Re: [PATCH] c++: ICE with -Wall and constexpr if [PR94937]
On 5/5/20 6:17 PM, Marek Polacek wrote: An ICE arises here because we call cp_get_callee_fndecl_nofold in a template, and we've got a CALL_EXPR whose CALL_EXPR_FN is a BASELINK. This tickles the INDIRECT_TYPE_P assert in cp_get_fndecl_from_callee. Jakub said in the PR that he'd hit a similar problem too and dealt with it in omp_declare_variant_finalize_one. I considered tweaking is_std_constant_evaluated_p to return false for a BASELINK, since the std::is_constant_evaluated call we're looking for can't be a member function, but perhaps we could get another unexpected CALL_EXPR and crash the same. In which case it might be better to make out the omp_* code into a new routine and use that, as below. Why not adjust cp_get_fndecl_from_callee to, say, return null instead of aborting when !INDIRECT_TYPE_P? As a drive-by, I'm adding a test that tests the "is_constant_evaluated in constexpr if" warning in a template too. Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk/10.2? PR c++/94937 * cp-tree.h (cp_get_callee_fndecl_template): Declare. * cvt.c (cp_get_callee_fndecl_template): New. * decl.c (omp_declare_variant_finalize_one): Use cp_get_callee_fndecl_template. * semantics.c (is_std_constant_evaluated_p): Call cp_get_callee_fndecl_template instead of cp_get_callee_fndecl_nofold. * g++.dg/cpp1z/constexpr-if34.C: New test. * g++.dg/cpp2a/is-constant-evaluated10.C: New test. --- gcc/cp/cp-tree.h | 1 + gcc/cp/cvt.c | 17 +++ gcc/cp/decl.c | 12 +--- gcc/cp/semantics.c| 2 +- gcc/testsuite/g++.dg/cpp1z/constexpr-if34.C | 15 ++ .../g++.dg/cpp2a/is-constant-evaluated10.C| 30 +++ 6 files changed, 65 insertions(+), 12 deletions(-) create mode 100644 gcc/testsuite/g++.dg/cpp1z/constexpr-if34.C create mode 100644 gcc/testsuite/g++.dg/cpp2a/is-constant-evaluated10.C diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h index c4b81428e14..ecee0f479b0 100644 --- a/gcc/cp/cp-tree.h +++ b/gcc/cp/cp-tree.h @@ -6477,6 +6477,7 @@ extern tree cp_fold_convert (tree, tree); extern tree cp_get_callee (tree); extern tree cp_get_callee_fndecl (tree); extern tree cp_get_callee_fndecl_nofold (tree); +extern tree cp_get_callee_fndecl_template (tree); extern tree cp_get_fndecl_from_callee (tree, bool fold = true); extern tree convert_to_void (tree, impl_conv_void, tsubst_flags_t); diff --git a/gcc/cp/cvt.c b/gcc/cp/cvt.c index 656e7fd3ec0..5d3fba76bb9 100644 --- a/gcc/cp/cvt.c +++ b/gcc/cp/cvt.c @@ -1027,6 +1027,23 @@ cp_get_callee_fndecl_nofold (tree call) return cp_get_fndecl_from_callee (cp_get_callee (call), false); } +/* As above, but is safe to call in a template too where we might get + unexpected trees. Returns the FUNCTION_DECL or NULL_TREE. */ + +tree +cp_get_callee_fndecl_template (tree call) +{ + call = cp_get_callee (call); + if (call == NULL_TREE) +return NULL_TREE; + else if (TREE_CODE (call) == FUNCTION_DECL) +return call; + else if (TREE_TYPE (call) && INDIRECT_TYPE_P (TREE_TYPE (call))) +return cp_get_fndecl_from_callee (call, /*fold=*/false); + else +return NULL_TREE; +} + /* Subroutine of convert_to_void. Warn if we're discarding something with attribute [[nodiscard]]. */ diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c index 3e7ed98fed3..7b63304ebf3 100644 --- a/gcc/cp/decl.c +++ b/gcc/cp/decl.c @@ -7297,17 +7297,7 @@ omp_declare_variant_finalize_one (tree decl, tree attr) if (variant == error_mark_node && !processing_template_decl) return true; - variant = cp_get_callee (variant); - if (variant) -{ - if (TREE_CODE (variant) == FUNCTION_DECL) - ; - else if (TREE_TYPE (variant) && INDIRECT_TYPE_P (TREE_TYPE (variant))) - variant = cp_get_fndecl_from_callee (variant, false); - else - variant = NULL_TREE; -} - + variant = cp_get_callee_fndecl_template (variant); input_location = save_loc; if (variant) diff --git a/gcc/cp/semantics.c b/gcc/cp/semantics.c index 4d1592ab0d2..716ee48446d 100644 --- a/gcc/cp/semantics.c +++ b/gcc/cp/semantics.c @@ -734,7 +734,7 @@ is_std_constant_evaluated_p (tree fn) if (call_expr_nargs (fn) != 0) return false; - tree fndecl = cp_get_callee_fndecl_nofold (fn); + tree fndecl = cp_get_callee_fndecl_template (fn); if (fndecl == NULL_TREE) return false; diff --git a/gcc/testsuite/g++.dg/cpp1z/constexpr-if34.C b/gcc/testsuite/g++.dg/cpp1z/constexpr-if34.C new file mode 100644 index 000..6e0b2597a53 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp1z/constexpr-if34.C @@ -0,0 +1,15 @@ +// PR c++/94937 - ICE with -Wall and constexpr
