probinson added inline comments.
================
Comment at: lib/CodeGen/CGDebugInfo.cpp:3263-3264
@@ +3262,4 @@
+ const NamespaceDecl *NSDecl = UD.getNominatedNamespace();
+ if (!NSDecl->isAnonymousNamespace() ||
+ CGM.getTarget().getTriple().isPS4CPU()) {
+ DBuilder.createImportedModule(
----------------
rsmith wrote:
> I think we should do this unconditionally, to better match the source
> language semantics, but I'm curious what David, Eric, and other folks on the
> DWARF side think.
David (in previous discussions and review comments) has said he thinks it is
unnecessary as the debugger already must know so much about C++ to get various
things right, it might as well know that it has to implicitly import the
anonymous namespace contents. One example debugger UI allows the user to type
source-like syntax, and requires the debugger to apply (for example) C++
parameter-type matching rules to distinguish between overloaded functions.
Compared to this, implicit imports are child's play.
I believe Eric agrees with David; I don't remember whether Adrian said anything
in the previous iterations of this patch.
I believe the explicit (although artificial) import is a good thing, because it
matches the source language semantics. I find an important distinction between
"which declarations are available in this scope" and "how does the user
disambiguate declarations in this scope." As a counterpart to the above
debugger UI example, I postulate a GUI drop-down list of symbols available
in-scope; this UI needs to know nothing about language semantics and automatic
imports, if the DWARF provides the correct explicit import. This suggests to
me that the DWARF should provide it.
There's also the piddly detail that debuggers are not the only consumers of
DWARF information, and presenting the DWARF in a more source-language-neutral
way (i.e., with the explicit artificial import) could be beneficial for those
other consumers, who might not necessarily want to learn language-specific
scoping rules.
No debugger will be thrown for a loop if it sees the explicit import; however
for some debuggers it would be redundant (because they implicitly import the
anonymous namespace already). There is a pretty trivial space savings if it's
omitted.
Katya has mentioned the GCC and ICC precedent; in fairness I will say GCC
didn't used to emit this, and GDB tolerated that.
Note that the DWARF standard does not tell us what to do; it merely tells us
how to emit the import, if we want to emit one. Whether we want to emit one is
up to us.
http://reviews.llvm.org/D12624
_______________________________________________
cfe-commits mailing list
cfe-commits@lists.llvm.org
http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
