diff --git a/source/blender/animrig/intern/action.cc b/source/blender/animrig/intern/action.cc
index 75d71fe8c87..e96f6a62e06 100644
--- a/source/blender/animrig/intern/action.cc
+++ b/source/blender/animrig/intern/action.cc
@@ -172,7 +172,7 @@ static void array_shift_range(
   BLI_assert(to <= num + range_start - range_end);
   UNUSED_VARS_NDEBUG(num);
 
-  if (range_start == range_end || range_start == to) {
+  if (ELEM(range_start, range_end, to)) {
     return;
   }
 
@@ -1928,7 +1928,7 @@ ID *action_slot_get_id_best_guess(Main &bmain, Slot &slot, ID *primary_id)
 {
   blender::Span<ID *> users = slot.users(bmain);
   if (users.is_empty()) {
-    return 0;
+    return nullptr;
   }
   if (users.contains(primary_id)) {
     return primary_id;
diff --git a/source/blender/blenloader/BLO_read_write.hh b/source/blender/blenloader/BLO_read_write.hh
index 5bbd36a2ab2..56d6d5443fb 100644
--- a/source/blender/blenloader/BLO_read_write.hh
+++ b/source/blender/blenloader/BLO_read_write.hh
@@ -86,7 +86,7 @@ struct Main;
 /**
  * Mapping between names and ids.
  */
-int BLO_get_struct_id_by_name(BlendWriter *writer, const char *struct_name);
+int BLO_get_struct_id_by_name(const BlendWriter *writer, const char *struct_name);
 #define BLO_get_struct_id(writer, struct_name) SDNA_TYPE_FROM_STRUCT(struct_name)
 
 /**
@@ -146,7 +146,7 @@ void BLO_write_struct_array_at_address_by_id(
  * Write struct list.
  */
 void BLO_write_struct_list_by_name(BlendWriter *writer, const char *struct_name, ListBase *list);
-void BLO_write_struct_list_by_id(BlendWriter *writer, int struct_id, ListBase *list);
+void BLO_write_struct_list_by_id(BlendWriter *writer, int struct_id, const ListBase *list);
 #define BLO_write_struct_list(writer, struct_name, list_ptr) \
   BLO_write_struct_list_by_id(writer, BLO_get_struct_id(writer, struct_name), list_ptr)
 
diff --git a/source/blender/blenloader/intern/writefile.cc b/source/blender/blenloader/intern/writefile.cc
index d433f2e91b6..b5cedc1d1ab 100644
--- a/source/blender/blenloader/intern/writefile.cc
+++ b/source/blender/blenloader/intern/writefile.cc
@@ -1874,7 +1874,7 @@ void BLO_write_struct_array_at_address_by_id(
   writestruct_at_address_nr(writer->wd, BLO_CODE_DATA, struct_id, array_size, address, data_ptr);
 }
 
-void BLO_write_struct_list_by_id(BlendWriter *writer, int struct_id, ListBase *list)
+void BLO_write_struct_list_by_id(BlendWriter *writer, int struct_id, const ListBase *list)
 {
   writelist_nr(writer->wd, BLO_CODE_DATA, struct_id, list);
 }
@@ -1894,7 +1894,7 @@ void blo_write_id_struct(BlendWriter *writer, int struct_id, const void *id_addr
   writestruct_at_address_nr(writer->wd, GS(id->name), struct_id, 1, id_address, id);
 }
 
-int BLO_get_struct_id_by_name(BlendWriter *writer, const char *struct_name)
+int BLO_get_struct_id_by_name(const BlendWriter *writer, const char *struct_name)
 {
   int struct_id = DNA_struct_find_with_alias(writer->wd->sdna, struct_name);
   return struct_id;
diff --git a/source/blender/editors/animation/anim_filter_test.cc b/source/blender/editors/animation/anim_filter_test.cc
index 1aae9892912..20e456972de 100644
--- a/source/blender/editors/animation/anim_filter_test.cc
+++ b/source/blender/editors/animation/anim_filter_test.cc
@@ -95,12 +95,12 @@ TEST_F(ActionFilterTest, slots_expanded_or_not)
   ASSERT_NE(nullptr, fcu_cube_loc_y);
 
