DavidCozens · DavidCozens · May 4, 2026 · May 4, 2026 · May 4, 2026 · May 4, 2026
diff --git a/.clang-tidy b/.clang-tidy
@@ -21,7 +21,8 @@ Checks: >
   -performance-enum-size,
   -cppcoreguidelines-pro-bounds-pointer-arithmetic,
   -cppcoreguidelines-avoid-c-arrays,
-  -modernize-avoid-c-arrays
+  -modernize-avoid-c-arrays,
+  -modernize-deprecated-headers
 
 # Treat all clang-tidy warnings as errors.
 WarningsAsErrors: '*'

diff --git a/CMakeLists.txt b/CMakeLists.txt
@@ -4,6 +4,7 @@ project(SolidSyslog C CXX)
 list(APPEND CMAKE_MODULE_PATH "${CMAKE_SOURCE_DIR}/cmake")
 include(LayerGuard)
 solidsyslog_enforce_layering()
+include(Iwyu)
 
 set(CMAKE_C_STANDARD 11)
 set(CMAKE_C_STANDARD_REQUIRED ON)

diff --git a/CMakePresets.json b/CMakePresets.json
@@ -71,6 +71,14 @@
                 "CMAKE_EXE_LINKER_FLAGS": "-no-pie"
             }
         },
+        {
+            "name": "iwyu",
+            "displayName": "Include-What-You-Use",
+            "inherits": "clang-debug",
+            "cacheVariables": {
+                "ENABLE_IWYU": "ON"
+            }
+        },
         {
             "name": "msvc-base",
             "hidden": true,
@@ -98,6 +106,7 @@
         { "name": "tidy",        "configurePreset": "tidy" },
         { "name": "cppcheck",    "configurePreset": "cppcheck" },
         { "name": "clang-debug", "configurePreset": "clang-debug" },
+        { "name": "iwyu",        "configurePreset": "iwyu" },
         { "name": "msvc-debug",  "configurePreset": "msvc-debug", "configuration": "Debug" }
     ],
     "testPresets": [

diff --git a/Core/Interface/SolidSyslogBlockDeviceDefinition.h b/Core/Interface/SolidSyslogBlockDeviceDefinition.h
@@ -1,7 +1,10 @@
 #ifndef SOLIDSYSLOGBLOCKDEVICEDEFINITION_H
 #define SOLIDSYSLOGBLOCKDEVICEDEFINITION_H
 
-#include "SolidSyslogBlockDevice.h"
+#include <stdbool.h>
+#include <stddef.h>
+
+#include "ExternC.h"
 
 EXTERN_C_BEGIN
 

diff --git a/Core/Interface/SolidSyslogBlockStore.h b/Core/Interface/SolidSyslogBlockStore.h
@@ -1,12 +1,14 @@
 #ifndef SOLIDSYSLOGBLOCKSTORE_H
 #define SOLIDSYSLOGBLOCKSTORE_H
 
+#include <stddef.h>
+#include <stdint.h>
+
 #include "SolidSyslog.h"
 #include "SolidSyslogSecurityPolicyDefinition.h"
-#include "SolidSyslogStore.h"
+#include "ExternC.h"
 
-#include <stddef.h>
-#include <stdint.h>
+struct SolidSyslogStore;
 
 EXTERN_C_BEGIN
 

diff --git a/Core/Interface/SolidSyslogBufferDefinition.h b/Core/Interface/SolidSyslogBufferDefinition.h
@@ -1,7 +1,10 @@
 #ifndef SOLIDSYSLOGBUFFERDEFINITION_H
 #define SOLIDSYSLOGBUFFERDEFINITION_H
 
-#include "SolidSyslogBuffer.h"
+#include <stdbool.h>
+#include <stddef.h>
+
+#include "ExternC.h"
 
 EXTERN_C_BEGIN
 

diff --git a/Core/Interface/SolidSyslogConfig.h b/Core/Interface/SolidSyslogConfig.h
@@ -1,11 +1,11 @@
 #ifndef SOLIDSYSLOGCONFIG_H
 #define SOLIDSYSLOGCONFIG_H
 
-#include "SolidSyslog.h"
+#include <stddef.h>
+
 #include "SolidSyslogStringFunction.h"
 #include "SolidSyslogTimestamp.h"
-
-#include <stddef.h>
+#include "ExternC.h"
 
