diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index b3fcb82b07..69d289f317 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -58,8 +58,9 @@ jobs:
           #   os: macos-13
           #   host_dmd: dmd
           #   coverage: true
-          - job_name: macOS 12 x64, DMD (bootstrap)
-            os: macos-12
+          - job_name: macOS 13 x64, DMD (bootstrap)
+            os: macos-13
+            xcode: '14.3.1' # work around 'ld: multiple errors: symbol count from symbol table and dynamic symbol table differ' with old bootstrap compiler
             # de-facto bootstrap version on OSX
             # See: https://github.com/dlang/dmd/pull/13890
             host_dmd: dmd-2.099.1
@@ -100,12 +101,9 @@ jobs:
         if: runner.os != 'Windows'
         run: ${{ runner.os == 'macOS' && 'ci/cirrusci.sh' || 'sudo -E ci/cirrusci.sh' }}
 
-      # NOTE: Linker ICEs with Xcode 15.0.1 (default version on macos-13)
-      # * https://issues.dlang.org/show_bug.cgi?id=24407
-      # Remove this step if the default gets changed to 15.1 in actions/runner-images.
-      - name: 'macOS 13: Switch to Xcode v15.1'
-        if: matrix.os == 'macos-13'
-        run: sudo xcode-select -switch /Applications/Xcode_15.1.app
+      - name: 'macOS: Switch Xcode version if required'
+        if: runner.os == 'macOS' && matrix.xcode
+        run: sudo xcode-select -switch /Applications/Xcode_${{ matrix.xcode }}.app
 
       - name: 'Posix: Install host compiler'
         if: runner.os != 'Windows'
diff --git a/.github/workflows/runnable_cxx.yml b/.github/workflows/runnable_cxx.yml
index dc701907cd..224ae6fd85 100644
--- a/.github/workflows/runnable_cxx.yml
+++ b/.github/workflows/runnable_cxx.yml
@@ -57,10 +57,10 @@ jobs:
       # very few PRs actually benefit from this.
       fail-fast: false
       matrix:
-        os: [ macOS-12, ubuntu-20.04, windows-2019 ]
+        os: [ macos-13, ubuntu-20.04, windows-2019 ]
 
         target: [
-          # Versions of clang earlier than 11 are not available on 20.04, but are on macOS-12
+          # Versions of clang earlier than 11 are not available on 20.04, but are on macOS 13
           clang-13.0.0, clang-12.0.0, clang-11.0.0, clang-10.0.0, clang-9.0.0, clang-8.0.0,
         # For g++, we test the oldest compiler on Ubuntu 20.04, which is GCC-9
           g++-11, g++-10, g++-9,
@@ -81,13 +81,13 @@ jobs:
           - { os: ubuntu-20.04, target: msvc-2015 }
           - { os: ubuntu-20.04, target: msvc-2013 }
           # OSX only supports clang
-          - { os: macOS-12, target: g++-11 }
-          - { os: macOS-12, target: g++-10 }
-          - { os: macOS-12, target: g++-9 }
-          - { os: macOS-12, target: msvc-2019 }
-          - { os: macOS-12, target: msvc-2017 }
-          - { os: macOS-12, target: msvc-2015 }
-          - { os: macOS-12, target: msvc-2013 }
+          - { os: macos-13, target: g++-11 }
+          - { os: macos-13, target: g++-10 }
+          - { os: macos-13, target: g++-9 }
+          - { os: macos-13, target: msvc-2019 }
+          - { os: macos-13, target: msvc-2017 }
+          - { os: macos-13, target: msvc-2015 }
+          - { os: macos-13, target: msvc-2013 }
           # We don't test g++ on Windows as DMD only mangles for MSVC
           - { os: windows-2019, target: g++-11 }
           - { os: windows-2019, target: g++-10 }
@@ -126,13 +126,13 @@ jobs:
           - { target: g++-9, compiler: g++, cxx-version: 9.4.0, major: 9 }
           # Platform boilerplate
           - { os: ubuntu-20.04, arch: x86_64-linux-gnu-ubuntu-20.04 }
-          - { os: macOS-12,  arch: x86_64-apple-darwin }
+          - { os: macos-13,  arch: x86_64-apple-darwin }
           # Clang 9.0.0 have a different arch for OSX
-          - { os: macOS-12, target: clang-9.0.0, arch: x86_64-darwin-apple }
+          - { os: macos-13, target: clang-9.0.0, arch: x86_64-darwin-apple }
           # Those targets will generate artifacts that can be used by other testers
           - { storeArtifacts: false }
           - { os: ubuntu-20.04, target: g++-9,    storeArtifacts: true }
-          - { os: macOS-12,  target: clang-9.0.0, storeArtifacts: true }
+          - { os: macos-13,  target: clang-9.0.0, storeArtifacts: true }
           #- { os: windows-2019, target: msvc-2019,   storeArtifacts: true }
 