   /* Mock an bAnimContext for the Animation editor, with the above Animation showing. */
-  SpaceAction saction = {0};
+  SpaceAction saction = {nullptr};
   saction.action = action;
   saction.action_slot_handle = slot_cube.handle;
   saction.ads.filterflag = ADS_FILTER_ALL_SLOTS;
 
-  bAnimContext ac = {0};
+  bAnimContext ac = {nullptr};
   ac.bmain = bmain;
   ac.datatype = ANIMCONT_ACTION;
   ac.data = action;
@@ -249,12 +249,12 @@ TEST_F(ActionFilterTest, layered_action_active_fcurves)
   fcurve_other->flag &= ~FCURVE_ACTIVE;
 
   /* Mock an bAnimContext for the Action editor. */
-  SpaceAction saction = {0};
+  SpaceAction saction = {nullptr};
   saction.action = action;
   saction.action_slot_handle = slot_cube.handle;
   saction.ads.filterflag = ADS_FILTER_ALL_SLOTS;
 
-  bAnimContext ac = {0};
+  bAnimContext ac = {nullptr};
   ac.bmain = bmain;
   ac.datatype = ANIMCONT_ACTION;
   ac.data = action;
diff --git a/source/blender/editors/grease_pencil/intern/grease_pencil_image_render.cc b/source/blender/editors/grease_pencil/intern/grease_pencil_image_render.cc
index b2ea0652608..59dec75d0cb 100644
--- a/source/blender/editors/grease_pencil/intern/grease_pencil_image_render.cc
+++ b/source/blender/editors/grease_pencil/intern/grease_pencil_image_render.cc
@@ -551,7 +551,7 @@ void draw_grease_pencil_strokes(const RegionView3D &rv3d,
                                                            mat->gp_style->mode) :
                                                        GP_MATERIAL_MODE_LINE;
 
-    if (mat == 0 || (mat->gp_style->flag & GP_MATERIAL_HIDE)) {
+    if (mat == nullptr || (mat->gp_style->flag & GP_MATERIAL_HIDE)) {
       return;
     }
 
diff --git a/source/blender/editors/grease_pencil/intern/grease_pencil_utils.cc b/source/blender/editors/grease_pencil/intern/grease_pencil_utils.cc
index a8f38c18782..e19638a71be 100644
--- a/source/blender/editors/grease_pencil/intern/grease_pencil_utils.cc
+++ b/source/blender/editors/grease_pencil/intern/grease_pencil_utils.cc
@@ -68,9 +68,7 @@ DrawingPlacement::DrawingPlacement(const Scene &scene,
   }
 
   /* Account for layer transform. */
-  if (scene.toolsettings->gp_sculpt.lock_axis != GP_LOCKAXIS_VIEW &&
-      scene.toolsettings->gp_sculpt.lock_axis != GP_LOCKAXIS_CURSOR)
-  {
+  if (!ELEM(scene.toolsettings->gp_sculpt.lock_axis, GP_LOCKAXIS_VIEW, GP_LOCKAXIS_CURSOR)) {
     /* Use the transpose inverse for normal. */
     placement_normal_ = math::transform_direction(math::transpose(world_space_to_layer_space_),
                                                   placement_normal_);
@@ -154,7 +152,7 @@ DrawingPlacement::DrawingPlacement(const Scene &scene,
   }
 