 EXTERN_C_BEGIN
 

diff --git a/Core/Interface/SolidSyslogCrc16Policy.h b/Core/Interface/SolidSyslogCrc16Policy.h
@@ -1,7 +1,7 @@
 #ifndef SOLIDSYSLOGCRC16POLICY_H
 #define SOLIDSYSLOGCRC16POLICY_H
 
-#include "SolidSyslogSecurityPolicyDefinition.h"
+#include "ExternC.h"
 
 EXTERN_C_BEGIN
 

diff --git a/Core/Interface/SolidSyslogDatagram.h b/Core/Interface/SolidSyslogDatagram.h
@@ -1,11 +1,13 @@
 #ifndef SOLIDSYSLOGDATAGRAM_H
 #define SOLIDSYSLOGDATAGRAM_H
 
-#include "ExternC.h"
-#include "SolidSyslogAddress.h"
 #include <stdbool.h>
 #include <stddef.h>
 
+#include "ExternC.h"
+
+struct SolidSyslogAddress;
+
 EXTERN_C_BEGIN
 
     struct SolidSyslogDatagram;

diff --git a/Core/Interface/SolidSyslogDatagramDefinition.h b/Core/Interface/SolidSyslogDatagramDefinition.h
@@ -1,7 +1,13 @@
 #ifndef SOLIDSYSLOGDATAGRAMDEFINITION_H
 #define SOLIDSYSLOGDATAGRAMDEFINITION_H
 
+#include <stdbool.h>
+#include <stddef.h>
+
 #include "SolidSyslogDatagram.h"
+#include "ExternC.h"
+
+struct SolidSyslogAddress;
 
 EXTERN_C_BEGIN
 

diff --git a/Core/Interface/SolidSyslogEndpoint.h b/Core/Interface/SolidSyslogEndpoint.h
@@ -1,11 +1,10 @@
 #ifndef SOLIDSYSLOGENDPOINT_H
 #define SOLIDSYSLOGENDPOINT_H
 
-#include "ExternC.h"
-#include "SolidSyslogFormatter.h"
-
 #include <stdint.h>
 
+#include "ExternC.h"
+
 EXTERN_C_BEGIN
 
     enum

diff --git a/Core/Interface/SolidSyslogFileBlockDevice.h b/Core/Interface/SolidSyslogFileBlockDevice.h
@@ -1,11 +1,13 @@
 #ifndef SOLIDSYSLOGFILEBLOCKDEVICE_H
 #define SOLIDSYSLOGFILEBLOCKDEVICE_H
 
-#include "SolidSyslogBlockDevice.h"
-#include "SolidSyslogFile.h"
-
 #include <stdint.h>
 
+#include "ExternC.h"
+
+struct SolidSyslogBlockDevice;
+struct SolidSyslogFile;
+
 EXTERN_C_BEGIN
 
     enum

diff --git a/Core/Interface/SolidSyslogFileDefinition.h b/Core/Interface/SolidSyslogFileDefinition.h
@@ -1,7 +1,10 @@
 #ifndef SOLIDSYSLOGFILEDEFINITION_H
 #define SOLIDSYSLOGFILEDEFINITION_H
 
-#include "SolidSyslogFile.h"
+#include <stdbool.h>
+#include <stddef.h>
+
+#include "ExternC.h"
 
 EXTERN_C_BEGIN
 

diff --git a/Core/Interface/SolidSyslogNullBuffer.h b/Core/Interface/SolidSyslogNullBuffer.h
@@ -1,7 +1,7 @@
 #ifndef SOLIDSYSLOGNULLBUFFER_H
 #define SOLIDSYSLOGNULLBUFFER_H
 
-#include "SolidSyslogBuffer.h"
+#include "ExternC.h"
 
 EXTERN_C_BEGIN
 

diff --git a/Core/Interface/SolidSyslogNullSecurityPolicy.h b/Core/Interface/SolidSyslogNullSecurityPolicy.h
@@ -1,7 +1,7 @@
 #ifndef SOLIDSYSLOGNULLSECURITYPOLICY_H
 #define SOLIDSYSLOGNULLSECURITYPOLICY_H
 
-#include "SolidSyslogSecurityPolicyDefinition.h"
+#include "ExternC.h"
 
