
diff --git a/druntime/mak/DOCS b/druntime/mak/DOCS
index 0fb4a37362..574a18b19c 100644
--- a/druntime/mak/DOCS
+++ b/druntime/mak/DOCS
@@ -548,7 +548,7 @@ DOCS=\
 	$(DOCDIR)\rt_deh_win32.html \
 	$(DOCDIR)\rt_deh_win64_posix.html \
 	$(DOCDIR)\rt_ehalloc.html \
-	$(DOCDIR)\rt_invariant.html \
+	$(DOCDIR)\rt_invariant_.html \
 	$(DOCDIR)\rt_llmath.html \
 	$(DOCDIR)\rt_memory.html \
 	$(DOCDIR)\rt_memset.html \
diff --git a/druntime/mak/SRCS b/druntime/mak/SRCS
index 172dadcc24..9e7c438d77 100644
--- a/druntime/mak/SRCS
+++ b/druntime/mak/SRCS
@@ -573,7 +573,7 @@ SRCS=\
 	src\rt\dmain2.d \
 	src\rt\dwarfeh.d \
 	src\rt\ehalloc.d \
-	src\rt\invariant.d \
+	src\rt\invariant_.d \
 	src\rt\lifetime.d \
 	src\rt\llmath.d \
 	src\rt\memory.d \
diff --git a/druntime/src/core/stdcpp/xutility.d b/druntime/src/core/stdcpp/xutility.d
index 5e2e711ba6..f93df68deb 100644
--- a/druntime/src/core/stdcpp/xutility.d
+++ b/druntime/src/core/stdcpp/xutility.d
@@ -35,6 +35,7 @@ enum CppStdRevision : uint
     cpp14 = 201402,
     cpp17 = 201703,
     cpp20 = 202002,
+    cpp23 = 202302,
 }
 
 /**
diff --git a/druntime/src/etc/linux/memoryerror.d b/druntime/src/etc/linux/memoryerror.d
index 31e1d83796..b44a7f6d68 100644
--- a/druntime/src/etc/linux/memoryerror.d
+++ b/druntime/src/etc/linux/memoryerror.d
@@ -40,7 +40,7 @@ version (linux)
 
 version (MemoryErrorSupported)
     version = AnySupported;
-else version (MemoryErrorSupported)
+else version (MemoryAssertSupported)
     version = AnySupported;
 
 version (AnySupported):
diff --git a/druntime/src/rt/cover.d b/druntime/src/rt/cover.d
index 7bc5ffbf11..0b1902104c 100644
--- a/druntime/src/rt/cover.d
+++ b/druntime/src/rt/cover.d
@@ -27,7 +27,7 @@ else version (Posix)
 {
     import core.stdc.stdio : fopen;
     import core.sys.posix.fcntl : O_CREAT, O_RDWR, open, S_IRGRP, S_IROTH, S_IRUSR, S_IWGRP, S_IWOTH, S_IWUSR;
-    import core.sys.posix.unistd : F_LOCK, ftruncate, lockf;
+    import core.sys.posix.unistd : ftruncate;
 }
 else
     static assert(0, "Unsupported platform");
@@ -487,7 +487,10 @@ void lockFile(int fd)
         flock(fd, LOCK_EX); // exclusive lock
     }
     else version (Posix)
+    {
+        import core.sys.posix.unistd : F_LOCK, lockf;
         lockf(fd, F_LOCK, 0); // exclusive lock
+    }
     else version (Windows)
     {
         OVERLAPPED off;
diff --git a/druntime/src/rt/invariant.d b/druntime/src/rt/invariant_.d
similarity index 70%
rename from druntime/src/rt/invariant.d
rename to druntime/src/rt/invariant_.d
index e536196e8c..2a64dc89da 100644
--- a/druntime/src/rt/invariant.d
+++ b/druntime/src/rt/invariant_.d
@@ -4,15 +4,10 @@
  * Copyright: Copyright Digital Mars 2007 - 2010.
  * License:   $(HTTP www.boost.org/LICENSE_1_0.txt, Boost License 1.0).
  * Authors:   Walter Bright
- * Source: $(DRUNTIMESRC rt/_invariant.d)
- */
-
-/*          Copyright Digital Mars 2007 - 2010.
- * Distributed under the Boost Software License, Version 1.0.
- *    (See accompanying file LICENSE or copy at
- *          http://www.boost.org/LICENSE_1_0.txt)
+ * Source: $(DRUNTIMESRC rt/_invariant_.d)
  */
 
+module rt.invariant_;
 
 /**
  *