c++: check completeness after auto deduction [PR80351]

Normally we check for incomplete type in start_decl, but that obviously
doesn't work for auto variables. Thanks to Pokechu22 for the analysis and
testcases:

"When cp_finish_decl calls cp_apply_type_quals_to_decl on a const auto or
constexpr auto variable, the type might not be complete the first time
(this happened when auto deduces to an initializer_list).
cp_apply_type_quals_to_decl removes the const qualifier if the type is
not complete, which is appropriate for grokdeclarator, on the assumption
that the type will be complete when called by cp_finish_decl."

	PR c++/80351

gcc/cp/ChangeLog:

	* decl.cc (cp_finish_decl): Check completeness of deduced type.

gcc/testsuite/ChangeLog:

	* g++.dg/cpp0x/constexpr-77482.C: Adjust message.
	* g++.dg/cpp1y/auto-fn27.C: Likewise.
	* g++.dg/cpp1y/lambda-generic-variadic22.C: Likewise.
	* g++.dg/cpp1z/decomp54.C: Likewise.
	* g++.dg/cpp0x/initlist-const1.C: New test.
	* g++.dg/warn/Wunused-var-37.C: New test.
	* g++.dg/warn/Wunused-var-38.C: New test.
	* g++.dg/warn/Wunused-var-39.C: New test.

diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
index 2852093..45206c2 100644 (file)
--- a/gcc/cp/decl.cc
+++ b/gcc/cp/decl.cc
@@ -8129,6 +8129,17 @@ cp_finish_decl (tree decl, tree init, bool init_const_expr_p,
          TREE_TYPE (decl) = error_mark_node;
          return;
        }
+      /* As in start_decl_1, complete so TREE_READONLY is set properly.  */
+      if (!processing_template_decl
+         && !type_uses_auto (type)
+         && !COMPLETE_TYPE_P (complete_type (type)))
+       {
+         error_at (location_of (decl),
+                   "deduced type %qT for %qD is incomplete", type, decl);
+         cxx_incomplete_type_inform (type);
+         TREE_TYPE (decl) = error_mark_node;
+         return;
+       }
       cp_apply_type_quals_to_decl (cp_type_quals (type), decl);
     }
 

diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-77482.C b/gcc/testsuite/g++.dg/cpp0x/constexpr-77482.C
index 6f5c916..bed66c7 100644 (file)
--- a/gcc/testsuite/g++.dg/cpp0x/constexpr-77482.C
+++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-77482.C
@@ -3,4 +3,4 @@
 
 constexpr auto x;      // { dg-error "declaration\[^\n\r]*has no initializer" }
 extern struct S s;
-constexpr auto y = s;  // { dg-error "has incomplete type" }
+constexpr auto y = s;  // { dg-error "incomplete" }

diff --git a/gcc/testsuite/g++.dg/cpp0x/initlist-const1.C b/gcc/testsuite/g++.dg/cpp0x/initlist-const1.C
new file mode 100644 (file)
index 0000000..de80731
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/initlist-const1.C
@@ -0,0 +1,7 @@
+// { dg-do compile { target c++11 } }
+
+#include <initializer_list>
+
+const auto x = { 1, 2 };
+
+// { dg-final { scan-assembler-not {\.data} } }

diff --git a/gcc/testsuite/g++.dg/cpp1y/auto-fn27.C b/gcc/testsuite/g++.dg/cpp1y/auto-fn27.C
index c019d9e..b22647a 100644 (file)
--- a/gcc/testsuite/g++.dg/cpp1y/auto-fn27.C
+++ b/gcc/testsuite/g++.dg/cpp1y/auto-fn27.C
@@ -31,7 +31,7 @@ F<T>::bar (const G &)
 {
   auto s = I;
   typedef decltype (s) L;
-  auto u =[&](L) { auto t = foo (J::K (), 0); }; // { dg-error "25:declared void" }
+  auto u =[&](L) { auto t = foo (J::K (), 0); }; // { dg-error "25:incomplete|void" }
 }
 struct B {
   typedef int G;

diff --git a/gcc/testsuite/g++.dg/cpp1y/lambda-generic-variadic22.C b/gcc/testsuite/g++.dg/cpp1y/lambda-generic-variadic22.C
index 670c598..9c02d07 100644 (file)
--- a/gcc/testsuite/g++.dg/cpp1y/lambda-generic-variadic22.C
+++ b/gcc/testsuite/g++.dg/cpp1y/lambda-generic-variadic22.C
@@ -4,7 +4,7 @@
 template <typename T>
 auto f (T)
 {
-  auto a = [](auto ... i)      // { dg-prune-output "incomplete type" }
+  auto a = [](auto ... i)      // { dg-prune-output "incomplete" }
   {
     int x[][i] = { 0 };                // { dg-error "not expanded" }
   }();