 EXTERN_C_BEGIN
 

diff --git a/Core/Interface/SolidSyslogNullStore.h b/Core/Interface/SolidSyslogNullStore.h
@@ -1,7 +1,7 @@
 #ifndef SOLIDSYSLOGNULLSTORE_H
 #define SOLIDSYSLOGNULLSTORE_H
 
-#include "SolidSyslogStore.h"
+#include "ExternC.h"
 
 EXTERN_C_BEGIN
 

diff --git a/Core/Interface/SolidSyslogResolver.h b/Core/Interface/SolidSyslogResolver.h
@@ -1,12 +1,14 @@
 #ifndef SOLIDSYSLOGRESOLVER_H
 #define SOLIDSYSLOGRESOLVER_H
 
-#include "ExternC.h"
-#include "SolidSyslogAddress.h"
-#include "SolidSyslogTransport.h"
 #include <stdbool.h>
 #include <stdint.h>
 
+#include "ExternC.h"
+#include "SolidSyslogTransport.h"
+
+struct SolidSyslogAddress;
+
 EXTERN_C_BEGIN
 
     struct SolidSyslogResolver;

diff --git a/Core/Interface/SolidSyslogResolverDefinition.h b/Core/Interface/SolidSyslogResolverDefinition.h
@@ -1,10 +1,13 @@
 #ifndef SOLIDSYSLOGRESOLVERDEFINITION_H
 #define SOLIDSYSLOGRESOLVERDEFINITION_H
 
-#include "SolidSyslogResolver.h"
+#include <stdint.h>
+#include <stdbool.h>
+
 #include "SolidSyslogTransport.h"
+#include "ExternC.h"
 
-#include <stdint.h>
+struct SolidSyslogAddress;
 
 EXTERN_C_BEGIN
 

diff --git a/Core/Interface/SolidSyslogSenderDefinition.h b/Core/Interface/SolidSyslogSenderDefinition.h
@@ -1,7 +1,10 @@
 #ifndef SOLIDSYSLOGSENDERDEFINITION_H
 #define SOLIDSYSLOGSENDERDEFINITION_H
 
-#include "SolidSyslogSender.h"
+#include <stdbool.h>
+#include <stddef.h>
+
+#include "ExternC.h"
 
 EXTERN_C_BEGIN
 

diff --git a/Core/Interface/SolidSyslogStoreDefinition.h b/Core/Interface/SolidSyslogStoreDefinition.h
@@ -1,7 +1,10 @@
 #ifndef SOLIDSYSLOGSTOREDEFINITION_H
 #define SOLIDSYSLOGSTOREDEFINITION_H
 
-#include "SolidSyslogStore.h"
+#include <stdbool.h>
+#include <stddef.h>
+
+#include "ExternC.h"
 
 EXTERN_C_BEGIN
 

diff --git a/Core/Interface/SolidSyslogStream.h b/Core/Interface/SolidSyslogStream.h
@@ -1,12 +1,14 @@
 #ifndef SOLIDSYSLOGSTREAM_H
 #define SOLIDSYSLOGSTREAM_H
 
-#include "ExternC.h"
-#include "SolidSyslogAddress.h"
 #include <stdbool.h>
 #include <stddef.h>
 #include <stdint.h>
 
+#include "ExternC.h"
+
+struct SolidSyslogAddress;
+
 EXTERN_C_BEGIN
 
     /* Signed byte count. Models POSIX ssize_t using a standard-C type for portability

diff --git a/Core/Interface/SolidSyslogStreamDefinition.h b/Core/Interface/SolidSyslogStreamDefinition.h
@@ -1,7 +1,13 @@
 #ifndef SOLIDSYSLOGSTREAMDEFINITION_H
 #define SOLIDSYSLOGSTREAMDEFINITION_H
 
+#include <stdbool.h>
+#include <stddef.h>
+
 #include "SolidSyslogStream.h"
+#include "ExternC.h"
+
+struct SolidSyslogAddress;
 
 EXTERN_C_BEGIN
 

diff --git a/Core/Interface/SolidSyslogStreamSender.h b/Core/Interface/SolidSyslogStreamSender.h
@@ -1,12 +1,11 @@
 #ifndef SOLIDSYSLOG_STREAM_SENDER_H
 #define SOLIDSYSLOG_STREAM_SENDER_H
 