     # We're using the latest available images at the time of this commit.
@@ -209,7 +209,7 @@ jobs:
         # On OSX, the system header are installed via `xcode-select` and not distributed with clang
         # Since some part of the testsuite rely on CC and CXX being only a binary (not a command),
         # and config files where only introduced from 6.0.0, use a wrapper script.
-        if [ "${{ matrix.os }}" == "macOS-12" ]; then
+        if [ "${{ matrix.os }}" == "macos-13" ]; then
           # Note: heredoc shouldn't be indented
           cat << 'EOF' > ${TMP_CC}-wrapper
         #!/bin/bash
@@ -227,11 +227,15 @@ jobs:
           chmod +x ${TMP_CC}-wrapper ${TMP_CC}++-wrapper
         fi
 
+    - name: 'macOS 13: Switch to Xcode v14.3.1' # to work around '-macosx_version_min has been renamed to -macos_version_min' with some clang versions
+      if: matrix.os == 'macos-13'
+      run: sudo xcode-select -switch /Applications/Xcode_14.3.1.app
+
     - name: '[Posix] Setup environment variables'
       if: matrix.compiler == 'clang' && runner.os != 'Windows'
       run: |
         TMP_CC='${{ github.workspace }}/clang+llvm-${{ matrix.cxx-version }}-${{ matrix.arch }}/bin/clang'
-        if [ "${{ matrix.os }}" == "macOS-12" ]; then
+        if [ "${{ matrix.os }}" == "macos-13" ]; then
           echo "CC=${TMP_CC}-wrapper" >> $GITHUB_ENV
           echo "CXX=${TMP_CC}++-wrapper" >> $GITHUB_ENV
           echo "SDKROOT=$(xcrun --show-sdk-path)" >> $GITHUB_ENV
diff --git a/ci/README.md b/ci/README.md
index ec1c6bf5ba..d9f989dc11 100644
--- a/ci/README.md
+++ b/ci/README.md
@@ -112,12 +112,12 @@ The auto tester tests DMD on various Posix platforms.
 **Config**: [azure-pipelines.yml](https://github.com/dlang/dmd/blob/master/.github/workflows/runnable_cxx.yml)
 
 **Checks**:
-- C++ interop tests / Run (macOS-12, clang-13.0.0)
-- C++ interop tests / Run (macOS-12, clang-12.0.0)
-- C++ interop tests / Run (macOS-12, clang-11.0.0)
-- C++ interop tests / Run (macOS-12, clang-10.0.0)
-- C++ interop tests / Run (macOS-12, clang-9.0.0)
-- C++ interop tests / Run (macOS-12, clang-8.0.0)
+- C++ interop tests / Run (macos-13, clang-13.0.0)
+- C++ interop tests / Run (macos-13, clang-12.0.0)
+- C++ interop tests / Run (macos-13, clang-11.0.0)
+- C++ interop tests / Run (macos-13, clang-10.0.0)
+- C++ interop tests / Run (macos-13, clang-9.0.0)
+- C++ interop tests / Run (macos-13, clang-8.0.0)
 - C++ interop tests / Run (ubuntu-20.04, clang-13.0.0)
 - C++ interop tests / Run (ubuntu-20.04, clang-12.0.0)
 - C++ interop tests / Run (ubuntu-20.04, clang-11.0.0)
diff --git a/compiler/src/dmd/dcast.d b/compiler/src/dmd/dcast.d
index 34b120b341..b08e2bed2d 100644
--- a/compiler/src/dmd/dcast.d
+++ b/compiler/src/dmd/dcast.d
@@ -2335,7 +2335,7 @@ Expression castTo(Expression e, Scope* sc, Type t, Type att = null)
         Type tb = t.toBasetype();
         Type typeb = e.type.toBasetype();
 
