[Lldb-commits] [lldb] [lldb] Adjust default target.max-children-depth (PR #149282)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-lldb

Author: Michael Buch (Michael137)

<details>
<summary>Changes</summary>

Deeply nested structs can be noisy, so Apple's LLDB fork sets the default to `4`: https://github.com/swiftlang/llvm-project/blob/9c93adbb283005ab416fd155b75fd43e6a8288ca/lldb/source/Target/TargetProperties.td#L134-L136

Thought it would be useful to upstream this. Though happy to pick a different default or keep it as-is.

---
Full diff: https://github.com/llvm/llvm-project/pull/149282.diff


2 Files Affected:

- (modified) lldb/source/Target/TargetProperties.td (+1-1) 
- (added) lldb/test/Shell/Settings/TestChildDepthTruncation.test (+84) 


``````````diff
diff --git a/lldb/source/Target/TargetProperties.td b/lldb/source/Target/TargetProperties.td
index 656503bb8d228..e6cd48a9d3dad 100644
--- a/lldb/source/Target/TargetProperties.td
+++ b/lldb/source/Target/TargetProperties.td
@@ -99,7 +99,7 @@ let Definition = "target" in {
     DefaultUnsignedValue<24>,
     Desc<"Maximum number of children to expand in any level of depth.">;
   def MaxChildrenDepth: Property<"max-children-depth", "UInt64">,
-    DefaultUnsignedValue<0xFFFFFFFF>,
+    DefaultUnsignedValue<4>,
     Desc<"Maximum depth to expand children.">;
   def MaxSummaryLength: Property<"max-string-summary-length", "UInt64">,
     DefaultUnsignedValue<1024>,
diff --git a/lldb/test/Shell/Settings/TestChildDepthTruncation.test b/lldb/test/Shell/Settings/TestChildDepthTruncation.test
new file mode 100644
index 0000000000000..e0e6cda516655
--- /dev/null
+++ b/lldb/test/Shell/Settings/TestChildDepthTruncation.test
@@ -0,0 +1,84 @@
+# Test that we warn the user about truncated output
+# when target.max-children-depth wasn't explicitly set.
+
+# RUN: split-file %s %t
+# RUN: %clang_host -g -gdwarf %t/main.cpp -o %t.out
+# RUN: %lldb -x -b -s %t/dwim-commands.input %t.out -o exit 2>&1 \
+# RUN:       | FileCheck %s --check-prefix=DWIM
+#
+# RUN: %lldb -x -b -s %t/expr-commands.input %t.out -o exit 2>&1 \
+# RUN:       | FileCheck %s --check-prefix=EXPR
+#
+# RUN: %lldb -x -b -s %t/frame-var-commands.input %t.out -o exit 2>&1 \
+# RUN:       | FileCheck %s --check-prefix=VAR
+#
+# RUN: %lldb -x -b -s %t/with-setting-commands.input %t.out -o exit 2>&1 \
+# RUN:       | FileCheck %s --check-prefix=SETTING
+
+#--- main.cpp
+
+struct L1 {
+    int w;
+    struct L2 {
+        int x;
+        struct L3 {
+            int y;
+            struct L4 {
+              int z;
+                struct L5 {
+                  int a;
+                } l5;
+            } l4;
+        } l3;
+    } l2;
+};
+
+int main() {
+  L1 nested;
+  __builtin_debugtrap();
+}
+
+#--- dwim-commands.input
+
+run
+dwim-print nested
+frame variable nested
+
+DWIM:      (lldb) dwim-print nested
+DWIM:      *** Some of the displayed variables have a greater depth of members
+DWIM-SAME: use the --depth option to dwim-print
+DWIM:      (lldb) frame variable nested
+DWIM-NOT:  *** Some of the displayed variables have a greater depth of members
+
+#--- expr-commands.input
+
+run
+expression nested
+frame variable nested
+
+EXPR:      (lldb) expression nested
+EXPR:      *** Some of the displayed variables have a greater depth of members
+EXPR-SAME: use the --depth option to expression
+EXPR:      (lldb) frame variable nested
+EXPR-NOT:  *** Some of the displayed variables have a greater depth of members
+
+#--- frame-var-commands.input
+
+run
+frame variable nested
+frame variable nested
+
+VAR:      (lldb) frame variable nested
+VAR:      *** Some of the displayed variables have a greater depth of members
+VAR-SAME: use the --depth option to frame variable
+VAR:      (lldb) frame variable nested
+VAR-NOT:  *** Some of the displayed variables have a greater depth of members
+
+#--- with-setting-commands.input
+
+run
+settings set target.max-children-depth 1
+frame variable nested
+
+SETTING:      (lldb) frame variable nested
+SETTING-NOT:  *** Some of the displayed variables have a greater depth of members

``````````

</details>


https://github.com/llvm/llvm-project/pull/149282