[llvm] 6da200f - Fix llvm::StripTemplateParameters to not return an empty name. (#157553)

[via llvm-commits]

Author: Greg Clayton
Date: 2025-12-16T09:20:56-08:00
New Revision: 6da200f72c5af1ae572bbf77f11ee8471a8c8199

URL: https://github.com/llvm/llvm-project/commit/6da200f72c5af1ae572bbf77f11ee8471a8c8199
DIFF: https://github.com/llvm/llvm-project/commit/6da200f72c5af1ae572bbf77f11ee8471a8c8199.diff

LOG: Fix llvm::StripTemplateParameters to not return an empty name. (#157553)

llvm::StripTemplateParameters was used to add accelerator table entries
to the DWARF accelerator tables by adding and entry for the template
name without the template. There is a bug where if a string starts with
a '<' character, this function would return an std::optional<StringRef>
that was empty. This causes invalid entries to be added to __apple_XXXX
accelerator tables where entries with empty strings would be added and
were causing issues with the AppleAcceleratorTable::Iterator before the
fix that was submitted
(https://github.com/llvm/llvm-project/pull/157538).

Added: 
    

Modified: 
    llvm/lib/DebugInfo/DWARF/DWARFAcceleratorTable.cpp
    llvm/unittests/DebugInfo/DWARF/DWARFAcceleratorTableTest.cpp

Removed: 
    


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diff  --git a/llvm/lib/DebugInfo/DWARF/DWARFAcceleratorTable.cpp b/llvm/lib/DebugInfo/DWARF/DWARFAcceleratorTable.cpp
index cf5b7fb650b43..e442b5182f6a4 100644
--- a/llvm/lib/DebugInfo/DWARF/DWARFAcceleratorTable.cpp
+++ b/llvm/lib/DebugInfo/DWARF/DWARFAcceleratorTable.cpp
@@ -1150,5 +1150,8 @@ std::optional<StringRef> llvm::StripTemplateParameters(StringRef Name) {
   while (NumLeftAnglesToSkip--)
     StartOfTemplate = Name.find('<', StartOfTemplate) + 1;
 
-  return Name.substr(0, StartOfTemplate - 1);
+  StringRef Result = Name.substr(0, StartOfTemplate - 1);
+  if (Result.empty())
+    return std::nullopt;
+  return Result;
 }

diff  --git a/llvm/unittests/DebugInfo/DWARF/DWARFAcceleratorTableTest.cpp b/llvm/unittests/DebugInfo/DWARF/DWARFAcceleratorTableTest.cpp
index dedcf816cf63f..82cc02c921d15 100644
--- a/llvm/unittests/DebugInfo/DWARF/DWARFAcceleratorTableTest.cpp
+++ b/llvm/unittests/DebugInfo/DWARF/DWARFAcceleratorTableTest.cpp
@@ -299,4 +299,18 @@ TEST(DWARFDebugNames, UnsupportedForm) {
       Sections,
       FailedWithMessage("unsupported Form for YAML debug_names emitter"));
 }
+
+TEST(DWARFDebugNames, TestStripTemplateParameters) {
+
+  std::optional<StringRef> stripped_name;
+  // Make sure we can extract the name "foo" from the template parameters.
+  stripped_name = StripTemplateParameters("foo<int>");
+  ASSERT_TRUE(stripped_name.has_value());
+  ASSERT_EQ(*stripped_name, StringRef("foo"));
+  // Make sure that we don't get a valid name back when the string starts with
+  // '<'.
+  stripped_name = StripTemplateParameters("<int>");
+  ASSERT_FALSE(stripped_name.has_value());
+}
+
 } // end anonymous namespace