From bed7e90bae677a646bd1a4eb2e311f60aadc6301 Mon Sep 17 00:00:00 2001
From: Martin Duffy <martin.duffy@kitware.com>
Date: Fri, 14 Mar 2025 13:54:25 -0400
Subject: [PATCH] cmJSONState: Use StructuredErrors when available

When the version of JsonCpp permits it, use StructuredErrors to generate
error messages for parse errors in the same style as other CMake-generated
JSON error messages.

Fixes: #26717
---
 Source/cmJSONState.cxx                          | 17 ++++++++++++++++-
 Tests/RunCMake/CMakePresets/Comment-stderr.txt  |  9 +++++++--
 .../invalid-not-json-ctest-stderr.txt           |  9 +++++++--
 3 files changed, 30 insertions(+), 5 deletions(-)

diff --git a/Source/cmJSONState.cxx b/Source/cmJSONState.cxx
index 6a1b0319cb..4827940911 100644
--- a/Source/cmJSONState.cxx
+++ b/Source/cmJSONState.cxx
@@ -4,10 +4,12 @@
 #include "cmJSONState.h"
 
 #include <iterator>
+#include <memory>
 #include <sstream>
 
 #include <cm3p/json/reader.h>
 #include <cm3p/json/value.h>
+#include <cm3p/json/version.h>
 
 #include "cmsys/FStream.hxx"
 
@@ -35,14 +37,27 @@ cmJSONState::cmJSONState(std::string jsonFile, Json::Value* root)
   }
   fin.seekg(finBegin);
 
-  // Parse the document.
   Json::CharReaderBuilder builder;
   Json::CharReaderBuilder::strictMode(&builder.settings_);
   std::string errMsg;
+
+#if JSONCPP_VERSION_HEXA >= 0x01090600
+  // Has StructuredError
+  std::unique_ptr<Json::CharReader> const reader(builder.newCharReader());
+  reader->parse(doc.data(), doc.data() + doc.size(), root, &errMsg);
+  std::vector<Json::CharReader::StructuredError> structuredErrors =
+    reader->getStructuredErrors();
+  for (auto const& structuredError : structuredErrors) {
+    this->AddErrorAtOffset(structuredError.message,
+                           structuredError.offset_start);
+  }
+#else
+  // No StructuredError Available, Use error string from jsonCpp
   if (!Json::parseFromStream(builder, fin, root, &errMsg)) {
     errMsg = cmStrCat("JSON Parse Error: ", this->Filename, ":\n", errMsg);
     this->AddError(errMsg);
   }
+#endif
 }
 
 void cmJSONState::AddError(std::string const& errMsg)
diff --git a/Tests/RunCMake/CMakePresets/Comment-stderr.txt b/Tests/RunCMake/CMakePresets/Comment-stderr.txt
index 8619cf5fad..9fdb517422 100644
--- a/Tests/RunCMake/CMakePresets/Comment-stderr.txt
+++ b/Tests/RunCMake/CMakePresets/Comment-stderr.txt
@@ -1,8 +1,13 @@
 ^CMake Error: Could not read presets from [^
 ]*/Tests/RunCMake/CMakePresets/Comment:
-JSON Parse Error: [^
+(CMakePresets.json:1: Syntax error: value, object or array expected.
+// Comment
+\^
+CMakePresets.json:2: Extra non-whitespace after JSON value.
+{
+\^|JSON Parse Error: [^
 ]*Comment\/CMakePresets.json:
 \* Line 1, Column 1
   Syntax error: value, object or array expected\.
 \* Line 2, Column 1
-  Extra non-whitespace after JSON value\.$
+  Extra non-whitespace after JSON value\.$)
diff --git a/Tests/RunCMake/CTestResourceAllocation/invalid-not-json-ctest-stderr.txt b/Tests/RunCMake/CTestResourceAllocation/invalid-not-json-ctest-stderr.txt
index c77ca8c494..03dce414e0 100644
--- a/Tests/RunCMake/CTestResourceAllocation/invalid-not-json-ctest-stderr.txt
+++ b/Tests/RunCMake/CTestResourceAllocation/invalid-not-json-ctest-stderr.txt
@@ -1,6 +1,11 @@
 ^Could not read/parse resource spec file [^
 ]*/Tests/RunCMake/CTestResourceAllocation/invalid\.json:
-JSON Parse Error: [^
+(invalid.json:1: Syntax error: value, object or array expected.
+This is not a valid JSON file!
+\^
+invalid.json:1: Extra non-whitespace after JSON value.
+This is not a valid JSON file!
+ \^|JSON Parse Error: [^
 ]*/Tests/RunCMake/CTestResourceAllocation/invalid\.json:
 \* Line 1, Column 1
   Syntax error: value, object or array expected\.
@@ -8,7 +13,7 @@ JSON Parse Error: [^
   Extra non-whitespace after JSON value\.
 |\* Line 1, Column 1
   A valid JSON document must be either an array or an object value\.
-)
+))
 Errors while running CTest
 Output from these tests are in: [^
 ]*/Tests/RunCMake/CTestResourceAllocation/invalid-build/Testing/Temporary/LastTest\.log