diff --git a/intern/guardedalloc/intern/mallocn_guarded_impl.cc b/intern/guardedalloc/intern/mallocn_guarded_impl.cc
index 2aaea362764..89a7c1887ee 100644
--- a/intern/guardedalloc/intern/mallocn_guarded_impl.cc
+++ b/intern/guardedalloc/intern/mallocn_guarded_impl.cc
@@ -107,6 +107,8 @@ typedef struct localListBase {
   void *first, *last;
 } localListBase;
 
+namespace {
+
 /* NOTE(@hos): keep this struct aligned (e.g., IRIX/GCC). */
 typedef struct MemHead {
   int tag1;
@@ -137,6 +139,8 @@ static_assert(MEM_MIN_CPP_ALIGNMENT <= sizeof(MemHead), "Bad size of MemHead");
 
 typedef MemHead MemHeadAligned;
 
+}  // namespace
+
 /* #MemHead::flag. */
 enum MemHeadFlag {
   /**
diff --git a/intern/guardedalloc/intern/mallocn_lockfree_impl.cc b/intern/guardedalloc/intern/mallocn_lockfree_impl.cc
index 8d0ae31df98..f6a47242052 100644
--- a/intern/guardedalloc/intern/mallocn_lockfree_impl.cc
+++ b/intern/guardedalloc/intern/mallocn_lockfree_impl.cc
@@ -31,6 +31,8 @@
 
 using namespace mem_guarded::internal;
 
+namespace {
+
 typedef struct MemHead {
   /* Length of allocated memory block. */
   size_t len;
@@ -45,6 +47,8 @@ typedef struct MemHeadAligned {
 static_assert(MEM_MIN_CPP_ALIGNMENT <= alignof(MemHeadAligned), "Bad alignment of MemHeadAligned");
 static_assert(MEM_MIN_CPP_ALIGNMENT <= sizeof(MemHeadAligned), "Bad size of MemHeadAligned");
 
+}  // namespace
+
 static bool malloc_debug_memset = false;
 
 static void (*error_callback)(const char *) = nullptr;
diff --git a/source/blender/blenkernel/intern/movieclip.cc b/source/blender/blenkernel/intern/movieclip.cc
index 561e5c1a3cd..c35aa55ee73 100644
--- a/source/blender/blenkernel/intern/movieclip.cc
+++ b/source/blender/blenkernel/intern/movieclip.cc
@@ -465,11 +465,15 @@ static void get_proxy_filepath(const MovieClip *clip,
 
 #ifdef WITH_OPENEXR
 
+namespace {
+
 struct MultilayerConvertContext {
   float *combined_pass;
   int num_combined_channels;
 };
 
+}  // namespace
+
 static void *movieclip_convert_multilayer_add_view(void * /*ctx_v*/, const char * /*view_name*/)
 {
   return nullptr;
diff --git a/source/blender/blenkernel/intern/studiolight.cc b/source/blender/blenkernel/intern/studiolight.cc
index d61345334a2..f672674dfd6 100644
--- a/source/blender/blenkernel/intern/studiolight.cc
+++ b/source/blender/blenkernel/intern/studiolight.cc
@@ -274,6 +274,8 @@ static void direction_to_equirect(float r[2], const float dir[3])
   r[1] = (acosf(dir[2] / 1.0) - M_PI) / -M_PI;
 }
 
+namespace {
+
 struct MultilayerConvertContext {
   int num_diffuse_channels;
   float *diffuse_pass;
@@ -281,6 +283,8 @@ struct MultilayerConvertContext {
   float *specular_pass;
 };
 
+}  // namespace
+
 static void *studiolight_multilayer_addview(void * /*base*/, const char * /*view_name*/)
 {
   return nullptr;
diff --git a/source/blender/blenlib/intern/polyfill_2d.cc b/source/blender/blenlib/intern/polyfill_2d.cc
index baf7d191c76..28c4f6b7311 100644
--- a/source/blender/blenlib/intern/polyfill_2d.cc
+++ b/source/blender/blenlib/intern/polyfill_2d.cc
@@ -65,6 +65,8 @@
 #  include "BLI_time_utildefines.h"
 #endif
 
