[clang] 7072b13 - [clang][deps] Call getMemBuffer with RequiresNullTerminator false (#195072)

[via cfe-commits]

Author: Peter Smith
Date: 2026-04-30T17:54:57+01:00
New Revision: 7072b1335103b6dbc4a577956f8a9f0fd4b43b4b

URL: https://github.com/llvm/llvm-project/commit/7072b1335103b6dbc4a577956f8a9f0fd4b43b4b
DIFF: https://github.com/llvm/llvm-project/commit/7072b1335103b6dbc4a577956f8a9f0fd4b43b4b.diff

LOG: [clang][deps] Call getMemBuffer with RequiresNullTerminator false (#195072)

The getMemBuffer() has a default parameter RequiresNullTerminator which
is set to true.

In ModuleCache the MemoryBuffer::getOpenFile is called with /*
RequiresNullTerminator=*/false. This means that initial contents of the
MemoryBuffer may not have a trailing 0x0 at the end of the file.

When assertions are enabled and RequiresNullTerminator is true the
MemoryBuffer will trigger a "Buffer is not null terminated!" assertion
failure if BufEnd[0] != 0.

We have at one build with assertions enabled that is triggering this
MemoryBuffer assertion failure in the check-clang tests:
* ClangScanDeps/modules-dep-args.c
* Driver/modules-driver-import-std.cpp

The failure is specific to one particular machine, we have not been able
to reproduce locally. It is possible that the failure is filesystem type
or path length dependent.

Changing the RequiresNullTerminator in getMemBuffer to false to match
the value of RequiresNullTerminator in getOpenFile fixes the problem and
all tests pass.

Added: 
    

Modified: 
    clang/lib/DependencyScanning/InProcessModuleCache.cpp

Removed: 
    


################################################################################
diff  --git a/clang/lib/DependencyScanning/InProcessModuleCache.cpp b/clang/lib/DependencyScanning/InProcessModuleCache.cpp
index 7bbad3ca1da3a..538ff2952c4f5 100644
--- a/clang/lib/DependencyScanning/InProcessModuleCache.cpp
+++ b/clang/lib/DependencyScanning/InProcessModuleCache.cpp
@@ -179,7 +179,8 @@ class InProcessModuleCache : public ModuleCache {
     }
     Size = Entry.Buffer->getBufferSize();
     ModTime = Entry.ModTime;
-    return llvm::MemoryBuffer::getMemBuffer(*Entry.Buffer);
+    return llvm::MemoryBuffer::getMemBuffer(*Entry.Buffer,
+                                            /* RequiresNullTerminator */ false);
   }
 };
 } // namespace