Commit `cdb40936bd`

Andrew Kelley <andrew@ziglang.org>

2022-09-13 12:03:34

properly annotate nullability of ZigLLVMCreateDebugForwardDeclType

This bug manifested as a segfault in stage1 when calling this function. The C++ code looks like this: ```c++ entry->llvm_di_type = ZigLLVMCreateDebugForwardDeclType(g->dbuilder, ZigLLVMTag_DW_structure_type(), full_name, import ? ZigLLVMFileToScope(import->data.structure.root_struct->di_file) : nullptr, import ? import->data.structure.root_struct->di_file : nullptr, line); ``` There is actually no problem here - what happened is that because cross-language LTO was enabled between zig and c++ code, and because Zig annotated the file parameter (3rd line) as being non-null, the C++ code assumed that parameter could not be null, and eagerly dereferenced `import->...`, causing a segfault, since it was null. I verified that this commit fixed the problem and I also verified this hypothesis by disabling LTO and noticing that it indeed avoided the problem.

master

1 parent d31be31

Changed files (1)

src

codegen

llvm

bindings.zig

@@ -1734,8 +1734,8 @@ pub const DIBuilder = opaque {
         dib: *DIBuilder,
         tag: c_uint,
         name: [*:0]const u8,
-        scope: *DIScope,
-        file: *DIFile,
+        scope: ?*DIScope,
+        file: ?*DIFile,
         line: c_uint,
     ) *DIType;

Commit cdb40936bd

Commit `cdb40936bd`