+namespace {
+
 using eSign = int8_t;
 
 #ifdef USE_KDTREE
@@ -147,6 +149,8 @@ struct PolyFill {
 #endif
 };
 
+}  // namespace
+
 /* Based on LIBGDX 2013-11-28, APACHE 2.0 licensed. */
 
 static void pf_coord_sign_calc(const PolyFill *pf, PolyIndex *pi);
diff --git a/source/blender/blenlib/intern/scanfill.cc b/source/blender/blenlib/intern/scanfill.cc
index 09aadd7b22b..5e3acc8d352 100644
--- a/source/blender/blenlib/intern/scanfill.cc
+++ b/source/blender/blenlib/intern/scanfill.cc
@@ -34,6 +34,8 @@
 
 #include "BLI_strict_flags.h" /* IWYU pragma: keep. Keep last. */
 
+namespace {
+
 /* local types */
 struct PolyFill {
   uint edges, verts;
@@ -47,6 +49,8 @@ struct ScanFillVertLink {
   ScanFillEdge *edge_first, *edge_last;
 };
 
+}  // namespace
+
 /* Local functions. */
 
 #define SF_EPSILON 0.00003f
diff --git a/source/blender/bmesh/operators/bmo_join_triangles.cc b/source/blender/bmesh/operators/bmo_join_triangles.cc
index 20a9370d233..2272e93ca7e 100644
--- a/source/blender/bmesh/operators/bmo_join_triangles.cc
+++ b/source/blender/bmesh/operators/bmo_join_triangles.cc
@@ -268,6 +268,9 @@ static void bm_edge_to_quad_verts(const BMEdge *e, const BMVert *r_v_quad[4])
  * \{ */
 
 /** Cache custom-data delimiters. */
+
+namespace {
+
 struct DelimitData_CD {
   int cd_type;
   int cd_size;
@@ -291,6 +294,8 @@ struct DelimitData {
   int cdata_len;
 };
 
+}  // namespace
+
 /** Determines if the loop custom-data is contiguous. */
 static bool bm_edge_is_contiguous_loop_cd_all(const BMEdge *e, const DelimitData_CD *delimit_data)
 {
diff --git a/source/blender/bmesh/tools/bmesh_decimate_dissolve.cc b/source/blender/bmesh/tools/bmesh_decimate_dissolve.cc
index 0b27cc18806..0daf9788cf5 100644
--- a/source/blender/bmesh/tools/bmesh_decimate_dissolve.cc
+++ b/source/blender/bmesh/tools/bmesh_decimate_dissolve.cc
@@ -25,7 +25,16 @@
 
 #define COST_INVALID FLT_MAX
 
-struct DelimitData;
+namespace {
+
+struct DelimitData {
+  int cd_loop_type;
+  int cd_loop_size;
+  int cd_loop_offset;
+  int cd_loop_offset_end;
+};
+
+}  // namespace
 
 static bool bm_edge_is_delimiter(const BMEdge *e,
                                  const BMO_Delimit delimit,
@@ -64,13 +73,6 @@ static float bm_vert_edge_face_angle(BMVert *v,
 #undef ANGLE_TO_UNIT
 }
 
-struct DelimitData {
-  int cd_loop_type;
-  int cd_loop_size;
-  int cd_loop_offset;
-  int cd_loop_offset_end;
-};
-
 static bool bm_edge_is_contiguous_loop_cd_all(const BMEdge *e, const DelimitData *delimit_data)
 {
   int cd_loop_offset;
diff --git a/source/blender/editors/curve/editcurve_undo.cc b/source/blender/editors/curve/editcurve_undo.cc
index 82e651f0666..f1446a47284 100644
--- a/source/blender/editors/curve/editcurve_undo.cc
+++ b/source/blender/editors/curve/editcurve_undo.cc
@@ -46,6 +46,8 @@ static CLG_LogRef LOG = {"ed.undo.curve"};
 /** \name Undo Conversion
  * \{ */
 
