Now that we resolve non-dependent variable template-ids ahead of time, cp_finish_decl needs to handle a new invalid situation: we can end up trying to instantiate a variable template with deduced return type before we fully parsed (and attached) its initializer.
Bootstrapped and regtested on x86_64-pc-linux-gnu, does this OK for trunK? PR c++/109300 gcc/cp/ChangeLog: * decl.cc (cp_finish_decl): Diagnose ordinary auto deduction with no initializer instead of asserting. gcc/testsuite/ChangeLog: * g++.dg/cpp1y/var-templ79.C: New test. --- gcc/cp/decl.cc | 15 ++++++++++++++- gcc/testsuite/g++.dg/cpp1y/var-templ79.C | 5 +++++ 2 files changed, 19 insertions(+), 1 deletion(-) create mode 100644 gcc/testsuite/g++.dg/cpp1y/var-templ79.C diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc index 20b980f68c8..2c91693b99d 100644 --- a/gcc/cp/decl.cc +++ b/gcc/cp/decl.cc @@ -8276,7 +8276,20 @@ cp_finish_decl (tree decl, tree init, bool init_const_expr_p, return; } - gcc_assert (CLASS_PLACEHOLDER_TEMPLATE (auto_node)); + if (CLASS_PLACEHOLDER_TEMPLATE (auto_node)) + /* Class deduction with no initializer is OK. */; + else + { + /* Ordinary auto deduction without an initializer, a situation + which grokdeclarator already catches and rejects for the most + part. But we can still get here if we're instantiating a + variable template before we've fully parsed (and attached) its + initializer, e.g. template<class> auto x = x<int>; */ + error_at (DECL_SOURCE_LOCATION (decl), + "declaration of %q#D has no initializer", decl); + TREE_TYPE (decl) = error_mark_node; + return; + } } d_init = init; if (d_init) diff --git a/gcc/testsuite/g++.dg/cpp1y/var-templ79.C b/gcc/testsuite/g++.dg/cpp1y/var-templ79.C new file mode 100644 index 00000000000..3c0d276153a --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp1y/var-templ79.C @@ -0,0 +1,5 @@ +// PR c++/109300 +// { dg-do compile { target c++14 } } + +template<class> +auto x = x<int>; // { dg-error "" } -- 2.40.0.130.g27d43aaaf5