On Tue, Jan 29, 2019 at 09:40:18PM -0500, Jason Merrill wrote:
> On Tue, Jan 29, 2019 at 6:53 PM Marek Polacek <pola...@redhat.com> wrote:
> >
> > My recent patch for 88815 and 78244 caused 89083, a P1 9 regression, which
> > happens to be the same problem as 80864 and its many dupes, something I'd
> > been meaning to fix for a long time.
> >
> > Basically, the problem is repeated reshaping of a constructor, once when
> > parsing, and then again when substituting. With the recent fix, we call
> > reshape_init + digest_init in finish_compound_literal even in a template
> > if the expression is not instantiation-dependent, and then again when
> > tsubst_*.
> >
> > For instance, in initlist107.C, when parsing a functional cast, we call
> > finish_compound_literal which calls reshape_init, which turns
> >
> > { NON_LVALUE_EXPR<1>, NON_LVALUE_EXPR<2> }
> >
> > into
> >
> > { { NON_LVALUE_EXPR<1>, NON_LVALUE_EXPR<2> } }
> >
> > and then digest_init turns that into
> >
> > { .x = { 1, 2 } }
> >
> > which is a compound literal (TREE_HAS_CONSTRUCTOR set), but the
> > subexpression
> > "{ 1, 2 }" isn't. "{ 1, 2 }" will now have the type int[3], so it's not
> > BRACE_ENCLOSED_INITIALIZER_P.
> >
> > And then tsubst_* processes "{ .x = { 1, 2 } }". The case CONSTRUCTOR
> > in tsubst_copy_and_build will call finish_compound_literal on a copy of
> > "{ 1, 2 }" wrapped in a new { }, because the whole expr has
> > TREE_HAS_CONSTRUCTOR.
> > That crashes in reshape_init_r in the
> > 6155 if (TREE_CODE (stripped_init) == CONSTRUCTOR)
> > block; we have a constructor, it's not COMPOUND_LITERAL_P, and because
> > digest_init had given it the type int[3], we hit
> > 6172 gcc_assert (BRACE_ENCLOSED_INITIALIZER_P
> > (stripped_init));
> >
> > As expand_default_init explains in a comment, a CONSTRUCTOR of the target's
> > type
> > is a previously digested initializer, so we should probably do a similar
> > trick
> > here. This fixes all the variants of the problem I've come up with.
> >
> > 80864 is a similar case, we reshape when parsing and then second time in
> > fold_non_dependent_expr called from store_init_value, because of the
> > 'constexpr'.
> >
> > Also update a stale comment.
> >
> > Bootstrapped/regtest running on x86_64-linux, ok for trunk and 8 after a
> > while?
> >
> > 2019-01-29 Marek Polacek <pola...@redhat.com>
> >
> > PR c++/89083, c++/80864 - ICE with list initialization in template.
> > * decl.c (reshape_init_r): Don't reshape a digested initializer.
> >
> > * g++.dg/cpp0x/initlist107.C: New test.
> > * g++.dg/cpp0x/initlist108.C: New test.
> > * g++.dg/cpp0x/initlist109.C: New test.
> >
> > diff --git gcc/cp/decl.c gcc/cp/decl.c
> > index 79eeac177b6..da08ecc21aa 100644
> > --- gcc/cp/decl.c
> > +++ gcc/cp/decl.c
> > @@ -6161,11 +6161,17 @@ reshape_init_r (tree type, reshape_iter *d, bool
> > first_initializer_p,
> > ;
> > else if (COMPOUND_LITERAL_P (stripped_init))
> > /* For a nested compound literal, there is no need to reshape
> > since
> > - brace elision is not allowed. Even if we decided to allow it,
> > - we should add a call to reshape_init in
> > finish_compound_literal,
> > - before calling digest_init, so changing this code would still
> > - not be necessary. */
> > + we called reshape_init in finish_compound_literal, before
> > calling
> > + digest_init. */
> > gcc_assert (!BRACE_ENCLOSED_INITIALIZER_P (stripped_init));
> > + /* Similarly, a CONSTRUCTOR of the target's type is a previously
> > + digested initializer. */
> > + else if (same_type_ignoring_top_level_qualifiers_p (type,
> > + TREE_TYPE
> > (init)))
>
> Hmm, aren't both of these tests true for a dependent compound literal,
> which won't have been reshaped already?
