[Lldb-commits] [lldb] [LLDB] Fix type formatting empty c-strings (PR #68924)

[via lldb-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-lldb

Author: Walter Erquinigo (walter-erquinigo)

<details>
<summary>Changes</summary>

The type formatter code is effectively considering empty strings as read errors, which is wrong. The fix is very simple. We should rely on the error object and stop checking the size. I also added a test.


---
Full diff: https://github.com/llvm/llvm-project/pull/68924.diff


3 Files Affected:

- (modified) lldb/source/DataFormatters/TypeFormat.cpp (+3-3) 
- (modified) lldb/test/API/functionalities/data-formatter/builtin-formats/TestBuiltinFormats.py (+16-1) 
- (modified) lldb/test/API/functionalities/data-formatter/builtin-formats/main.cpp (+2) 


``````````diff
diff --git a/lldb/source/DataFormatters/TypeFormat.cpp b/lldb/source/DataFormatters/TypeFormat.cpp
index 5ee89fc0d5eb319..126240aeca65e43 100644
--- a/lldb/source/DataFormatters/TypeFormat.cpp
+++ b/lldb/source/DataFormatters/TypeFormat.cpp
@@ -81,9 +81,9 @@ bool TypeFormatImpl_Format::FormatObject(ValueObject *valobj,
               WritableDataBufferSP buffer_sp(
                   new DataBufferHeap(max_len + 1, 0));
               Address address(valobj->GetPointerValue());
-              if (target_sp->ReadCStringFromMemory(
-                      address, (char *)buffer_sp->GetBytes(), max_len, error) &&
-                  error.Success())
+              target_sp->ReadCStringFromMemory(
+                  address, (char *)buffer_sp->GetBytes(), max_len, error);
+              if (error.Success())
                 data.SetData(buffer_sp);
             }
           }
diff --git a/lldb/test/API/functionalities/data-formatter/builtin-formats/TestBuiltinFormats.py b/lldb/test/API/functionalities/data-formatter/builtin-formats/TestBuiltinFormats.py
index aa768c158b5b5ff..5c49141c176303d 100644
--- a/lldb/test/API/functionalities/data-formatter/builtin-formats/TestBuiltinFormats.py
+++ b/lldb/test/API/functionalities/data-formatter/builtin-formats/TestBuiltinFormats.py
@@ -3,9 +3,9 @@
 """
 
 import lldb
+from lldbsuite.test import lldbutil
 from lldbsuite.test.decorators import *
 from lldbsuite.test.lldbtest import *
-from lldbsuite.test import lldbutil
 
 
 class TestCase(TestBase):
@@ -19,6 +19,21 @@ def getFormatted(self, format, expr):
         self.assertTrue(result.Succeeded(), result.GetError())
         return result.GetOutput()
 
+    @no_debug_info_test
+    @skipIfWindows
+    def testAllPlatforms(self):
+        self.build()
+        lldbutil.run_to_source_breakpoint(
+            self, "// break here", lldb.SBFileSpec("main.cpp")
+        )
+        # We can dump correctly non char* c-strings with explicit formatting.
+        self.assertIn(' = ""', self.getFormatted("c-string", "void_empty_cstring"));
+        self.assertIn(' = ""', self.getFormatted("c-string", "empty_cstring"));
+
+
+    # TODO: Move as many asserts as possible within this function to `testAllPlatforms`.
+    # Currently `arm` is being skipped even though many asserts would effectively
+    # pass.
     @no_debug_info_test
     @skipIfWindows
     # uint128_t not available on arm.
diff --git a/lldb/test/API/functionalities/data-formatter/builtin-formats/main.cpp b/lldb/test/API/functionalities/data-formatter/builtin-formats/main.cpp
index 58b8116dfa1ec9b..573c111306c14de 100644
--- a/lldb/test/API/functionalities/data-formatter/builtin-formats/main.cpp
+++ b/lldb/test/API/functionalities/data-formatter/builtin-formats/main.cpp
@@ -1,8 +1,10 @@
 #include <cstdint>
 
 const char cstring[15] = " \033\a\b\f\n\r\t\vaA09\0";
+const char *empty_cstring = "";
 
 int main() {
   int use = *cstring;
+  void *void_empty_cstring = (void *)empty_cstring;
   return use; // break here
 }

``````````

</details>


https://github.com/llvm/llvm-project/pull/68924