[lldb] Provide a better error message for missing symbols

[adrian-prantl]

This adds a hint to the missing symbols error message to make it easier to understand what this means to users.

[llvmbot]

@llvm/pr-subscribers-lldb

Author: Adrian Prantl (adrian-prantl)

Changes

This adds a hint to the missing symbols error message to make it easier to understand what this means to users.

---

Full diff: https://github.com/llvm/llvm-project/pull/89433.diff

2 Files Affected:

• (modified) lldb/source/Expression/IRExecutionUnit.cpp (+3-1)
• (modified) lldb/test/API/lang/cpp/constructors/TestCppConstructors.py (+2-1)

diff --git a/lldb/source/Expression/IRExecutionUnit.cpp b/lldb/source/Expression/IRExecutionUnit.cpp
index cb9bee8733e15d..8d4e5aaf9fe7ea 100644
--- a/lldb/source/Expression/IRExecutionUnit.cpp
+++ b/lldb/source/Expression/IRExecutionUnit.cpp
@@ -431,7 +431,9 @@ void IRExecutionUnit::GetRunnableInfo(Status &error, lldb::addr_t &func_addr,
     }
 
     m_failed_lookups.clear();
-
+    ss.PutCString(
+        "\nHint: The expression tried to call a function missing from the "
+        "target, perhaps because it was optimized out by the compiler.");
     error.SetErrorString(ss.GetString());
 
     return;
diff --git a/lldb/test/API/lang/cpp/constructors/TestCppConstructors.py b/lldb/test/API/lang/cpp/constructors/TestCppConstructors.py
index 6724bfc8ed78e0..d73b2af1ca077c 100644
--- a/lldb/test/API/lang/cpp/constructors/TestCppConstructors.py
+++ b/lldb/test/API/lang/cpp/constructors/TestCppConstructors.py
@@ -47,7 +47,8 @@ def test_constructors(self):
         self.expect(
             "expr ClassWithDeletedDefaultCtor().value",
             error=True,
-            substrs=["Couldn't look up symbols:"],
+            substrs=["Couldn't look up symbols:",
+                     "function missing"],
         )
 
     @skipIfWindows  # Can't find operator new.

[github-actions]

✅ With the latest revision this PR passed the Python code formatter.

[felipepiovezan]

This LGTM!
I like the wording in the sense that it uses a slightly less "systemy" language, and so it becomes less cryptic to a wider audience.

[JDevlieghere]

LGMT with the formatting fixed.