+namespace {
+
 struct UndoCurve {
   ListBase nubase;
   int actvert;
@@ -72,6 +74,8 @@ struct UndoCurve {
   size_t undo_size;
 };
 
+}  // namespace
+
 static void undocurve_to_editcurve(Main *bmain, UndoCurve *ucu, Curve *cu, short *r_shapenr)
 {
   ListBase *undobase = &ucu->nubase;
diff --git a/source/blender/editors/gizmo_library/gizmo_types/cage2d_gizmo.cc b/source/blender/editors/gizmo_library/gizmo_types/cage2d_gizmo.cc
index 1dfeb665cfa..96ed75def3c 100644
--- a/source/blender/editors/gizmo_library/gizmo_types/cage2d_gizmo.cc
+++ b/source/blender/editors/gizmo_library/gizmo_types/cage2d_gizmo.cc
@@ -992,6 +992,8 @@ static int gizmo_cage2d_test_select(bContext *C, wmGizmo *gz, const int mval[2])
   return -1;
 }
 
+namespace {
+
 struct RectTransformInteraction {
   float orig_mouse[2];
   float orig_matrix_offset[4][4];
@@ -1000,6 +1002,8 @@ struct RectTransformInteraction {
   bool use_temp_uniform;
 };
 
+}  // namespace
+
 static int gizmo_cage2d_transform_flag_get(const wmGizmo *gz)
 {
   RectTransformInteraction *data = static_cast<RectTransformInteraction *>(gz->interaction_data);
diff --git a/source/blender/editors/gizmo_library/gizmo_types/cage3d_gizmo.cc b/source/blender/editors/gizmo_library/gizmo_types/cage3d_gizmo.cc
index 0637cc0a53c..da9c224fee2 100644
--- a/source/blender/editors/gizmo_library/gizmo_types/cage3d_gizmo.cc
+++ b/source/blender/editors/gizmo_library/gizmo_types/cage3d_gizmo.cc
@@ -429,12 +429,16 @@ static int gizmo_cage3d_get_cursor(wmGizmo *gz)
   return WM_CURSOR_DEFAULT;
 }
 
+namespace {
+
 struct RectTransformInteraction {
   float orig_mouse[3];
   float orig_matrix_offset[4][4];
   float orig_matrix_final_no_offset[4][4];
 };
 
+}  // namespace
+
 static void gizmo_cage3d_setup(wmGizmo *gz)
 {
   gz->flag |= /* WM_GIZMO_DRAW_MODAL | */ /* TODO */
diff --git a/source/blender/editors/interface/view2d/view2d_gizmo_navigate.cc b/source/blender/editors/interface/view2d/view2d_gizmo_navigate.cc
index 2be4e27209a..8bb2f339597 100644
--- a/source/blender/editors/interface/view2d/view2d_gizmo_navigate.cc
+++ b/source/blender/editors/interface/view2d/view2d_gizmo_navigate.cc
@@ -39,6 +39,8 @@
 /* How much mini buttons offset from the primary. */
 #define GIZMO_MINI_OFFSET_FAC 0.38f
 
+namespace {
+
 enum {
   GZ_INDEX_MOVE = 0,
   GZ_INDEX_ZOOM = 1,
@@ -52,6 +54,16 @@ struct NavigateGizmoInfo {
   uint icon;
 };
 
+struct NavigateWidgetGroup {
+  wmGizmo *gz_array[GZ_INDEX_TOTAL];
+  /* Store the view state to check for changes. */
+  struct {
+    rcti rect_visible;
+  } state;
+};
+
+}  // namespace
+
 static NavigateGizmoInfo g_navigate_params_for_space_image[GZ_INDEX_TOTAL] = {
     {
         "IMAGE_OT_view_pan",
@@ -104,14 +116,6 @@ static NavigateGizmoInfo *navigate_params_from_space_type(short space_type)
   }
 }
 
