This patch adds a new warning option: Winaccessible-base, so that
users are able to selectively control the warning. The warning is
enabled by default; however, for the virtual bases' warning, it only
triggers with -Wextra flag.
Bootstrapped/regtested on x86_64-linux, ok for trunk?
2019-06-07 Matthew Beliveau <mbeli...@redhat.com>
PR c++/90449 - add -Winaccessible-base option.
* doc/invoke.texi (Winaccessible-base): Document.
* c.opt (Winaccessible-base): Added new option.
* class.c (warn_about_ambiguous_bases): Implemented new
Winaccessible-base warning option for both direct and virtual
base warnings.
* g++.dg/warn/Winaccessible-base-1.C: New file.
* g++.dg/warn/Winaccessible-base-2.C: New file.
* g++.dg/warn/Winaccessible-virtual-base-1.C: New file.
* g++.dg/warn/Winaccessible-virtual-base-2.C: New file.
diff --git gcc/c-family/c.opt gcc/c-family/c.opt
index 046d489f7eb..144f6da15d6 100644
--- gcc/c-family/c.opt
+++ gcc/c-family/c.opt
@@ -625,6 +625,10 @@ Wignored-attributes
C C++ Var(warn_ignored_attributes) Init(1) Warning
Warn whenever attributes are ignored.
+Winaccessible-base
+C++ ObjC++ Var(warn_inaccessible_base) Init(1) Warning
+Warn when a base is inaccessible in derived due to ambiguity.
+
Wincompatible-pointer-types
C ObjC Var(warn_incompatible_pointer_types) Init(1) Warning
Warn when there is a conversion between pointers that have incompatible types.
diff --git gcc/cp/class.c gcc/cp/class.c
index a2585a61f96..0f26b34e38e 100644
--- gcc/cp/class.c
+++ gcc/cp/class.c
@@ -6025,6 +6025,10 @@ warn_about_ambiguous_bases (tree t)
tree binfo;
tree base_binfo;
+ /* If not checking for warning then return early. */
+ if (!warn_inaccessible_base)
+ return;
+
/* If there are no repeated bases, nothing can be ambiguous. */
if (!CLASSTYPE_REPEATED_BASE_P (t))
return;
@@ -6036,8 +6040,8 @@ warn_about_ambiguous_bases (tree t)
basetype = BINFO_TYPE (base_binfo);
if (!uniquely_derived_from_p (basetype, t))
- warning (0, "direct base %qT inaccessible in %qT due to ambiguity",
- basetype, t);
+ warning (OPT_Winaccessible_base, "direct base %qT inaccessible "
+ "in %qT due to ambiguity", basetype, t);
}
/* Check for ambiguous virtual bases. */
@@ -6048,8 +6052,8 @@ warn_about_ambiguous_bases (tree t)
basetype = BINFO_TYPE (binfo);
if (!uniquely_derived_from_p (basetype, t))
- warning (OPT_Wextra, "virtual base %qT inaccessible in %qT due "
- "to ambiguity", basetype, t);
+ warning (OPT_Winaccessible_base, "virtual base %qT inaccessible in "
+ "%qT due to ambiguity", basetype, t);
}
}
diff --git gcc/doc/invoke.texi gcc/doc/invoke.texi
index 3e4f012b4fa..862ee794773 100644
--- gcc/doc/invoke.texi
+++ gcc/doc/invoke.texi
@@ -317,6 +317,7 @@ Objective-C and Objective-C++ Dialects}.
-Wignored-qualifiers -Wignored-attributes -Wincompatible-pointer-types @gol
-Wimplicit -Wimplicit-fallthrough -Wimplicit-fallthrough=@var{n} @gol
-Wimplicit-function-declaration -Wimplicit-int @gol
+-Winaccessible-base @gol
-Winit-self -Winline -Wno-int-conversion -Wint-in-bool-context @gol
-Wno-int-to-pointer-cast -Winvalid-memory-model -Wno-invalid-offsetof @gol
-Winvalid-pch -Wlarger-than=@var{byte-size} @gol
@@ -4800,6 +4801,22 @@ is only active when @option{-fdelete-null-pointer-checks} is active,
which is enabled by optimizations in most targets. The precision of
the warnings depends on the optimization options used.
+@item -Winaccessible-base @r{(C++, Objective-C++ only)}
+@opindex Winaccessible-base
+@opindex Wno-inaccessible-base
+Warn when a base is inaccessible in derived due to ambiguity. The warning is
+enabled by default. Note the warning for virtual bases is enabled by the
+@option{-Wextra} option.
+@smallexample
+@group
+struct A @{ int a; @};
+
+struct B : A @{ @};
+
+struct C : B, A @{ @};
+@end group
+@end smallexample
+
@item -Winit-self @r{(C, C++, Objective-C and Objective-C++ only)}
@opindex Winit-self
@opindex Wno-init-self
diff --git gcc/testsuite/g++.dg/warn/Winaccessible-base-1.C gcc/testsuite/g++.dg/warn/Winaccessible-base-1.C
new file mode 100644
index 00000000000..2e32b0b119f
--- /dev/null
+++ gcc/testsuite/g++.dg/warn/Winaccessible-base-1.C
@@ -0,0 +1,7 @@
+// PR c++/90449
+
+struct A { int a; };
+
+struct B : A { };
+
+struct C : B, A { }; // { dg-warning "direct base 'A' inaccessible in 'C' due to ambiguity" }
diff --git gcc/testsuite/g++.dg/warn/Winaccessible-base-2.C gcc/testsuite/g++.dg/warn/Winaccessible-base-2.C
new file mode 100644
index 00000000000..67bd740a763
--- /dev/null
+++ gcc/testsuite/g++.dg/warn/Winaccessible-base-2.C
@@ -0,0 +1,8 @@
+// PR c++/90449
+// { dg-options -Wno-inaccessible-base }
+
+struct A { int a; };
+
+struct B : A { };
+
+struct C : B, A { }; // { dg-bogus "direct base 'A' inaccessible in 'C' due to ambiguity" }
diff --git gcc/testsuite/g++.dg/warn/Winaccessible-virtual-base-1.C gcc/testsuite/g++.dg/warn/Winaccessible-virtual-base-1.C
new file mode 100644
index 00000000000..051fcc695fe
--- /dev/null
+++ gcc/testsuite/g++.dg/warn/Winaccessible-virtual-base-1.C
@@ -0,0 +1,10 @@
+// PR c++/90449
+// { dg-options -Wextra }
+
+struct A { };
+
+struct B : virtual A { };
+
+struct C : A { };
+
+struct D : B, C { }; // { dg-warning "virtual base 'A' inaccessible in 'D' due to ambiguity" }
diff --git gcc/testsuite/g++.dg/warn/Winaccessible-virtual-base-2.C gcc/testsuite/g++.dg/warn/Winaccessible-virtual-base-2.C
new file mode 100644
index 00000000000..eab9ec0e3d7
--- /dev/null
+++ gcc/testsuite/g++.dg/warn/Winaccessible-virtual-base-2.C
@@ -0,0 +1,10 @@
+// PR c++/90449
+// { dg-options "-Wextra -Wno-inaccessible-base" }
+
+struct A { };
+
+struct B : virtual A { };
+
+struct C : A { };
+
+struct D : B, C { }; // { dg-bogus "virtual base 'A' inaccessible in 'D' due to ambiguity" }