   /* Account for layer transform. */
-  if (reproject_mode != ReprojectMode::View && reproject_mode != ReprojectMode::Cursor) {
+  if (!ELEM(reproject_mode, ReprojectMode::View, ReprojectMode::Cursor)) {
     /* Use the transpose inverse for normal. */
     placement_normal_ = math::transform_direction(math::transpose(world_space_to_layer_space_),
                                                   placement_normal_);
diff --git a/source/blender/editors/interface/eyedroppers/eyedropper_grease_pencil_color.cc b/source/blender/editors/interface/eyedroppers/eyedropper_grease_pencil_color.cc
index b720975f3c6..737bd7df500 100644
--- a/source/blender/editors/interface/eyedroppers/eyedropper_grease_pencil_color.cc
+++ b/source/blender/editors/interface/eyedroppers/eyedropper_grease_pencil_color.cc
@@ -323,7 +323,7 @@ static void eyedropper_gpencil_color_set(bContext *C,
   /* Convert from linear rgb space to display space because palette and brush colors are in display
    *  space, and this conversion is needed to undo the conversion to linear performed by
    *  eyedropper_color_sample_fl. */
-  if ((eye->display) && (eye->mode == EyeMode::Palette || eye->mode == EyeMode::Brush)) {
+  if (eye->display && ELEM(eye->mode, EyeMode::Palette, EyeMode::Brush)) {
     IMB_colormanagement_scene_linear_to_display_v3(col_conv, eye->display);
   }
 
diff --git a/source/blender/editors/interface/interface_draw.cc b/source/blender/editors/interface/interface_draw.cc
index 544e84b77a6..4b5a0ca0977 100644
--- a/source/blender/editors/interface/interface_draw.cc
+++ b/source/blender/editors/interface/interface_draw.cc
@@ -1976,7 +1976,7 @@ void ui_draw_but_CURVEPROFILE(ARegion *region,
     BLI_polyfill_calc(table_coords, tot_points, -1, tri_indices);
 
     /* Draw the triangles for the profile fill. */
-    immUniformColor3ubvAlpha((const uchar *)wcol->item, 128);
+    immUniformColor3ubvAlpha(wcol->item, 128);
     GPU_blend(GPU_BLEND_ALPHA);
     GPU_polygon_smooth(false);
     immBegin(GPU_PRIM_TRIS, 3 * tot_triangles);
diff --git a/source/blender/editors/interface/interface_icons.cc b/source/blender/editors/interface/interface_icons.cc
index 25d2ec7e914..51142620c7f 100644
--- a/source/blender/editors/interface/interface_icons.cc
+++ b/source/blender/editors/interface/interface_icons.cc
@@ -1378,7 +1378,7 @@ static void svg_replace_color_attributes(std::string &svg,
         "{:02x}{:02x}{:02x}{:02x}", color[0], color[1], color[2], color[3]);
 
     size_t att_start = start;
-    while (1) {
+    while (true) {
       constexpr static blender::StringRef key = "fill=\"";
       att_start = svg.find(key, att_start);
       if (att_start == std::string::npos || att_start > end) {
@@ -1392,7 +1392,7 @@ static void svg_replace_color_attributes(std::string &svg,
     }
 
     att_start = start;
-    while (1) {
+    while (true) {
       constexpr static blender::StringRef key = "fill:";
       att_start = svg.find(key, att_start);
       if (att_start == std::string::npos || att_start > end) {
@@ -1413,7 +1413,7 @@ static void icon_source_edit_cb(std::string &svg)
 
   /* Scan string, processing only groups with our keyword ids. */
 
-  while (1) {
+  while (true) {
     /* Look for a blender id, quick exit if not found. */
     constexpr static blender::StringRef key = "id=\"";
     const size_t id_start = svg.find(key + "blender_", g_start);
diff --git a/source/blender/editors/sculpt_paint/grease_pencil_fill.cc b/source/blender/editors/sculpt_paint/grease_pencil_fill.cc
index 0a224f98fd3..23f58e9648b 100644
--- a/source/blender/editors/sculpt_paint/grease_pencil_fill.cc
+++ b/source/blender/editors/sculpt_paint/grease_pencil_fill.cc
@@ -884,7 +884,7 @@ static rctf get_boundary_bounds(const ARegion &region,
       /* Check if the color is visible. */
       const int material_index = materials[curve_i];
       Material *mat = BKE_object_material_get(const_cast<Object *>(&object), material_index + 1);
-      if (mat == 0 || (mat->gp_style->flag & GP_MATERIAL_HIDE)) {
+      if (mat == nullptr || (mat->gp_style->flag & GP_MATERIAL_HIDE)) {
         return;
       }
 