-struct NavigateWidgetGroup {
-  wmGizmo *gz_array[GZ_INDEX_TOTAL];
-  /* Store the view state to check for changes. */
-  struct {
-    rcti rect_visible;
-  } state;
-};
-
 static bool WIDGETGROUP_navigate_poll(const bContext *C, wmGizmoGroupType * /*gzgt*/)
 {
   if ((U.uiflag & USER_SHOW_GIZMO_NAVIGATE) == 0) {
diff --git a/source/blender/editors/sculpt_paint/paint_curve_undo.cc b/source/blender/editors/sculpt_paint/paint_curve_undo.cc
index 2d4aa036256..3213a191e95 100644
--- a/source/blender/editors/sculpt_paint/paint_curve_undo.cc
+++ b/source/blender/editors/sculpt_paint/paint_curve_undo.cc
@@ -31,12 +31,16 @@
 /** \name Undo Conversion
  * \{ */
 
+namespace {
+
 struct UndoCurve {
   PaintCurvePoint *points; /* points of curve */
   int tot_points;
   int add_index;
 };
 
+}  // namespace
+
 static void undocurve_from_paintcurve(UndoCurve *uc, const PaintCurve *pc)
 {
   BLI_assert(BLI_array_is_zeroed(uc, 1));
diff --git a/source/blender/editors/sculpt_paint/sculpt_uv.cc b/source/blender/editors/sculpt_paint/sculpt_uv.cc
index b771bcbfe05..2252774ff2e 100644
--- a/source/blender/editors/sculpt_paint/sculpt_uv.cc
+++ b/source/blender/editors/sculpt_paint/sculpt_uv.cc
@@ -46,6 +46,8 @@
 
 #include "UI_view2d.hh"
 
+namespace {
+
 enum eBrushUVSculptTool {
   UV_SCULPT_BRUSH_TYPE_GRAB = 0,
   UV_SCULPT_BRUSH_TYPE_RELAX = 1,
@@ -145,6 +147,8 @@ struct UvSculptData {
   float uv_base_offset[2];
 };
 
+}  // namespace
+
 static void apply_sculpt_data_constraints(UvSculptData *sculptdata, float uv[2])
 {
   if (!sculptdata->constrain_to_bounds) {
diff --git a/source/blender/editors/space_clip/clip_ops.cc b/source/blender/editors/space_clip/clip_ops.cc
index 9e31f88772e..99f965ee6ee 100644
--- a/source/blender/editors/space_clip/clip_ops.cc
+++ b/source/blender/editors/space_clip/clip_ops.cc
@@ -363,6 +363,8 @@ void CLIP_OT_reload(wmOperatorType *ot)
 /** \name View Pan Operator
  * \{ */
 
+namespace {
+
 struct ViewPanData {
   float x, y;
   float xof, yof, xorig, yorig;
@@ -371,6 +373,8 @@ struct ViewPanData {
   float *vec;
 };
 
+}  // namespace
+
 static void view_pan_init(bContext *C, wmOperator *op, const wmEvent *event)
 {
   wmWindow *win = CTX_wm_window(C);
@@ -536,6 +540,8 @@ void CLIP_OT_view_pan(wmOperatorType *ot)
 /** \name View Zoom Operator
  * \{ */
 
+namespace {
+
 struct ViewZoomData {
   float x, y;
   float zoom;
@@ -546,6 +552,8 @@ struct ViewZoomData {
   bool own_cursor;
 };
 
+}  // namespace
+
 static void view_zoom_init(bContext *C, wmOperator *op, const wmEvent *event)
 {
   wmWindow *win = CTX_wm_window(C);
diff --git a/source/blender/editors/space_image/image_buttons.cc b/source/blender/editors/space_image/image_buttons.cc
index 4b0c8a7b7f0..c4aa6ab034a 100644
--- a/source/blender/editors/space_image/image_buttons.cc
+++ b/source/blender/editors/space_image/image_buttons.cc
@@ -698,7 +698,6 @@ static void uiblock_layer_pass_buttons(uiLayout *layout,
   }
 }
 