I'm hoping that can't happen, but it's a good question. When we have a
dependent compound literal, finish_compound_literal just sets
TREE_HAS_CONSTRUCTOR and returns it, so then in tsubst_*, after substituting
each element of the constructor, we call finish_compound_literal. The
constructor is no longer dependent and since we operate on a copy on which
we didn't set TREE_HAS_CONSTRUCTOR, the first condition shouldn't be true.
And the second condition should also never be true for a compound literal
that hasn't been reshaped, because digest_init is only ever called after
reshape_init (and the comment for digest_init_r says it assumes that
reshape_init has already run). The type of a CONSTRUCTOR can also by changed
in tsubst_copy_and_build:
19269 TREE_TYPE (r) = type;
but I haven't been able to trigger any problem yet. Worst comes to worst this
patch changes the ICE to another ICE, but I'm not finding a testcase.
The following patch is the same but adds tests with dependent compound literals
for good measure.
Bootstrapped/regtested on x86_64-linux, ok for trunk?
2019-01-30 Marek Polacek <pola...@redhat.com>
PR c++/89083, c++/80864 - ICE with list initialization in template.
* decl.c (reshape_init_r): Don't reshape a digested initializer.
* g++.dg/cpp0x/initlist107.C: New test.
* g++.dg/cpp0x/initlist108.C: New test.
* g++.dg/cpp0x/initlist109.C: New test.
* g++.dg/cpp0x/initlist110.C: New test.
* g++.dg/cpp0x/initlist111.C: New test.
* g++.dg/cpp0x/initlist112.C: New test.
diff --git gcc/cp/decl.c gcc/cp/decl.c
index 79eeac177b6..da08ecc21aa 100644
--- gcc/cp/decl.c
+++ gcc/cp/decl.c
@@ -6161,11 +6161,17 @@ reshape_init_r (tree type, reshape_iter *d, bool
first_initializer_p,
;
else if (COMPOUND_LITERAL_P (stripped_init))
/* For a nested compound literal, there is no need to reshape since
- brace elision is not allowed. Even if we decided to allow it,
- we should add a call to reshape_init in finish_compound_literal,
- before calling digest_init, so changing this code would still
- not be necessary. */
+ we called reshape_init in finish_compound_literal, before calling
+ digest_init. */
gcc_assert (!BRACE_ENCLOSED_INITIALIZER_P (stripped_init));
+ /* Similarly, a CONSTRUCTOR of the target's type is a previously
+ digested initializer. */
+ else if (same_type_ignoring_top_level_qualifiers_p (type,
+ TREE_TYPE (init)))
+ {
+ ++d->cur;
+ return init;
+ }
else
{
++d->cur;
diff --git gcc/testsuite/g++.dg/cpp0x/initlist107.C
gcc/testsuite/g++.dg/cpp0x/initlist107.C
new file mode 100644
index 00000000000..9acfe7cb267
--- /dev/null
+++ gcc/testsuite/g++.dg/cpp0x/initlist107.C
@@ -0,0 +1,24 @@
+// PR c++/89083
+// { dg-do compile { target c++11 } }
+// { dg-options "-Wmissing-braces" }
+
+struct A { int x[3]; };
+
+template<class T>
+decltype(A{1, 2}, T()) fn1(T t) // { dg-warning "missing braces" }
+{
+ return t;
+}
+
+template<class T>
+decltype(A{{1, 2}}, T()) fn2(T t)
+{
+ return t;
+}
+
+void
+f()
+{
+ fn1(1);
+ fn2(1);
+}
diff --git gcc/testsuite/g++.dg/cpp0x/initlist108.C
gcc/testsuite/g++.dg/cpp0x/initlist108.C
new file mode 100644
index 00000000000..e2839787fa5
--- /dev/null
+++ gcc/testsuite/g++.dg/cpp0x/initlist108.C
@@ -0,0 +1,34 @@
