https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61886
--- Comment #34 from Zack Weinberg <zackw at panix dot com> --- > As I tried to explain, it is currently design decision to have one declaration > and one symtam node for one symbol. The one decl rule was introduced by > Codesourcery (Zack) in 2003-4. He updated frontends to avoid copying and > dropped code that dealt with duplicated declarations. Due to lack of sanity > checking some cases remained, like this one (because at that time we did not > really have proper asm name hash). There are couple open PRs since that time > that was never corrected. It's been long enough that I don't recall precisely what my goals were, but I don't think it was my intention to enforce a "one decl per asm name" rule at the time. I was trying to deal with C front-end issues: according to https://gcc.gnu.org/ml/gcc-patches/2004-01/msg00808.html, "at least bug 12267, bug 12336, bug 12373, bug 12391, bug 12560, bug 12934, bug 13129". My recollection is that the fundamental problem was getting more than one TREE_DECL object per *declared name* in -funit-at-a-time mode, which was shiny and new back then! ... Digging through the mailing list archives, maybe I'm remembering wrong. https://gcc.gnu.org/ml/gcc-patches/2004-03/msg01440.html has > The old code took the copying > approach; this was bad because it violated the basic assumption made > elsewhere in the compiler that there is exactly one DECL node for each > assembly-level symbol. Hence all the bugs. I do not remember anymore what parts of the compiler were making those assumptions, but I'm guessing it was probably the debug information generators, or mostly those. Anyhow, I don't think y'all should be taking a decision I made for the C front end under time and peer pressure (people were *really mad* at me for leaving some of those bugs unfixed for several releases in a row) in 2004 as a permanent compiler-wide design constraint ten years later :) (Note also bug 13801, and the discussion of its fix, here: https://gcc.gnu.org/ml/gcc-patches/2004-08/msg00085.html -- we wound up having to back down from the "not only is there only one DECL per assembly level symbol, it only ever accumulates information" rule that I originally wanted, due to C90 conformance problems.)
