Add "struct Xxx has no member named reallocate"

See bblanchon/ArduinoJson#2118

Author: bblanchon

src/pages/v7/compiletime/index.md

@@ -35,6 +35,11 @@ options:
     summary: Error says "`class Xxx` has no member named `read`"
     page: no-member-named-read.md
 
+  class-has-no-member-named-reallocate:
+    label: "`class Xxx` has no member named `reallocate`; did you mean `deallocate`?"
+    summary: Error says "`class Xxx` has no member named `reallocate`"
+    page: no-member-named-reallocate/index.md
+
   pointer-to-object:
     label: '`const void*` is not a pointer-to-object type'
     summary: Error says "`const void*` is not a pointer-to-object type"
@@ -105,6 +110,11 @@ options:
     summary: Error says "`struct Xxx` has no member named `read`"
     page: no-member-named-read.md
 
+  struct-has-no-member-named-reallocate:
+    label: "`struct Xxx` has no member named `reallocate`; did you mean `deallocate`?"
+    summary: Error says "`struct Xxx` has no member named `reallocate`"
+    page: no-member-named-reallocate/index.md
+
   range-based-for-requires-begin:
     label: this range-based `for` statement requires a suitable "begin" function and none was found
     summary: Error says "this range-based `for` statement requires a suitable "begin" function and none was found"

src/pages/v7/compiletime/no-member-named-reallocate/index.md

@@ -0,0 +1,22 @@
+---
+options:
+  upgrade:
+    label: Upgrade to ArduinoJson 7 syntax (recommended)
+    summary: User wants to upgrade to ArduinoJson 7 syntax
+    page: upgrade.md
+  failure:
+    label: Keep to ArduinoJson 6 syntax (quick fix)
+    summary: User wants to keep to ArduinoJson 6 syntax
+    page: keep.md
+---
+
+This error occurs when the following condition are met:
+
+1. The program was designed for ArduinoJson 6.
+2. The program uses a custom allocator.
+3. The custom allocator doesn't define `reallocate()`.
+
+Indeed, in ArduinoJson 6, the `reallocate()` method was optional for custom allocators.  
+It's now mandatory in ArduinoJson 7, and that's why you get this error.
+
+There are two ways to fix this issue. You can either:

src/pages/v7/compiletime/no-member-named-reallocate/keep.md

@@ -0,0 +1,31 @@
+---
+options:
+  success:
+    label: "Yes"
+    summary: Adding the `reallocate()` method fixes the issue
+    page: /done.md
+  failure:
+    label: "No"
+    summary: Adding the `reallocate()` method doesn't fix the issue
+    page: /deadend.md
+---
+
+You must add the `reallocate()` method like so:
+
+```diff
+  struct SpiRamAllocator {
+   void* allocate(size_t size) {
+     return heap_caps_malloc(size, MALLOC_CAP_SPIRAM);
+   }
+   
+   void deallocate(void* pointer) {
+     heap_caps_free(pointer);
+   }
+
++  void* reallocate(void* ptr, size_t new_size) {
++    return heap_caps_realloc(ptr, new_size, MALLOC_CAP_SPIRAM);
++  }
+  };
+```
+
+Did this solve your issue?

src/pages/v7/compiletime/no-member-named-reallocate/upgrade.md

@@ -0,0 +1,40 @@
+---
+options:
+  success:
+    label: "Yes"
+    summary: Upgrading the syntax and adding the `reallocate()` method fixes the issue
+    page: /done.md
+  failure:
+    label: "No"
+    summary: Upgrading the syntax and adding the `reallocate()` method doesn't fix the issue
+    page: /deadend.md
+---
+
+Here is how to upgrade your code:
+
+```diff
+- struct SpiRamAllocator {
++ struct SpiRamAllocator : ArduinoJson::Allocator {
+   void* allocate(size_t size) {
+     return heap_caps_malloc(size, MALLOC_CAP_SPIRAM);
+   }
+   
+   void deallocate(void* pointer) {
+     heap_caps_free(pointer);
+   }
+
++  void* reallocate(void* ptr, size_t new_size) {
++    return heap_caps_realloc(ptr, new_size, MALLOC_CAP_SPIRAM);
++  }
+  };
+
+- using SpiRamJsonDocument = BasicJsonDocument<SpiRamAllocator>;
++ SpiRamAllocator allocator;
+
+- SpiRamJsonDocument doc;
++ JsonDocument doc(&allocator);
+```
+
+For more information about the changes in ArduinoJson 7, please refer to the [upgrade guide](/v7/how-to/upgrade-from-v6/).
+
+Did this solve your issue?