-/* Prevent naming collision. */
 namespace {
 
 struct RNAUpdateCb {
diff --git a/source/blender/editors/space_image/image_ops.cc b/source/blender/editors/space_image/image_ops.cc
index 2d22b0d51b0..63b3f805766 100644
--- a/source/blender/editors/space_image/image_ops.cc
+++ b/source/blender/editors/space_image/image_ops.cc
@@ -357,6 +357,8 @@ static bool space_image_main_area_not_uv_brush_poll(bContext *C)
 /** \name View Pan Operator
  * \{ */
 
+namespace {
+
 struct ViewPanData {
   float x, y;
   float xof, yof;
@@ -364,6 +366,8 @@ struct ViewPanData {
   bool own_cursor;
 };
 
+}  // namespace
+
 static void image_view_pan_init(bContext *C, wmOperator *op, const wmEvent *event)
 {
   wmWindow *win = CTX_wm_window(C);
@@ -504,6 +508,8 @@ void IMAGE_OT_view_pan(wmOperatorType *ot)
 /** \name View Zoom Operator
  * \{ */
 
+namespace {
+
 struct ViewZoomData {
   float origx, origy;
   float zoom;
@@ -520,6 +526,8 @@ struct ViewZoomData {
   ARegion *region;
 };
 
+}  // namespace
+
 static void image_view_zoom_init(bContext *C, wmOperator *op, const wmEvent *event)
 {
   wmWindow *win = CTX_wm_window(C);
diff --git a/source/blender/editors/space_view3d/view3d_gizmo_navigate.cc b/source/blender/editors/space_view3d/view3d_gizmo_navigate.cc
index af1526cc565..33e600d830d 100644
--- a/source/blender/editors/space_view3d/view3d_gizmo_navigate.cc
+++ b/source/blender/editors/space_view3d/view3d_gizmo_navigate.cc
@@ -42,6 +42,8 @@
 /* Margin around the smaller buttons. */
 #define GIZMO_MINI_OFFSET 2.0f
 
+namespace {
+
 enum {
   GZ_INDEX_MOVE = 0,
   GZ_INDEX_ROTATE = 1,
@@ -68,6 +70,22 @@ struct NavigateGizmoInfo {
   void (*op_prop_fn)(PointerRNA *ptr);
 };
 
+struct NavigateWidgetGroup {
+  wmGizmo *gz_array[GZ_INDEX_TOTAL];
+  /* Store the view state to check for changes. */
+  struct {
+    rcti rect_visible;
+    struct {
+      char is_persp;
+      bool is_camera;
+      char viewlock;
+      char cameralock;
+    } rv3d;
+  } state;
+};
+
+}  // namespace
+
 static void navigate_context_toggle_camera_lock_init(PointerRNA *ptr)
 {
   RNA_string_set(ptr, "data_path", "space_data.lock_camera");
@@ -130,20 +148,6 @@ static NavigateGizmoInfo g_navigate_params[GZ_INDEX_TOTAL] = {
     },
 };
 
-struct NavigateWidgetGroup {
-  wmGizmo *gz_array[GZ_INDEX_TOTAL];
-  /* Store the view state to check for changes. */
-  struct {
-    rcti rect_visible;
-    struct {
-      char is_persp;
-      bool is_camera;
-      char viewlock;
-      char cameralock;
-    } rv3d;
-  } state;
-};
-
 static bool WIDGETGROUP_navigate_poll(const bContext *C, wmGizmoGroupType * /*gzgt*/)
 {
   View3D *v3d = CTX_wm_view3d(C);
diff --git a/source/blender/editors/transform/transform_convert_sequencer.cc b/source/blender/editors/transform/transform_convert_sequencer.cc
index 5b2983923a1..2bc2f59255a 100644
--- a/source/blender/editors/transform/transform_convert_sequencer.cc
+++ b/source/blender/editors/transform/transform_convert_sequencer.cc
@@ -40,6 +40,8 @@ namespace blender::ed::transform {
 #define STRIP_EDGE_PAN_DELAY 1.0f
 #define STRIP_EDGE_PAN_ZOOM_INFLUENCE 0.5f
 
