c++: strict constexpr and local vars
A change I was working on made constexpr_searcher.cc start to fail, and when I looked at it I wondered why it had been accepted before. This turned out to be because we try to be more flexible about constant-evaluation of static initializers, as allowed, but we were wrongly doing the same for non-static initializers as well. gcc/cp/ChangeLog: * constexpr.cc (maybe_constant_init_1): Only pass false for strict when initializing a variable of static duration. libstdc++-v3/ChangeLog: * testsuite/20_util/function_objects/constexpr_searcher.cc: Add constexpr. gcc/testsuite/ChangeLog: * g++.dg/cpp1y/constexpr-local4.C: New test.
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@ -8301,9 +8301,15 @@ maybe_constant_init_1 (tree t, tree decl, bool allow_non_constant,
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else if (CONSTANT_CLASS_P (t) && allow_non_constant)
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/* No evaluation needed. */;
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else
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t = cxx_eval_outermost_constant_expr (t, allow_non_constant,
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/*strict*/false,
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{
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/* [basic.start.static] allows constant-initialization of variables with
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static or thread storage duration even if it isn't required, but we
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shouldn't bend the rules the same way for automatic variables. */
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bool is_static = (decl && DECL_P (decl)
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&& (TREE_STATIC (decl) || DECL_EXTERNAL (decl)));
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t = cxx_eval_outermost_constant_expr (t, allow_non_constant, !is_static,
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manifestly_const_eval, false, decl);
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}
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if (TREE_CODE (t) == TARGET_EXPR)
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{
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tree init = TARGET_EXPR_INITIAL (t);
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@ -0,0 +1,17 @@
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// { dg-do compile { target c++14 } }
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struct A
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{
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int i;
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constexpr A(int i): i(i) {};
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};
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const A a = 42;
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constexpr int f()
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{
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const int j = a.i; // { dg-message "'a'" }
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return j;
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}
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static_assert (f() == 42,""); // { dg-error "non-constant" }
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@ -28,13 +28,13 @@
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#include <string_view>
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const std::string_view
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constexpr std::string_view
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patt = "World";
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constexpr std::string_view
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greet = "Hello, Humongous World of Wonder!!!";
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const std::wstring_view
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constexpr std::wstring_view
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wpatt = L"World";
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constexpr std::wstring_view
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