[Lldb-commits] [lldb] [lldb] Fix assertion caused by invalid SupportFileSP (PR #162710)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-lldb

Author: Jonas Devlieghere (JDevlieghere)

<details>
<summary>Changes</summary>

SupportFileSP should never be null, and instead should use a default constructed SupportFile to represent an invalid instance. This is because the class used to be a value type before it became polymorphic.

We have various places in LLDB where we check this precondition, including in DisplaySourceLinesWithLineNumbers. The assertion was tripped when calling GetStartLineSourceInfo which starts by resetting the SupportFileSP and has a series of early returns which leave the shared pointer in that state.

rdar://161607247

---
Full diff: https://github.com/llvm/llvm-project/pull/162710.diff


1 Files Affected:

- (modified) lldb/source/Symbol/Function.cpp (+1-1) 


``````````diff
diff --git a/lldb/source/Symbol/Function.cpp b/lldb/source/Symbol/Function.cpp
index 6114eccd935ee..2be1e389aa1d0 100644
--- a/lldb/source/Symbol/Function.cpp
+++ b/lldb/source/Symbol/Function.cpp
@@ -275,7 +275,7 @@ Function::~Function() = default;
 void Function::GetStartLineSourceInfo(SupportFileSP &source_file_sp,
                                       uint32_t &line_no) {
   line_no = 0;
-  source_file_sp.reset();
+  source_file_sp = std::make_shared<SupportFile>();
 
   if (m_comp_unit == nullptr)
     return;

``````````

</details>


https://github.com/llvm/llvm-project/pull/162710