-        if (e.hexString && !e.committed)
+        if (e.hexString && !e.committed && tb.nextOf().isintegral)
         {
             const szx = cast(ubyte) tb.nextOf().size();
             if (szx != se.sz && (e.len % szx) == 0)
diff --git a/compiler/src/dmd/dinterpret.d b/compiler/src/dmd/dinterpret.d
index 4e04a27214..1184fb9516 100644
--- a/compiler/src/dmd/dinterpret.d
+++ b/compiler/src/dmd/dinterpret.d
@@ -6132,7 +6132,7 @@ public:
         {
             auto se = e1.isStringExp();
             // Allow casting a hex string literal to short[], int[] or long[]
-            if (se && se.hexString && se.postfix == StringExp.NoPostfix)
+            if (se && se.hexString && se.postfix == StringExp.NoPostfix && e.to.nextOf().isintegral)
             {
                 const sz = cast(size_t) e.to.nextOf().size;
                 if ((se.len % sz) != 0)
diff --git a/compiler/src/dmd/enumsem.d b/compiler/src/dmd/enumsem.d
index 99211e4985..e22bdba349 100644
--- a/compiler/src/dmd/enumsem.d
+++ b/compiler/src/dmd/enumsem.d
@@ -185,7 +185,7 @@ void enumSemantic(Scope* sc, EnumDeclaration ed)
 
     if (ed.members.length == 0)
     {
-        .error(ed.loc, "%s `%s enum `%s` must have at least one member", ed.kind, ed.toPrettyChars, ed.toChars());
+        .error(ed.loc, "%s `%s` enum `%s` must have at least one member", ed.kind, ed.toPrettyChars, ed.toChars());
         ed.errors = true;
         ed.semanticRun = PASS.semanticdone;
         return;
diff --git a/compiler/src/dmd/expressionsem.d b/compiler/src/dmd/expressionsem.d
index 6e2aeb46ed..86a35cf05b 100644
--- a/compiler/src/dmd/expressionsem.d
+++ b/compiler/src/dmd/expressionsem.d
@@ -15067,6 +15067,27 @@ bool checkSharedAccess(Expression e, Scope* sc, bool returnRef = false)
     {
         return false;
     }
+    else if (sc._module.ident == Id.atomic && sc._module.parent !is null)
+    {
+        // Allow core.internal.atomic, it is an compiler implementation for a given platform module.
+        // It is then exposed by other modules such as core.atomic and core.stdc.atomic.
+        // This is available as long as druntime is on the import path and the platform supports that operation.
+
+        // https://issues.dlang.org/show_bug.cgi?id=24846
+
+        Package parent = sc._module.parent.isPackage();
+        if (parent !is null)
+        {
+            // This can be easily converted over to apply to core.atomic and core.internal.atomic
+            if (parent.ident == Id.internal)
+            {
+                parent = parent.parent.isPackage();
+
+                if (parent !is null && parent.ident == Id.core && parent.parent is null)
+                   return false;
+            }
+        }
+    }
 
     //printf("checkSharedAccess() `%s` returnRef: %d\n", e.toChars(), returnRef);
 
