Michael137 wrote: > How do we explain that for my global variable `class`, > > (lldb) expr class = 110 > > works when I happen to be stopped in a C frame, but if I can't find a C frame > around there's no way I can replicate that behavior?
> How do we explain that for my global variable `class`, > > > > (lldb) expr class = 110 > > > > works when I happen to be stopped in a C frame, but if I can't find a C frame > around there's no way I can replicate that behavior? Good question. The reason it works for your example when stopped in a C frame is that the Clang expression evaluator has a workaround in it to allow C++ keywords in pure C/ObjC expressions. If the frame (or before this patch the `--language` flag was C/ObjC), we explicitly "unmark" the reserved C++ keywords here: https://github.com/llvm/llvm-project/blob/cc365331af423de99ae98655d035e4892842fe97/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp#L848-L861 But that in itself still has a workaround to make C-expressions work (because we rely on `using` to capture local variables) ``` static void RemoveCppKeyword(IdentifierTable &idents, llvm::StringRef token) { // FIXME: 'using' is used by LLDB for local variables, so we can't remove // this keyword without breaking this functionality. if (token == "using") return; ``` But we're still lying to the user about this being pure C expression evaluation. All-in-all, in my opinion, it would be best to keep this workaround contained to just expression evaluation from C/ObjC-frames. If we're stopped in a context where these identifiers were used as variable names, presumably that frame must be a language where this was allowed in. So we would still support the majority of use-cases. The only scenario I can think of that this breaks is that if we're stopped in a C-frame, then declare a top-level variable in the expression context with a reserved identifier in the name, and then switch to a C++ frame and try to use it: ``` frame #3: 0x000000010000046c a.out`func at lib.c:2:14 1 #include <stdlib.h> -> 2 int func() { abort(); } (lldb) expr --top-level -- int namespace = 10; (lldb) expr namespace (int) $0 = 10 (lldb) up frame #4: 0x0000000100000454 a.out`main at main.cpp:6:5 1 extern "C" { 2 int func(); 3 } 4 5 int main() { -> 6 func(); 7 } (lldb) expr namespace ˄ ╰─ error: expected identifier or '{' (lldb) down ``` Is that a scenario we want to support? https://github.com/llvm/llvm-project/pull/156648 _______________________________________________ lldb-commits mailing list lldb-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits
