[clang-tools-extra] Fix clangd call hierarchy crash (PR #179718)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clangd

Author: None (NeKon69)

<details>
<summary>Changes</summary>

[clangd] Fix clangd crash on invalid parameters in incoming/outgoing calls

Previous code that handled json parsing from incoming/outgoing calls did not account for the fact that input can be malformed (e.g. []). My change fixes that by checking if the `ObjectMapper` is valid before doing anything with it. Also added tests to prevent that from happening again.

Fixes #<!-- -->179109

---
Full diff: https://github.com/llvm/llvm-project/pull/179718.diff


2 Files Affected:

- (modified) clang-tools-extra/clangd/Protocol.cpp (+2-2) 
- (modified) clang-tools-extra/clangd/test/call-hierarchy.test (+13-1) 


``````````diff
diff --git a/clang-tools-extra/clangd/Protocol.cpp b/clang-tools-extra/clangd/Protocol.cpp
index 9926f2dd63de5..a697486d48f9c 100644
--- a/clang-tools-extra/clangd/Protocol.cpp
+++ b/clang-tools-extra/clangd/Protocol.cpp
@@ -1511,7 +1511,7 @@ bool fromJSON(const llvm::json::Value &Params, CallHierarchyItem &I,
 bool fromJSON(const llvm::json::Value &Params,
               CallHierarchyIncomingCallsParams &C, llvm::json::Path P) {
   llvm::json::ObjectMapper O(Params, P);
-  return O.map("item", C.item);
+  return O && O.map("item", C.item);
 }
 
 llvm::json::Value toJSON(const CallHierarchyIncomingCall &C) {
@@ -1521,7 +1521,7 @@ llvm::json::Value toJSON(const CallHierarchyIncomingCall &C) {
 bool fromJSON(const llvm::json::Value &Params,
               CallHierarchyOutgoingCallsParams &C, llvm::json::Path P) {
   llvm::json::ObjectMapper O(Params, P);
-  return O.map("item", C.item);
+  return O && O.map("item", C.item);
 }
 
 llvm::json::Value toJSON(const CallHierarchyOutgoingCall &C) {
diff --git a/clang-tools-extra/clangd/test/call-hierarchy.test b/clang-tools-extra/clangd/test/call-hierarchy.test
index 6548ea0068a8d..f0d57b60421a4 100644
--- a/clang-tools-extra/clangd/test/call-hierarchy.test
+++ b/clang-tools-extra/clangd/test/call-hierarchy.test
@@ -34,6 +34,18 @@
 # CHECK-NEXT:      "uri": "file://{{.*}}/clangd-test/main.cpp"
 # CHECK-NEXT:    }
 ---
-{"jsonrpc":"2.0","id":3,"method":"shutdown"}
+{"jsonrpc":"2.0","id":3,"method":"callHierarchy/incomingCalls","params":[]}
+#      CHECK: "error": {
+# CHECK-NEXT:   "code": -32602,
+# CHECK-NEXT:   "message": "failed to decode callHierarchy/incomingCalls request: expected object"
+# CHECK-NEXT:  }
+---
+{"jsonrpc":"2.0","id":4,"method":"callHierarchy/outgoingCalls","params":4}
+#      CHECK: "error": {
+# CHECK-NEXT:   "code": -32602,
+# CHECK-NEXT:   "message": "failed to decode callHierarchy/outgoingCalls request: expected object"
+# CHECK-NEXT:  }
+---
+{"jsonrpc":"2.0","id":5,"method":"shutdown"}
 ---
 {"jsonrpc":"2.0","method":"exit"}

``````````

</details>


https://github.com/llvm/llvm-project/pull/179718