Fix VLA support in JsonDocument::set()

Author: bblanchon

CHANGELOG.md

@@ -5,6 +5,7 @@ HEAD
 ----
 
 * Forbid `deserializeJson(JsonArray|JsonObject, ...)` (issue #2135)
+* Fix VLA support in `JsonDocument::set()`
 
 v7.2.0 (2024-09-18)
 ------

extras/tests/JsonDocument/CMakeLists.txt

@@ -16,6 +16,7 @@ add_executable(JsonDocumentTests
 	nesting.cpp
 	overflowed.cpp
 	remove.cpp
+	set.cpp
 	shrinkToFit.cpp
 	size.cpp
 	subscript.cpp

extras/tests/JsonDocument/set.cpp

@@ -0,0 +1,79 @@
+#define ARDUINOJSON_ENABLE_ARDUINO_STRING 1
+#define ARDUINOJSON_ENABLE_PROGMEM 1
+#include <ArduinoJson.h>
+
+#include <catch.hpp>
+
+#include "Allocators.hpp"
+#include "Literals.hpp"
+
+TEST_CASE("JsonDocument::set()") {
+  SpyingAllocator spy;
+  JsonDocument doc(&spy);
+
+  SECTION("integer") {
+    doc.set(42);
+
+    REQUIRE(doc.as<std::string>() == "42");
+    REQUIRE(spy.log() == AllocatorLog{});
+  }
+
+  SECTION("const char*") {
+    doc.set("example");
+
+    REQUIRE(doc.as<const char*>() == "example"_s);
+    REQUIRE(spy.log() == AllocatorLog{});
+  }
+
+  SECTION("std::string") {
+    doc.set("example"_s);
+
+    REQUIRE(doc.as<const char*>() == "example"_s);
+    REQUIRE(spy.log() == AllocatorLog{
+                             Allocate(sizeofString("example")),
+                         });
+  }
+
+  SECTION("char*") {
+    char value[] = "example";
+    doc.set(value);
+
+    REQUIRE(doc.as<const char*>() == "example"_s);
+    REQUIRE(spy.log() == AllocatorLog{
+                             Allocate(sizeofString("example")),
+                         });
+  }
+
+  SECTION("Arduino String") {
+    doc.set(String("example"));
+
+    REQUIRE(doc.as<const char*>() == "example"_s);
+    REQUIRE(spy.log() == AllocatorLog{
+                             Allocate(sizeofString("example")),
+                         });
+  }
+
+  SECTION("Flash string") {
+    doc.set(F("example"));
+
+    REQUIRE(doc.as<const char*>() == "example"_s);
+    REQUIRE(spy.log() == AllocatorLog{
+                             Allocate(sizeofString("example")),
+                         });
+  }
+
+#ifdef HAS_VARIABLE_LENGTH_ARRAY
+  SECTION("VLA") {
+    size_t i = 16;
+    char vla[i];
+    strcpy(vla, "example");
+
+    doc.set(vla);
+
+    REQUIRE(doc.as<const char*>() == "example"_s);
+    REQUIRE(spy.log() == AllocatorLog{
+                             Allocate(sizeofString("example")),
+                         });
+  }
+#endif
+}

src/ArduinoJson/Document/JsonDocument.hpp

@@ -142,6 +142,13 @@ class JsonDocument : public detail::VariantOperators<const JsonDocument&> {
     return to<JsonVariant>().set(src);
   }
 
+  // Replaces the root with the specified value.
+  // https://arduinojson.org/v7/api/jsondocument/set/
+  template <typename TChar>
+  bool set(TChar* src) {
+    return to<JsonVariant>().set(src);
+  }
+
   // Clears the document and converts it to the specified type.
   // https://arduinojson.org/v7/api/jsondocument/to/
   template <typename T>