[lldb] Adjust default target.max-children-depth #149282
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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.
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@llvm/pr-subscribers-lldb Author: Michael Buch (Michael137) ChangesDeeply nested structs can be noisy, so Apple's LLDB fork sets the default to 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:
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
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JDevlieghere
approved these changes
Jul 17, 2025
DavidSpickett
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Jul 18, 2025
#149282 changed the max children depth and that caused one part of the output to become `{...}`. The original PR set a higher limit for a different test, so I'm doing the same here.
llvm-sync bot
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Jul 18, 2025
llvm/llvm-project#149282 changed the max children depth and that caused one part of the output to become `{...}`. The original PR set a higher limit for a different test, so I'm doing the same here.
Michael137
added a commit
that referenced
this pull request
Jul 18, 2025
Fixes failure after we introduced a default limit in #149282 We already did this test change on the Apple fork.
llvm-sync bot
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Jul 18, 2025
…h in test Fixes failure after we introduced a default limit in llvm/llvm-project#149282 We already did this test change on the Apple fork.
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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-L136Thought it would be useful to upstream this. Though happy to pick a different default or keep it as-is.