diff --git a/compiler/src/dmd/frontend.h b/compiler/src/dmd/frontend.h
index 364dcb3fac..44f65921ea 100644
--- a/compiler/src/dmd/frontend.h
+++ b/compiler/src/dmd/frontend.h
@@ -8836,6 +8836,7 @@ struct Id final
     static Identifier* va_start;
     static Identifier* std;
     static Identifier* core;
+    static Identifier* internal;
     static Identifier* config;
     static Identifier* c_complex_float;
     static Identifier* c_complex_double;
diff --git a/compiler/src/dmd/id.d b/compiler/src/dmd/id.d
index b60172d051..3aacc9cc98 100644
--- a/compiler/src/dmd/id.d
+++ b/compiler/src/dmd/id.d
@@ -389,6 +389,7 @@ immutable Msgtable[] msgtable =
     // Builtin functions
     { "std" },
     { "core" },
+    { "internal" },
     { "config" },
     { "c_complex_float" },
     { "c_complex_double" },
diff --git a/compiler/src/dmd/lexer.d b/compiler/src/dmd/lexer.d
index 476a700bde..95eef80cd0 100644
--- a/compiler/src/dmd/lexer.d
+++ b/compiler/src/dmd/lexer.d
@@ -1555,6 +1555,8 @@ class Lexer
                     if (ndigits != 2 && !utf_isValidDchar(v))
                     {
                         error(loc, "invalid UTF character \\U%08x", v);
+                        if (v >= 0xD800 && v <= 0xDFFF)
+                            errorSupplemental("The code unit is a UTF-16 surrogate, is the escape UTF-16 not a Unicode code point?");
                         v = '?'; // recover with valid UTF character
                     }
                 }
@@ -3168,6 +3170,11 @@ class Lexer
         eSink.error(loc, format, args);
     }
 
+    void errorSupplemental(T...)(const(char)* format, T args)
+    {
+        eSink.errorSupplemental(token.loc, format, args);
+    }
+
     void deprecation(T...)(const ref Loc loc, const(char)* format, T args)
     {
         eSink.deprecation(loc, format, args);
@@ -3671,6 +3678,7 @@ unittest
         import core.stdc.stdarg;
 
         string expected;
+        string expectedSupplemental;
         bool gotError;
 
         void error(const ref Loc loc, const(char)* format, ...)
@@ -3683,13 +3691,25 @@ unittest
             va_end(ap);
             assert(expected == actual);
         }
+
+        void errorSupplemental(const ref Loc loc, const(char)* format, ...)
+        {
+            gotError = true;
+            char[128] buffer = void;
+            va_list ap;
+            va_start(ap, format);
+            auto actual = buffer[0 .. vsnprintf(buffer.ptr, buffer.length, format, ap)];
+            va_end(ap);
+            assert(expectedSupplemental == actual);
+        }
     }
 
     ErrorSinkTest errorSink = new ErrorSinkTest;
 
-    void test(string sequence, string expectedError, dchar expectedReturnValue, uint expectedScanLength, bool Ccompile = false)
+    void test2(string sequence, string[2] expectedError, dchar expectedReturnValue, uint expectedScanLength, bool Ccompile = false)
     {
-        errorSink.expected = expectedError;
+        errorSink.expected = expectedError[0];
+        errorSink.expectedSupplemental = expectedError[1];
         errorSink.gotError = false;
         auto p = cast(const(char)*)sequence.ptr;
         Lexer lexer = new Lexer(errorSink);
@@ -3702,6 +3722,11 @@ unittest
         assert(expectedScanLength == actualScanLength);
     }
 
+    void test(string sequence, string expectedError, dchar expectedReturnValue, uint expectedScanLength, bool Ccompile = false)
+    {
+        test2(sequence, [expectedError, null], expectedReturnValue, expectedScanLength, Ccompile);
+    }
+
     test("c", `undefined escape sequence \c`, 'c', 1);
     test("!", `undefined escape sequence \!`, '!', 1);
     test("&quot;", `undefined escape sequence \&`, '&', 1, true);
@@ -3720,8 +3745,6 @@ unittest
     test("U0001f6" , `escape hex sequence has 6 hex digits instead of 8`,  0x0001f6, 7);
     test("U0001f60", `escape hex sequence has 7 hex digits instead of 8`, 0x0001f60, 8);
 
-    test("ud800"    , `invalid UTF character \U0000d800`, '?', 5);
-    test("udfff"    , `invalid UTF character \U0000dfff`, '?', 5);
     test("U00110000", `invalid UTF character \U00110000`, '?', 9);
 
     test("xg0"      , `undefined escape hex sequence \xg`, 'g', 2);
@@ -3733,6 +3756,9 @@ unittest
     test("&quot", `unterminated named entity &quot;`, '?', 5);
 