+// PR c++/80864
+// { dg-do compile { target c++11 } }
+// { dg-options "-Wmissing-braces" }
+
+struct S {
+ char c[1];
+};
+
+template <typename T>
+void
+fn ()
+{
+ constexpr S s1 = S{};
+ constexpr S s2 = S{{}};
+ constexpr S s3 = S{{{}}};
+ constexpr S s4 = {};
+ constexpr S s5 = {{}};
+ constexpr S s6 = {{{}}};
+ constexpr S s7{{}};
+ constexpr S s8{S{}};
+ constexpr S s9{S{{}}};
+ constexpr S s10{S{{{}}}};
+ constexpr S s11 = S();
+ constexpr S s12 = S({});
+ constexpr S s13 = S({{}});
+ constexpr S s14 = {{}};
+ constexpr S s15 = {{{}}};
+}
+
+void
+foo ()
+{
+ fn<int>();
+}
diff --git gcc/testsuite/g++.dg/cpp0x/initlist109.C
gcc/testsuite/g++.dg/cpp0x/initlist109.C
new file mode 100644
index 00000000000..1351a2d57ce
--- /dev/null
+++ gcc/testsuite/g++.dg/cpp0x/initlist109.C
@@ -0,0 +1,15 @@
+// PR c++/80864
+// { dg-do compile { target c++11 } }
+// { dg-options "-Wmissing-braces" }
+
+struct S {};
+struct A { S s[1]; };
+
+template <typename>
+struct R { static constexpr auto h = A{S{}}; }; // { dg-warning "missing
braces" }
+
+template <typename>
+struct R2 { static constexpr auto h = A{{S{}}}; };
+
+A foo = R<int>::h;
+A foo2 = R2<int>::h;
diff --git gcc/testsuite/g++.dg/cpp0x/initlist110.C
gcc/testsuite/g++.dg/cpp0x/initlist110.C
new file mode 100644
index 00000000000..7bb229cbc7e
--- /dev/null
+++ gcc/testsuite/g++.dg/cpp0x/initlist110.C
@@ -0,0 +1,32 @@
+// PR c++/89083
+// { dg-do compile { target c++11 } }
+
+struct C { int a[3]; int i; };
+struct B { C c[3]; };
+struct A { B b[3]; };
+
+template<class T, int N>
+decltype(A{N, N}, T()) fn1(T t)
+{
+ return t;
+}
+
+template<class T, int N>
+decltype(A{{{N, N, N}, {N + 1}}}, T()) fn2(T t)
+{
+ return t;
+}
+
+template<class T, int N, int M>
+decltype(A{{N + M}}, T()) fn3(T t)
+{
+ return t;
+}
+
+void
+f()
+{
+ fn1<int, 10>(1);
+ fn2<int, 10>(1);
+ fn3<int, 10, 20>(1);
+}
diff --git gcc/testsuite/g++.dg/cpp0x/initlist111.C
gcc/testsuite/g++.dg/cpp0x/initlist111.C
new file mode 100644
index 00000000000..7f96115e618
--- /dev/null
+++ gcc/testsuite/g++.dg/cpp0x/initlist111.C
@@ -0,0 +1,32 @@
+// PR c++/80864
+// { dg-do compile { target c++11 } }
+
+struct S {
+ int c[3];
+};
+
+template <typename T, int N>
+void
+fn ()
+{
+ constexpr S s1 = S{N};
+ constexpr S s2 = S{{N, N}};
+ constexpr S s3 = S{N, N};
+ constexpr S s4 = {N};
+ constexpr S s5 = {{N}};
+ constexpr S s6 = {N, N};
+ constexpr S s7{{N}};
+ constexpr S s8{S{N}};
+ constexpr S s9{S{{N}}};
+ constexpr S s10{S{{N}}};
+ constexpr S s11 = S({N});
+ constexpr S s12 = S({{N}});
+ constexpr S s13 = {{N}};
+ constexpr S s14 = {{N, N, N}};
+}
+
+void
+foo ()
+{
+ fn<int, 10>();
+}
diff --git gcc/testsuite/g++.dg/cpp0x/initlist112.C
gcc/testsuite/g++.dg/cpp0x/initlist112.C
new file mode 100644
index 00000000000..cd97098eec5
--- /dev/null
+++ gcc/testsuite/g++.dg/cpp0x/initlist112.C
@@ -0,0 +1,14 @@
+// PR c++/80864
+// { dg-do compile { target c++11 } }
+
+struct S {int a[2]; };
+struct A { S s[1]; };
+
+template <typename, int N>
+struct R { static constexpr auto h = A{S{N}}; };
+
+template <typename, int N>
+struct R2 { static constexpr auto h = A{S{{N, N}}}; };
+
+A foo = R<int, 10>::h;
+A foo2 = R2<int, 10>::h;
