https://github.com/Michael137 updated
https://github.com/llvm/llvm-project/pull/135944
>From 28ffd29ac558c8eb3ec8b3305480f237c822b4fd Mon Sep 17 00:00:00 2001
From: Michael Buch <michaelbuc...@gmail.com>
Date: Wed, 16 Apr 2025 11:46:29 +0200
Subject: [PATCH 1/2] [lldb][DataFormatter] Surface CalculateNumChildren errors
in std::vector summary
When the data-formatters happen to break (e.g., due to layout changes in
libc++), there's no clear indicator of them failing from a user's perspective.
We just show:
```
(std::vector<int>) v = size=0 {}
```
which is highly misleading, especially if `v.size()` returns a non-zero size.
This patch surfaces the various errors that could occur when calculating the
number of children of a vector.
---
.../Language/CPlusPlus/LibCxxVector.cpp | 21 ++++++++---
lldb/source/ValueObject/ValueObject.cpp | 12 +++++--
.../libcxx-simulators/invalid-vector/Makefile | 3 ++
...taFormatterLibcxxInvalidVectorSimulator.py | 35 +++++++++++++++++++
.../libcxx-simulators/invalid-vector/main.cpp | 26 ++++++++++++++
5 files changed, 89 insertions(+), 8 deletions(-)
create mode 100644
lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx-simulators/invalid-vector/Makefile
create mode 100644
lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx-simulators/invalid-vector/TestDataFormatterLibcxxInvalidVectorSimulator.py
create mode 100644
lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx-simulators/invalid-vector/main.cpp
diff --git a/lldb/source/Plugins/Language/CPlusPlus/LibCxxVector.cpp
b/lldb/source/Plugins/Language/CPlusPlus/LibCxxVector.cpp
index d538cac9f9134..ce2261b6f03c3 100644
--- a/lldb/source/Plugins/Language/CPlusPlus/LibCxxVector.cpp
+++ b/lldb/source/Plugins/Language/CPlusPlus/LibCxxVector.cpp
@@ -83,19 +83,30 @@ lldb_private::formatters::LibcxxStdVectorSyntheticFrontEnd::
llvm::Expected<uint32_t> lldb_private::formatters::
LibcxxStdVectorSyntheticFrontEnd::CalculateNumChildren() {
if (!m_start || !m_finish)
- return 0;
+ return llvm::createStringError(
+ "Failed to determine start/end of vector data.");
+
uint64_t start_val = m_start->GetValueAsUnsigned(0);
uint64_t finish_val = m_finish->GetValueAsUnsigned(0);
- if (start_val == 0 || finish_val == 0)
+ // A default-initialized empty vector.
+ if (start_val == 0 && finish_val == 0)
return 0;
- if (start_val >= finish_val)
- return 0;
+ if (start_val == 0)
+ return llvm::createStringError("Invalid value for start of vector.");
+
+ if (finish_val == 0)
+ return llvm::createStringError("Invalid value for end of vector.");
+
+ if (start_val > finish_val)
+ return llvm::createStringError(
+ "Start of vector data begins after end pointer.");
size_t num_children = (finish_val - start_val);
if (num_children % m_element_size)
- return 0;
+ return llvm::createStringError("Size not multiple of element size.");
+
return num_children / m_element_size;
}
diff --git a/lldb/source/ValueObject/ValueObject.cpp
b/lldb/source/ValueObject/ValueObject.cpp
index eac24353de90b..8741cb7343166 100644
--- a/lldb/source/ValueObject/ValueObject.cpp
+++ b/lldb/source/ValueObject/ValueObject.cpp
@@ -1521,10 +1521,16 @@ bool ValueObject::DumpPrintableRepresentation(
str = GetLocationAsCString();
break;
- case eValueObjectRepresentationStyleChildrenCount:
- strm.Printf("%" PRIu64 "", (uint64_t)GetNumChildrenIgnoringErrors());
- str = strm.GetString();
+ case eValueObjectRepresentationStyleChildrenCount: {
+ if (auto err = GetNumChildren()) {
+ strm.Printf("%" PRIu32, *err);
+ str = strm.GetString();
+ } else {
+ strm << "error: " << toString(err.takeError());
+ str = strm.GetString();
+ }
break;
+ }
case eValueObjectRepresentationStyleType:
str = GetTypeName().GetStringRef();
diff --git
a/lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx-simulators/invalid-vector/Makefile
b/lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx-simulators/invalid-vector/Makefile
new file mode 100644
index 0000000000000..38cfa81053488
--- /dev/null
+++
b/lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx-simulators/invalid-vector/Makefile
@@ -0,0 +1,3 @@
+CXX_SOURCES := main.cpp
+override CXXFLAGS_EXTRAS += -std=c++14
+include Makefile.rules
diff --git
a/lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx-simulators/invalid-vector/TestDataFormatterLibcxxInvalidVectorSimulator.py
b/lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx-simulators/invalid-vector/TestDataFormatterLibcxxInvalidVectorSimulator.py
new file mode 100644
index 0000000000000..6986d71c37a8b
--- /dev/null
+++
