On 11/18/16 22:19, Jason Merrill wrote: > On 11/05/2016 12:44 PM, Bernd Edlinger wrote: >> + warning_at (DECL_SOURCE_LOCATION (newdecl), 0, >> + "declaration of %q+#D conflicts with built-in " >> + "declaration %q#D", newdecl, olddecl); > > There needs to be a way to disable this warning, even if it's enabled by > default. >
It is mostly disabled by -Wno-system-headers. So it will only warn for declarations in .cc files. Then I will probably need a better name for it. I'd like -Wbuiltin-declaration-mismatch for instance? I wonder if that should also control the C warning, and the case where the internal __builtin_ is declared differently. It is somehow hard to explain why it has to be a C++ only warning, except for historical reasons. >> - TREE_NOTHROW (olddecl) = 0; >> + TREE_NOTHROW (olddecl) = TREE_NOTHROW (newdecl); > > I still think a better fix would be to add a copy of TREE_NOTHROW to the > else block of the if (types_match), to go with the existing copies of > TREE_READONLY and TREE_THIS_VOLATILE. > I can give it a try, but I don't understand why that does apparently not give us problems with other types of declaration mismatches. It would be good to have a test case where a redeclaration with a non-builtin causes similar slightly-wrong-code issues. Possible that some hidden issues exist already, but also possible that I create new issues, if I don't understand the code completely. Is the else block ever used for non-builtin functions? Can variable declarations end up there? What other types of objects are possible there? Given that stage1 is already over, should I split the warning part from the wrong code issue? What do you think? Thanks Bernd.