diff --git a/source/blender/editors/sculpt_paint/sculpt.cc b/source/blender/editors/sculpt_paint/sculpt.cc
index 8250d127cba..eb24fa2511f 100644
--- a/source/blender/editors/sculpt_paint/sculpt.cc
+++ b/source/blender/editors/sculpt_paint/sculpt.cc
@@ -1321,7 +1321,7 @@ void restore_position_from_undo_step(const Depsgraph &depsgraph, Object &object)
                 /* Because brush deformation is calculated for the evaluated deformed positions,
                  * the translations have to be transformed to the original space. */
                 apply_crazyspace_to_translations(ss.deform_imats, verts, tls.translations);
-                if (active_key == nullptr || mesh.key->refkey == active_key) {
+                if (ELEM(active_key, nullptr, mesh.key->refkey)) {
                   /* We only ever want to propagate changes back to the base mesh if we either have
                    * no shape key active, or we are working on the basis shape key.
                    * See #126199 for more information. */
diff --git a/source/blender/gpu/GPU_batch.hh b/source/blender/gpu/GPU_batch.hh
index f80d1e954d7..d4fa6216edc 100644
--- a/source/blender/gpu/GPU_batch.hh
+++ b/source/blender/gpu/GPU_batch.hh
@@ -425,7 +425,7 @@ void GPU_batch_draw_parameter_get(blender::gpu::Batch *batch,
 /**
  * Return vertex range for this #blender::gpu::Batch when using primitive expansions.
  */
-blender::IndexRange GPU_batch_draw_expanded_parameter_get(blender::gpu::Batch *batch,
+blender::IndexRange GPU_batch_draw_expanded_parameter_get(const blender::gpu::Batch *batch,
                                                           GPUPrimType expanded_prim_type,
                                                           int vertex_count,
                                                           int vertex_first);
diff --git a/source/blender/gpu/intern/gpu_batch.cc b/source/blender/gpu/intern/gpu_batch.cc
index f3e63f67481..3bcda577f25 100644
--- a/source/blender/gpu/intern/gpu_batch.cc
+++ b/source/blender/gpu/intern/gpu_batch.cc
@@ -343,7 +343,7 @@ void GPU_batch_draw_parameter_get(Batch *gpu_batch,
   *r_instance_count = i_count;
 }
 
-blender::IndexRange GPU_batch_draw_expanded_parameter_get(blender::gpu::Batch *batch,
+blender::IndexRange GPU_batch_draw_expanded_parameter_get(const blender::gpu::Batch *batch,
                                                           GPUPrimType expanded_prim_type,
                                                           int vertex_count,
                                                           int vertex_first)
diff --git a/source/blender/gpu/opengl/gl_storage_buffer.cc b/source/blender/gpu/opengl/gl_storage_buffer.cc
index e97bbd452e5..9acc67c3a04 100644
--- a/source/blender/gpu/opengl/gl_storage_buffer.cc
+++ b/source/blender/gpu/opengl/gl_storage_buffer.cc
@@ -232,7 +232,7 @@ void GLStorageBuf::read(void *data)
     /* Repeat until the data is ready. */
   }
   glDeleteSync(read_fence_);
-  read_fence_ = 0;
+  read_fence_ = nullptr;
 
   memcpy(data, persistent_ptr_, size_in_bytes_);
 }
diff --git a/source/blender/imbuf/intern/openexr/openexr_api.cpp b/source/blender/imbuf/intern/openexr/openexr_api.cpp
index fa5c7dc35b8..70bfcae2c43 100644
--- a/source/blender/imbuf/intern/openexr/openexr_api.cpp
+++ b/source/blender/imbuf/intern/openexr/openexr_api.cpp
@@ -1567,7 +1567,7 @@ static int imb_exr_split_channel_name(ExrChannel *echan,
   return 1;
 }
 
-static ExrLayer *imb_exr_get_layer(ListBase *lb, char *layname)
+static ExrLayer *imb_exr_get_layer(ListBase *lb, const char *layname)
 {
   ExrLayer *lay = (ExrLayer *)BLI_findstring(lb, layname, offsetof(ExrLayer, name));
 