     test("400", `escape octal sequence \400 is larger than \377`, 0x100, 3);
+
+    test2("uD800", [`invalid UTF character \U0000d800`, `The code unit is a UTF-16 surrogate, is the escape UTF-16 not a Unicode code point?`], '?', 5);
+    test2("uDFFF", [`invalid UTF character \U0000dfff`, `The code unit is a UTF-16 surrogate, is the escape UTF-16 not a Unicode code point?`], '?', 5);
 }
 
 unittest
diff --git a/compiler/test/compilable/atomic_store_2_shared_classes.d b/compiler/test/compilable/atomic_loadstore_shared_classes.d
similarity index 60%
rename from compiler/test/compilable/atomic_store_2_shared_classes.d
rename to compiler/test/compilable/atomic_loadstore_shared_classes.d
index 0d8cd74893..f719aa829f 100644
--- a/compiler/test/compilable/atomic_store_2_shared_classes.d
+++ b/compiler/test/compilable/atomic_loadstore_shared_classes.d
@@ -5,9 +5,14 @@ class Foo
 {
 }
 
+shared Foo toLoad;
+
 void oops()
 {
     auto f0 = new shared Foo;
     auto f1 = new shared Foo;
     atomicStore(f0, f1);
+
+    // https://issues.dlang.org/show_bug.cgi?id=24846
+    shared(Foo) f2 = atomicLoad(toLoad);
 }
diff --git a/compiler/test/fail_compilation/diag24812.d b/compiler/test/fail_compilation/diag24812.d
new file mode 100644
index 0000000000..626f47ebf0
--- /dev/null
+++ b/compiler/test/fail_compilation/diag24812.d
@@ -0,0 +1,7 @@
+/*
+TEST_OUTPUT:
+---
+fail_compilation/diag24812.d(7): Error: enum `diag24812.Foo` enum `Foo` must have at least one member
+---
+*/
+enum Foo {}
diff --git a/compiler/test/fail_compilation/hexstring.d b/compiler/test/fail_compilation/hexstring.d
index 0f23f44438..edbb4e67bc 100644
--- a/compiler/test/fail_compilation/hexstring.d
+++ b/compiler/test/fail_compilation/hexstring.d
@@ -14,6 +14,7 @@ fail_compilation/hexstring.d(39):        perhaps remove postfix `c` from hex str
 fail_compilation/hexstring.d(40): Error: hex string with `dstring` type needs to be multiple of 4 bytes, not 5
 fail_compilation/hexstring.d(41): Error: cannot implicitly convert expression `x"11223344"d` of type `dstring` to `immutable(float[])`
 fail_compilation/hexstring.d(42): Error: cannot implicitly convert expression `x"1122"w` of type `wstring` to `immutable(ubyte[])`
+fail_compilation/hexstring.d(50): Error: array cast from `string` to `S[]` is not supported at compile time
 fail_compilation/hexstring.d(28): Error: cannot implicitly convert expression `x"123F"` of type `string` to `ubyte[]`
 ---
 */
@@ -21,7 +22,6 @@ immutable ubyte[] s0 = x"123F";
 static assert(s0[0] == 0x12);
 static assert(s0[1] == 0x3F);
 immutable byte[] s1 = x"123F";
-
 enum E(X) = cast(X[]) x"AABBCCDD";
 static assert(E!int[0] == 0xAABBCCDD);
 
@@ -40,3 +40,11 @@ immutable uint[] f11 = cast(immutable uint[]) x"AABBCCDD"c;
 immutable uint[] f12 = x"1122334455"d;
 immutable float[] f13 = x"11223344"d;
 immutable ubyte[] f14 = x"1122"w;
+
+// https://issues.dlang.org/show_bug.cgi?id=24832
+struct S
+{
+    ushort l0, l1, l2, l3, l4, l5;
+}
+
+immutable S[] returnValues = cast(S[]) x"FFFFFFFFFFFFFFFFFFFFFFFF";
diff --git a/druntime/src/importc.h b/druntime/src/importc.h
index 858e502b99..b7b82dbe6b 100644
--- a/druntime/src/importc.h
+++ b/druntime/src/importc.h
@@ -41,6 +41,7 @@
 #define __alignof _Alignof
 #define __vector_size__ vector_size
 #define __typeof typeof
+#define __typeof__ typeof
 
 /********************
  * Clang nullability extension used by macOS headers.