diff --git a/gcc/testsuite/g++.dg/cpp1z/decomp54.C b/gcc/testsuite/g++.dg/cpp1z/decomp54.C
index 1bee772..1094329 100644 (file)
--- a/gcc/testsuite/g++.dg/cpp1z/decomp54.C
+++ b/gcc/testsuite/g++.dg/cpp1z/decomp54.C
@@ -3,9 +3,9 @@
 // { dg-options "" }
 
 extern int a[];
-auto [b] { a };        // { dg-error "has incomplete type" }
+auto [b] { a };        // { dg-error "incomplete" }
                // { dg-warning "only available with" "" { target c++14_down } .-1 }
-auto [c] = a;  // { dg-error "has incomplete type" }
+auto [c] = a;  // { dg-error "incomplete" }
                // { dg-warning "only available with" "" { target c++14_down } .-1 }
 extern int d[0];
 auto [e] { d };        // { dg-error "too many initializers for" }

diff --git a/gcc/testsuite/g++.dg/warn/Wunused-var-37.C b/gcc/testsuite/g++.dg/warn/Wunused-var-37.C
new file mode 100644 (file)
index 0000000..54e76ac
--- /dev/null
+++ b/gcc/testsuite/g++.dg/warn/Wunused-var-37.C
@@ -0,0 +1,64 @@
+// Tangentially to PR c++/80351
+// { dg-do compile { target c++17 } }
+// { dg-options "-Wunused-variable" }
+#include <initializer_list>
+
+// Warnings:
+static int           int_s1  = 0; // { dg-warning "defined but not used" }
+static int           int_s2  = 0; // { dg-warning "defined but not used" }
+inline static int    int_is1 = 0; // { dg-warning "defined but not used" }
+inline static int    int_is2 = 0; // { dg-warning "defined but not used" }
+// No warnings:
+constexpr static int int_cs1 = 0; // { dg-bogus "defined but not used" }
+constexpr static int int_cs2 = 0; // { dg-bogus "defined but not used" }
+int                  int_1   = 0; // { dg-bogus "defined but not used" }
+int                  int_2   = 0; // { dg-bogus "defined but not used" }
+inline int           int_i1  = 0; // { dg-bogus "defined but not used" }
+inline int           int_i2  = 0; // { dg-bogus "defined but not used" }
+constexpr int        int_c1  = 0; // { dg-bogus "defined but not used" }
+constexpr int        int_c2  = 0; // { dg-bogus "defined but not used" }
+
+// Warnings:
+static auto           int_as1  = 0; // { dg-warning "defined but not used" }
+static auto           int_as2  = 0; // { dg-warning "defined but not used" }
+inline static auto    int_ais1 = 0; // { dg-warning "defined but not used" }
+inline static auto    int_ais2 = 0; // { dg-warning "defined but not used" }
+// No warnings:
+constexpr static auto int_acs1 = 0; // { dg-bogus "defined but not used" }
+constexpr static auto int_acs2 = 0; // { dg-bogus "defined but not used" }
+auto                  int_a1   = 0; // { dg-bogus "defined but not used" }
+auto                  int_a2   = 0; // { dg-bogus "defined but not used" }
+inline auto           int_ai1  = 0; // { dg-bogus "defined but not used" }
+inline auto           int_ai2  = 0; // { dg-bogus "defined but not used" }
+constexpr auto        int_ac1  = 0; // { dg-bogus "defined but not used" }
+constexpr auto        int_ac2  = 0; // { dg-bogus "defined but not used" }
+
+// Warnings:
+static std::initializer_list<int>           il_s1  = {0, 1}; // { dg-warning "defined but not used" }
+static std::initializer_list<int>           il_s2  = {0, 1}; // { dg-warning "defined but not used" }
+inline static std::initializer_list<int>    il_is1 = {0, 1}; // { dg-warning "defined but not used" }
+inline static std::initializer_list<int>    il_is2 = {0, 1}; // { dg-warning "defined but not used" }
+// No warnings:
+constexpr static std::initializer_list<int> il_cs1 = {0, 1}; // { dg-bogus "defined but not used" }
+constexpr static std::initializer_list<int> il_cs2 = {0, 1}; // { dg-bogus "defined but not used" }
+std::initializer_list<int>                  il_1   = {0, 1}; // { dg-bogus "defined but not used" }
+std::initializer_list<int>                  il_2   = {0, 1}; // { dg-bogus "defined but not used" }
+inline std::initializer_list<int>           il_i1  = {0, 1}; // { dg-bogus "defined but not used" }
+inline std::initializer_list<int>           il_i2  = {0, 1}; // { dg-bogus "defined but not used" }
+constexpr std::initializer_list<int>        il_c1  = {0, 1}; // { dg-bogus "defined but not used" }
+constexpr std::initializer_list<int>        il_c2  = {0, 1}; // { dg-bogus "defined but not used" }
+
+// Warnings:
+static auto           il_as1  = {0, 1}; // { dg-warning "defined but not used" }
+static auto           il_as2  = {0, 1}; // { dg-warning "defined but not used" }
+inline static auto    il_ais1 = {0, 1}; // { dg-warning "defined but not used" }
+inline static auto    il_ais2 = {0, 1}; // { dg-warning "defined but not used" }
+// No warnings:
+constexpr static auto il_acs1 = {0, 1}; // { dg-bogus "defined but not used" }
+constexpr static auto il_acs2 = {0, 1}; // { dg-bogus "defined but not used" }
+auto                  il_a1   = {0, 1}; // { dg-bogus "defined but not used" }
+auto                  il_a2   = {0, 1}; // { dg-bogus "defined but not used" }
+inline auto           il_ai1  = {0, 1}; // { dg-bogus "defined but not used" }
+inline auto           il_ai2  = {0, 1}; // { dg-bogus "defined but not used" }
+constexpr auto        il_ac1  = {0, 1}; // { dg-bogus "defined but not used" }
+constexpr auto        il_ac2  = {0, 1}; // { dg-bogus "defined but not used" }