[PATCH] c++: ICE with -Wall and constexpr if [PR94937]
An ICE arises here because we call cp_get_callee_fndecl_nofold in a template, and we've got a CALL_EXPR whose CALL_EXPR_FN is a BASELINK. This tickles the INDIRECT_TYPE_P assert in cp_get_fndecl_from_callee. Jakub said in the PR that he'd hit a similar problem too and dealt with it in omp_declare_variant_finalize_one. I considered tweaking is_std_constant_evaluated_p to return false for a BASELINK, since the std::is_constant_evaluated call we're looking for can't be a member function, but perhaps we could get another unexpected CALL_EXPR and crash the same. In which case it might be better to make out the omp_* code into a new routine and use that, as below. As a drive-by, I'm adding a test that tests the "is_constant_evaluated in constexpr if" warning in a template too. Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk/10.2? PR c++/94937 * cp-tree.h (cp_get_callee_fndecl_template): Declare. * cvt.c (cp_get_callee_fndecl_template): New. * decl.c (omp_declare_variant_finalize_one): Use cp_get_callee_fndecl_template. * semantics.c (is_std_constant_evaluated_p): Call cp_get_callee_fndecl_template instead of cp_get_callee_fndecl_nofold. * g++.dg/cpp1z/constexpr-if34.C: New test. * g++.dg/cpp2a/is-constant-evaluated10.C: New test. --- gcc/cp/cp-tree.h | 1 + gcc/cp/cvt.c | 17 +++ gcc/cp/decl.c | 12 +--- gcc/cp/semantics.c| 2 +- gcc/testsuite/g++.dg/cpp1z/constexpr-if34.C | 15 ++ .../g++.dg/cpp2a/is-constant-evaluated10.C| 30 +++ 6 files changed, 65 insertions(+), 12 deletions(-) create mode 100644 gcc/testsuite/g++.dg/cpp1z/constexpr-if34.C create mode 100644 gcc/testsuite/g++.dg/cpp2a/is-constant-evaluated10.C diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h index c4b81428e14..ecee0f479b0 100644 --- a/gcc/cp/cp-tree.h +++ b/gcc/cp/cp-tree.h @@ -6477,6 +6477,7 @@ extern tree cp_fold_convert (tree, tree); extern tree cp_get_callee (tree); extern tree cp_get_callee_fndecl (tree); extern tree cp_get_callee_fndecl_nofold(tree); +extern tree cp_get_callee_fndecl_template (tree); extern tree cp_get_fndecl_from_callee (tree, bool fold = true); extern tree convert_to_void(tree, impl_conv_void, tsubst_flags_t); diff --git a/gcc/cp/cvt.c b/gcc/cp/cvt.c index 656e7fd3ec0..5d3fba76bb9 100644 --- a/gcc/cp/cvt.c +++ b/gcc/cp/cvt.c @@ -1027,6 +1027,23 @@ cp_get_callee_fndecl_nofold (tree call) return cp_get_fndecl_from_callee (cp_get_callee (call), false); } +/* As above, but is safe to call in a template too where we might get + unexpected trees. Returns the FUNCTION_DECL or NULL_TREE. */ + +tree +cp_get_callee_fndecl_template (tree call) +{ + call = cp_get_callee (call); + if (call == NULL_TREE) +return NULL_TREE; + else if (TREE_CODE (call) == FUNCTION_DECL) +return call; + else if (TREE_TYPE (call) && INDIRECT_TYPE_P (TREE_TYPE (call))) +return cp_get_fndecl_from_callee (call, /*fold=*/false); + else +return NULL_TREE; +} + /* Subroutine of convert_to_void. Warn if we're discarding something with attribute [[nodiscard]]. */ diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c index 3e7ed98fed3..7b63304ebf3 100644 --- a/gcc/cp/decl.c +++ b/gcc/cp/decl.c @@ -7297,17 +7297,7 @@ omp_declare_variant_finalize_one (tree decl, tree attr) if (variant == error_mark_node && !processing_template_decl) return true; - variant = cp_get_callee (variant); - if (variant) -{ - if (TREE_CODE (variant) == FUNCTION_DECL) - ; - else if (TREE_TYPE (variant) && INDIRECT_TYPE_P (TREE_TYPE (variant))) - variant = cp_get_fndecl_from_callee (variant, false); - else - variant = NULL_TREE; -} - + variant = cp_get_callee_fndecl_template (variant); input_location = save_loc; if (variant) diff --git a/gcc/cp/semantics.c b/gcc/cp/semantics.c index 4d1592ab0d2..716ee48446d 100644 --- a/gcc/cp/semantics.c +++ b/gcc/cp/semantics.c @@ -734,7 +734,7 @@ is_std_constant_evaluated_p (tree fn) if (call_expr_nargs (fn) != 0) return false; - tree fndecl = cp_get_callee_fndecl_nofold (fn); + tree fndecl = cp_get_callee_fndecl_template (fn); if (fndecl == NULL_TREE) return false; diff --git a/gcc/testsuite/g++.dg/cpp1z/constexpr-if34.C b/gcc/testsuite/g++.dg/cpp1z/constexpr-if34.C new file mode 100644 index 000..6e0b2597a53 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp1z/constexpr-if34.C @@ -0,0 +1,15 @@ +// PR c++/94937 - ICE with -Wall and constexpr if. +// { dg-do compile { target c++17 } } +// { dg-options "-Wall" } + +struct B { + static constexpr bool foo() { return false; } +}; + +template +struct C { + static void bar ()