+namespace {
+
 /** Used for sequencer transform. */
 struct TransDataSeq {
   Strip *strip;
@@ -68,6 +70,8 @@ struct TransSeq {
   VectorSet<Strip *> time_dependent_strips;
 };
 
+}  // namespace
+
 /* -------------------------------------------------------------------- */
 /** \name Sequencer Transform Creation
  * \{ */
diff --git a/source/blender/editors/transform/transform_convert_sequencer_image.cc b/source/blender/editors/transform/transform_convert_sequencer_image.cc
index 29f8c22ad0c..c2f74645a87 100644
--- a/source/blender/editors/transform/transform_convert_sequencer_image.cc
+++ b/source/blender/editors/transform/transform_convert_sequencer_image.cc
@@ -31,6 +31,8 @@
 
 namespace blender::ed::transform {
 
+namespace {
+
 /** Used for sequencer transform. */
 struct TransDataSeq {
   Strip *strip;
@@ -40,6 +42,8 @@ struct TransDataSeq {
   float orig_rotation;
 };
 
+}  // namespace
+
 static TransData *SeqToTransData(const Scene *scene,
                                  Strip *strip,
                                  TransData *td,
diff --git a/source/blender/editors/uvedit/uvedit_path.cc b/source/blender/editors/uvedit/uvedit_path.cc
index e690e409567..c91640c8f10 100644
--- a/source/blender/editors/uvedit/uvedit_path.cc
+++ b/source/blender/editors/uvedit/uvedit_path.cc
@@ -55,6 +55,8 @@ using blender::Vector;
 /** \name Path Select Struct & Properties
  * \{ */
 
+namespace {
+
 struct PathSelectParams {
   /** ensure the active element is the last selected item (handy for picking) */
   bool track_active;
@@ -70,6 +72,8 @@ struct UserData_UV {
   BMUVOffsets offsets;
 };
 
+}  // namespace
+
 static void path_select_properties(wmOperatorType *ot)
 {
   RNA_def_boolean(ot->srna,
diff --git a/source/blender/editors/uvedit/uvedit_smart_stitch.cc b/source/blender/editors/uvedit/uvedit_smart_stitch.cc
index 3d818d28a5a..d025586227f 100644
--- a/source/blender/editors/uvedit/uvedit_smart_stitch.cc
+++ b/source/blender/editors/uvedit/uvedit_smart_stitch.cc
@@ -60,6 +60,8 @@ using blender::Vector;
 
 /* ********************** smart stitch operator *********************** */
 
+namespace {
+
 /* object that stores display data for previewing before confirming stitching */
 struct StitchPreviewer {
   /* here we'll store the preview triangle indices of the mesh */
@@ -231,6 +233,8 @@ struct StitchStateInit {
   UvElementID *to_select;
 };
 
+}  // namespace
+
 /* constructor */
 static StitchPreviewer *stitch_preview_init()
 {
diff --git a/source/blender/modifiers/intern/MOD_laplaciandeform.cc b/source/blender/modifiers/intern/MOD_laplaciandeform.cc
index 7056d7e99aa..0616f9c5b33 100644
--- a/source/blender/modifiers/intern/MOD_laplaciandeform.cc
+++ b/source/blender/modifiers/intern/MOD_laplaciandeform.cc
@@ -49,7 +49,6 @@ enum {
   LAPDEFORM_SYSTEM_CHANGE_NOT_VALID_GROUP,
 };
 
-/* Prevent naming collision. */
 namespace {
 
 struct LaplacianSystem {
diff --git a/source/blender/modifiers/intern/MOD_laplaciansmooth.cc b/source/blender/modifiers/intern/MOD_laplaciansmooth.cc
index 4090b3989a6..a4b8a9799e3 100644
--- a/source/blender/modifiers/intern/MOD_laplaciansmooth.cc
+++ b/source/blender/modifiers/intern/MOD_laplaciansmooth.cc
@@ -31,7 +31,6 @@
 
 #include "eigen_capi.h"
 
-/* Prevent naming collision. */
 namespace {
 
 struct LaplacianSystem {