diff --git a/gcc/testsuite/g++.dg/warn/Wunused-var-38.C b/gcc/testsuite/g++.dg/warn/Wunused-var-38.C
new file mode 100644 (file)
index 0000000..3d34bc8
--- /dev/null
+++ b/gcc/testsuite/g++.dg/warn/Wunused-var-38.C
@@ -0,0 +1,16 @@
+// PR c++/80351
+// { dg-do compile { target c++11 } }
+// { dg-options "-Wunused-variable" }
+#include <initializer_list>
+
+constexpr auto int_1 = 1; // { dg-bogus "defined but not used" }
+constexpr auto int_2 = 2; // { dg-bogus "defined but not used" }
+
+constexpr auto il_int_1 = {3, 3}; // { dg-bogus "defined but not used" "Triggered by PR80351" }
+constexpr auto il_int_2 = {4, 4}; // { dg-bogus "defined but not used" "Not triggered by PR80351" }
+
+constexpr auto il_uint_1 = {5u, 5u}; // { dg-bogus "defined but not used" "Triggered by PR80351" }
+constexpr auto il_uint_2 = {6u, 6u}; // { dg-bogus "defined but not used" "Not triggered by PR80351" }
+
+constexpr auto uint_1 = 7u; // { dg-bogus "defined but not used" }
+constexpr auto uint_2 = 8u; // { dg-bogus "defined but not used" }

diff --git a/gcc/testsuite/g++.dg/warn/Wunused-var-39.C b/gcc/testsuite/g++.dg/warn/Wunused-var-39.C
new file mode 100644 (file)
index 0000000..d25a74c
--- /dev/null
+++ b/gcc/testsuite/g++.dg/warn/Wunused-var-39.C
@@ -0,0 +1,16 @@
+// PR c++/80351
+// { dg-do compile { target c++11 } }
+// { dg-options "-Wunused-variable" }
+#include <initializer_list>
+
+const auto int_1 = 1; // { dg-bogus "defined but not used" }
+const auto int_2 = 2; // { dg-bogus "defined but not used" }
+
+const auto il_int_1 = {3, 3}; // { dg-bogus "defined but not used" "Triggered by PR80351" }
+const auto il_int_2 = {4, 4}; // { dg-bogus "defined but not used" "Not triggered by PR80351" }
+
+const auto il_uint_1 = {5u, 5u}; // { dg-bogus "defined but not used" "Triggered by PR80351" }
+const auto il_uint_2 = {6u, 6u}; // { dg-bogus "defined but not used" "Not triggered by PR80351" }
+
+const auto uint_1 = 7u; // { dg-bogus "defined but not used" }
+const auto uint_2 = 8u; // { dg-bogus "defined but not used" }