[vcpkg] Improve Json error messages (#12981)

* [vcpkg] Fix error reporting on json parse failure

* [vcpkg] Track manifest path for use in diagnostics

* [vcpkg] Use by-value for consumer API. Improve trailing comma diagnostic.

* [vcpkg] Track errors directly inside Json::Reader

* [vcpkg] Fixup use of .u8string()

Co-authored-by: Robert Schumacher <roschuma@microsoft.com>

1 files changed, 13 insertions, 2 deletions

diff --git a/toolsrc/src/vcpkg-test/json.cpp b/toolsrc/src/vcpkg-test/json.cpp
index 0b9941861..6858a5ac8 100644
--- a/toolsrc/src/vcpkg-test/json.cpp
+++ b/toolsrc/src/vcpkg-test/json.cpp
@@ -28,8 +28,8 @@ static std::string mystringify(const Value& val) { return Json::stringify(val, J
 
 TEST_CASE ("JSON stringify weird strings", "[json]")
 {
-    vcpkg::StringView str = U8_STR("😀 😁 😂 🤣 😃 😄 😅 😆 😉");
-    REQUIRE(mystringify(Value::string(str)) == ('"' + str.to_string() + "\"\n"));
+    std::string str = U8_STR("😀 😁 😂 🤣 😃 😄 😅 😆 😉");
+    REQUIRE(mystringify(Value::string(str)) == ('"' + str + "\"\n"));
     REQUIRE(mystringify(Value::string("\xED\xA0\x80")) == "\"\\ud800\"\n"); // unpaired surrogate
 }
 
@@ -228,3 +228,14 @@ TEST_CASE ("JSON parse full file", "[json]")
     }
     REQUIRE(res);
 }
+
+TEST_CASE ("JSON track newlines", "[json]")
+{
+    auto res = Json::parse("{\n,", fs::u8path("filename"));
+    REQUIRE(!res);
+    REQUIRE(res.error()->format() ==
+            R"(Error: filename:2:1: Unexpected character; expected property name
+   on expression: ,
+                  ^
+)");
+}