b/lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx-simulators/invalid-vector/TestDataFormatterLibcxxInvalidVectorSimulator.py
@@ -0,0 +1,35 @@
+"""
+Test we can understand various layouts of the libc++'s std::string
+"""
+
+
+import lldb
+from lldbsuite.test.decorators import *
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test import lldbutil
+import functools
+
+
+class LibcxxInvalidVectorDataFormatterSimulatorTestCase(TestBase):
+ NO_DEBUG_INFO_TESTCASE = True
+
+ def test(self):
+ self.build()
+ lldbutil.run_to_source_breakpoint(self, "return 0",
lldb.SBFileSpec("main.cpp"))
+
+ self.expect(
+ "frame variable v1",
+ substrs=["size=error: Invalid value for end of vector."],
+ )
+ self.expect(
+ "frame variable v2",
+ substrs=["size=error: Invalid value for start of vector."],
+ )
+ self.expect(
+ "frame variable v3",
+ substrs=["size=error: Start of vector data begins after end
pointer."],
+ )
+ self.expect(
+ "frame variable v4",
+ substrs=["size=error: Failed to determine start/end of vector
data."],
+ )
diff --git
a/lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx-simulators/invalid-vector/main.cpp
b/lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx-simulators/invalid-vector/main.cpp
new file mode 100644
index 0000000000000..c1b9b6724787b
--- /dev/null
+++
b/lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx-simulators/invalid-vector/main.cpp
@@ -0,0 +1,26 @@
+#define COMPRESSED_PAIR_REV 2
+#include <libcxx-simulators-common/compressed_pair.h>
+
+namespace std {
+namespace __1 {
+template <typename T> struct vector {
+ T *__begin_;
+ T *__end_;
+ _LLDB_COMPRESSED_PAIR(T *, __cap_ = nullptr, void *, __alloc_);
+};
+} // namespace __1
+
+namespace __2 {
+template <typename T> struct vector {};
+} // namespace __2
+} // namespace std
+
+int main() {
+ int arr[] = {1, 2, 3};
+ std::__1::vector<int> v1{.__begin_ = arr, .__end_ = nullptr};
+ std::__1::vector<int> v2{.__begin_ = nullptr, .__end_ = arr};
+ std::__1::vector<int> v3{.__begin_ = &arr[3], .__end_ = arr};
+ std::__2::vector<int> v4;
+
+ return 0;
+}
>From b5b1b76bb0258d22fed1967f96d60f4adfbf9d4a Mon Sep 17 00:00:00 2001
From: Michael Buch <michaelbuc...@gmail.com>
Date: Wed, 16 Apr 2025 13:17:18 +0200
Subject: [PATCH 2/2] fixup! add another test-case
---
...TestDataFormatterLibcxxInvalidVectorSimulator.py | 4 ++++
.../libcxx-simulators/invalid-vector/main.cpp | 13 ++++++++++++-
2 files changed, 16 insertions(+), 1 deletion(-)
diff --git
a/lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx-simulators/invalid-vector/TestDataFormatterLibcxxInvalidVectorSimulator.py
b/lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx-simulators/invalid-vector/TestDataFormatterLibcxxInvalidVectorSimulator.py
index 6986d71c37a8b..8788ea7be882d 100644
---
a/lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx-simulators/invalid-vector/TestDataFormatterLibcxxInvalidVectorSimulator.py
+++
b/lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx-simulators/invalid-vector/TestDataFormatterLibcxxInvalidVectorSimulator.py
@@ -33,3 +33,7 @@ def test(self):
"frame variable v4",
substrs=["size=error: Failed to determine start/end of vector
data."],
)
+ self.expect(
+ "frame variable v5",
+ substrs=["size=error: Size not multiple of element size."],
+ )
diff --git
a/lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx-simulators/invalid-vector/main.cpp
b/lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx-simulators/invalid-vector/main.cpp
index c1b9b6724787b..b8f0eccf0057b 100644
---
a/lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx-simulators/invalid-vector/main.cpp
+++
b/lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx-simulators/invalid-vector/main.cpp
@@ -13,14 +13,25 @@ template <typename T> struct vector {
namespace __2 {
template <typename T> struct vector {};
} // namespace __2
+
+namespace __3 {
+template <typename T> struct vector {
+ T *__begin_;
+ T *__end_;
+ _LLDB_COMPRESSED_PAIR(short *, __cap_ = nullptr, void *, __alloc_);
+};
+} // namespace __3
} // namespace std
int main() {
int arr[] = {1, 2, 3};
std::__1::vector<int> v1{.__begin_ = arr, .__end_ = nullptr};
std::__1::vector<int> v2{.__begin_ = nullptr, .__end_ = arr};
- std::__1::vector<int> v3{.__begin_ = &arr[3], .__end_ = arr};
+ std::__1::vector<int> v3{.__begin_ = &arr[2], .__end_ = arr};
std::__2::vector<int> v4;
+ char carr[] = {'a'};
+ std::__3::vector<char> v5{.__begin_=carr, .__end_=carr + 1};
+
return 0;
}
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