@@ -1580,7 +1580,7 @@ static ExrLayer *imb_exr_get_layer(ListBase *lb, char *layname)
   return lay;
 }
 
-static ExrPass *imb_exr_get_pass(ListBase *lb, char *passname)
+static ExrPass *imb_exr_get_pass(ListBase *lb, const char *passname)
 {
   ExrPass *pass = (ExrPass *)BLI_findstring(lb, passname, offsetof(ExrPass, name));
 
diff --git a/source/blender/imbuf/intern/scaling.cc b/source/blender/imbuf/intern/scaling.cc
index fa4851e00ee..dcd2248828f 100644
--- a/source/blender/imbuf/intern/scaling.cc
+++ b/source/blender/imbuf/intern/scaling.cc
@@ -776,8 +776,7 @@ static void scale_bilinear_func(
   });
 }
 
-bool IMB_scale(
-    ImBuf *ibuf, unsigned int newx, unsigned int newy, IMBScaleFilter filter, bool threaded)
+bool IMB_scale(ImBuf *ibuf, uint newx, uint newy, IMBScaleFilter filter, bool threaded)
 {
   BLI_assert_msg(newx > 0 && newy > 0, "Images must be at least 1 on both dimensions!");
   if (ibuf == nullptr) {
diff --git a/source/blender/imbuf/tests/performance/IMB_scaling_performance_test.cc b/source/blender/imbuf/tests/performance/IMB_scaling_performance_test.cc
index 8542190db03..850187a3451 100644
--- a/source/blender/imbuf/tests/performance/IMB_scaling_performance_test.cc
+++ b/source/blender/imbuf/tests/performance/IMB_scaling_performance_test.cc
@@ -15,11 +15,11 @@ using namespace blender;
 static constexpr int SRC_X = 5123;
 static constexpr int SRC_Y = 4091;
 
-static constexpr int DST_SMALLER_X = (int)(SRC_X * 0.21f);
-static constexpr int DST_SMALLER_Y = (int)(SRC_Y * 0.67f);
+static constexpr int DST_SMALLER_X = int(SRC_X * 0.21f);
+static constexpr int DST_SMALLER_Y = int(SRC_Y * 0.67f);
 
-static constexpr int DST_LARGER_X = (int)(SRC_X * 1.19f);
-static constexpr int DST_LARGER_Y = (int)(SRC_Y * 2.13f);
+static constexpr int DST_LARGER_X = int(SRC_X * 1.19f);
+static constexpr int DST_LARGER_Y = int(SRC_Y * 2.13f);
 
 static ImBuf *create_src_image(bool use_float)
 {
diff --git a/source/blender/io/grease_pencil/intern/grease_pencil_io.cc b/source/blender/io/grease_pencil/intern/grease_pencil_io.cc
index 6391cb1e7d0..df3e6ccabd2 100644
--- a/source/blender/io/grease_pencil/intern/grease_pencil_io.cc
+++ b/source/blender/io/grease_pencil/intern/grease_pencil_io.cc
@@ -52,7 +52,7 @@ static float get_average(const Span<float> values)
 static ColorGeometry4f get_average(const Span<ColorGeometry4f> values)
 {
   if (values.is_empty()) {
-    return ColorGeometry4f(0);
+    return ColorGeometry4f(nullptr);
   }
   /* ColorGeometry4f does not support arithmetic directly. */
   Span<float4> rgba_values = values.cast<float4>();
diff --git a/source/blender/io/grease_pencil/intern/grease_pencil_io_import_svg.cc b/source/blender/io/grease_pencil/intern/grease_pencil_io_import_svg.cc
index b8c2242f493..a271023e7e1 100644
--- a/source/blender/io/grease_pencil/intern/grease_pencil_io_import_svg.cc
+++ b/source/blender/io/grease_pencil/intern/grease_pencil_io_import_svg.cc
@@ -286,7 +286,7 @@ bool SVGImporter::read(StringRefNull filepath)
   constexpr float svg_dpi = 96.0f;
 
   char abs_filepath[FILE_MAX];
-  BLI_strncpy(abs_filepath, filepath.c_str(), sizeof(abs_filepath));
+  STRNCPY(abs_filepath, filepath.c_str());
   BLI_path_abs(abs_filepath, BKE_main_blendfile_path_from_global());
 