-#include "SolidSyslogEndpoint.h"
-#include "SolidSyslogResolver.h"
-#include "SolidSyslogStream.h"
-
 #include <stdint.h>
 
+#include "SolidSyslogEndpoint.h"
+#include "ExternC.h"
+
 EXTERN_C_BEGIN
 
     struct SolidSyslogSender;

diff --git a/Core/Interface/SolidSyslogStructuredDataDefinition.h b/Core/Interface/SolidSyslogStructuredDataDefinition.h
@@ -1,7 +1,7 @@
 #ifndef SOLIDSYSLOGSTRUCTUREDDATADEFINITION_H
 #define SOLIDSYSLOGSTRUCTUREDDATADEFINITION_H
 
-#include "SolidSyslogStructuredData.h"
+#include "ExternC.h"
 
 EXTERN_C_BEGIN
 

diff --git a/Core/Interface/SolidSyslogSwitchingSender.h b/Core/Interface/SolidSyslogSwitchingSender.h
@@ -1,12 +1,11 @@
 #ifndef SOLIDSYSLOGSWITCHINGSENDER_H
 #define SOLIDSYSLOGSWITCHINGSENDER_H
 
-#include "ExternC.h"
-#include "SolidSyslogSender.h"
-
 #include <stddef.h>
 #include <stdint.h>
 
+#include "ExternC.h"
+
 EXTERN_C_BEGIN
 
     typedef uint8_t (*SolidSyslogSwitchingSenderSelector)(void); // NOLINT(modernize-redundant-void-arg) -- C idiom

diff --git a/Core/Interface/SolidSyslogUdpSender.h b/Core/Interface/SolidSyslogUdpSender.h
@@ -1,11 +1,8 @@
 #ifndef SOLIDSYSLOGUDPSENDER_H
 #define SOLIDSYSLOGUDPSENDER_H
 
-#include "SolidSyslogDatagram.h"
 #include "SolidSyslogEndpoint.h"
-#include "SolidSyslogResolver.h"
-#include "SolidSyslogSender.h"
-#include "SolidSyslogTransport.h"
+#include "ExternC.h"
 
 EXTERN_C_BEGIN
 

diff --git a/Core/Source/SolidSyslog.c b/Core/Source/SolidSyslog.c
@@ -1,14 +1,21 @@
 #include "SolidSyslog.h"
+
+#include <stdbool.h>
+#include <stdint.h>
+#include <stddef.h>
+
 #include "SolidSyslogBuffer.h"
 #include "SolidSyslogConfig.h"
 #include "SolidSyslogStore.h"
 #include "SolidSyslogFormatter.h"
 #include "SolidSyslogMacros.h"
 #include "SolidSyslogSender.h"
 #include "SolidSyslogStructuredData.h"
+#include "SolidSyslogStringFunction.h"
+#include "SolidSyslogTimestamp.h"
 
-#include <stdbool.h>
-#include <stdint.h>
+struct SolidSyslogFormatter;
+struct SolidSyslogStructuredData;
 
 enum
 {

diff --git a/Core/Source/SolidSyslogBlockDevice.c b/Core/Source/SolidSyslogBlockDevice.c
@@ -1,4 +1,8 @@
+#include <stdbool.h>
+#include <stddef.h>
+
 #include "SolidSyslogBlockDeviceDefinition.h"
+#include "SolidSyslogBlockDevice.h"
 
 bool SolidSyslogBlockDevice_Acquire(struct SolidSyslogBlockDevice* device, size_t blockIndex)
 {

diff --git a/Core/Source/SolidSyslogBlockStore.c b/Core/Source/SolidSyslogBlockStore.c
@@ -1,4 +1,7 @@
 #include "SolidSyslogBlockStore.h"
+
+#include <stdbool.h>
+
 #include "BlockSequence.h"
 #include "RecordStore.h"
 #include "SolidSyslog.h"

diff --git a/Core/Source/SolidSyslogBuffer.c b/Core/Source/SolidSyslogBuffer.c
@@ -1,4 +1,8 @@
+#include <stdbool.h>
+#include <stddef.h>
+
 #include "SolidSyslogBufferDefinition.h"
+#include "SolidSyslogBuffer.h"
 
 void SolidSyslogBuffer_Write(struct SolidSyslogBuffer* buffer, const void* data, size_t size)
 {