   NSVGimage *svg_data = nullptr;
diff --git a/source/blender/makesdna/intern/dna_genfile.cc b/source/blender/makesdna/intern/dna_genfile.cc
index 537e7e68c58..62b3576442a 100644
--- a/source/blender/makesdna/intern/dna_genfile.cc
+++ b/source/blender/makesdna/intern/dna_genfile.cc
@@ -550,7 +550,7 @@ static bool init_structDNA(SDNA *sdna, bool do_endian_swap, const char **r_error
     const int mat4x4f_struct_index = DNA_struct_find_index_without_alias_ex(
         sdna, "mat4x4f", &dummy_index);
     if (mat4x4f_struct_index > 0) {
-      SDNA_Struct *struct_info = sdna->structs[mat4x4f_struct_index];
+      const SDNA_Struct *struct_info = sdna->structs[mat4x4f_struct_index];
       const int mat4x4f_type_index = struct_info->type_index;
       sdna->types_alignment[mat4x4f_type_index] = alignof(blender::float4x4);
     }
diff --git a/source/blender/sequencer/intern/disk_cache.cc b/source/blender/sequencer/intern/disk_cache.cc
index 61ad8b834e3..c1769066ef0 100644
--- a/source/blender/sequencer/intern/disk_cache.cc
+++ b/source/blender/sequencer/intern/disk_cache.cc
@@ -478,7 +478,9 @@ static size_t seq_disk_cache_write_header(FILE *file, const DiskCacheHeader *hea
   return fwrite(header, sizeof(*header), 1, file);
 }
 
-static int seq_disk_cache_add_header_entry(SeqCacheKey *key, ImBuf *ibuf, DiskCacheHeader *header)
+static int seq_disk_cache_add_header_entry(const SeqCacheKey *key,
+                                           ImBuf *ibuf,
+                                           DiskCacheHeader *header)
 {
   int i;
   uint64_t offset = sizeof(*header);
@@ -528,7 +530,7 @@ static int seq_disk_cache_add_header_entry(SeqCacheKey *key, ImBuf *ibuf, DiskCa
   return i;
 }
 
-static int seq_disk_cache_get_header_entry(SeqCacheKey *key, const DiskCacheHeader *header)
+static int seq_disk_cache_get_header_entry(const SeqCacheKey *key, const DiskCacheHeader *header)
 {
   for (int i = 0; i < DCACHE_IMAGES_PER_FILE; i++) {
     if (header->entry[i].frameno == key->frame_index) {
diff --git a/source/blender/sequencer/intern/effects.cc b/source/blender/sequencer/intern/effects.cc
index 9c830c09223..36558619c88 100644
--- a/source/blender/sequencer/intern/effects.cc
+++ b/source/blender/sequencer/intern/effects.cc
@@ -960,7 +960,7 @@ static void do_blend_effect_float(
 }
 
 static void do_blend_effect_byte(
-    float fac, int x, int y, uchar *rect1, uchar *rect2, int btype, uchar *out)
+    float fac, int x, int y, const uchar *rect1, uchar *rect2, int btype, uchar *out)
 {
   switch (btype) {
     case SEQ_TYPE_ADD:
diff --git a/source/blender/sequencer/intern/strip_retiming.cc b/source/blender/sequencer/intern/strip_retiming.cc
index 0ad00e20253..6ce77fb31e0 100644
--- a/source/blender/sequencer/intern/strip_retiming.cc
+++ b/source/blender/sequencer/intern/strip_retiming.cc
@@ -415,7 +415,7 @@ void SEQ_retiming_remove_multiple_keys(Sequence *seq,
   }
 
   /* Sanitize keys to be removed. */
-  keys_to_remove.remove_if([&](SeqRetimingKey *key) {
+  keys_to_remove.remove_if([&](const SeqRetimingKey *key) {
     return key->strip_frame_index == 0 || SEQ_retiming_is_last_key(seq, key) ||
            SEQ_retiming_key_is_transition_type(key);
   });