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* [gcc(refs/users/guojiufu/heads/guojiufu-branch)] c++: Fix pretty-print of pointer minus integer.
@ 2020-06-10 3:40 Jiu Fu Guo
0 siblings, 0 replies; only message in thread
From: Jiu Fu Guo @ 2020-06-10 3:40 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:5094c4400a8687dcf44f5993aee3a88e98519f3b
commit 5094c4400a8687dcf44f5993aee3a88e98519f3b
Author: Jason Merrill <jason@redhat.com>
Date: Thu Jun 4 15:56:57 2020 -0400
c++: Fix pretty-print of pointer minus integer.
For whatever reason, GCC internally represents a pointer minus an integer as
a pointer plus a very large unsigned integer. But exposing that to users is
unsightly, and it's easy enough to show the real value.
gcc/cp/ChangeLog:
* error.c (dump_binary_op): Handle negative operand to
POINTER_PLUS_EXPR.
gcc/c-family/ChangeLog:
* c-pretty-print.c (pp_c_additive_expression): Handle negative
operand to POINTER_PLUS_EXPR.
gcc/testsuite/ChangeLog:
* g++.dg/cpp0x/constexpr-ptrsub2.C: New test.
Diff:
---
gcc/c-family/c-pretty-print.c | 11 ++++++++++-
gcc/cp/error.c | 9 ++++++++-
gcc/testsuite/g++.dg/cpp0x/constexpr-ptrsub2.C | 4 ++++
3 files changed, 22 insertions(+), 2 deletions(-)
diff --git a/gcc/c-family/c-pretty-print.c b/gcc/c-family/c-pretty-print.c
index 32f30f2d452..71baf5e2ede 100644
--- a/gcc/c-family/c-pretty-print.c
+++ b/gcc/c-family/c-pretty-print.c
@@ -1898,7 +1898,16 @@ pp_c_additive_expression (c_pretty_printer *pp, tree e)
else
pp_minus (pp);
pp_c_whitespace (pp);
- pp->multiplicative_expression (TREE_OPERAND (e, 1));
+ {
+ tree op1 = TREE_OPERAND (e, 1);
+ if (code == POINTER_PLUS_EXPR
+ && TREE_CODE (op1) == INTEGER_CST
+ && tree_int_cst_sign_bit (op1))
+ /* A pointer minus an integer is represented internally as plus a very
+ large number, don't expose that to users. */
+ op1 = convert (ssizetype, op1);
+ pp->multiplicative_expression (op1);
+ }
break;
default:
diff --git a/gcc/cp/error.c b/gcc/cp/error.c
index 46970f9b699..0d6375e5e14 100644
--- a/gcc/cp/error.c
+++ b/gcc/cp/error.c
@@ -2909,7 +2909,14 @@ dump_binary_op (cxx_pretty_printer *pp, const char *opstring, tree t,
else
pp_string (pp, M_("<unknown operator>"));
pp_cxx_whitespace (pp);
- dump_expr (pp, TREE_OPERAND (t, 1), flags | TFF_EXPR_IN_PARENS);
+ tree op1 = TREE_OPERAND (t, 1);
+ if (TREE_CODE (t) == POINTER_PLUS_EXPR
+ && TREE_CODE (op1) == INTEGER_CST
+ && tree_int_cst_sign_bit (op1))
+ /* A pointer minus an integer is represented internally as plus a very
+ large number, don't expose that to users. */
+ op1 = convert (ssizetype, op1);
+ dump_expr (pp, op1, flags | TFF_EXPR_IN_PARENS);
pp_cxx_right_paren (pp);
}
diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-ptrsub2.C b/gcc/testsuite/g++.dg/cpp0x/constexpr-ptrsub2.C
new file mode 100644
index 00000000000..fd644ad7854
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-ptrsub2.C
@@ -0,0 +1,4 @@
+// { dg-do compile { target c++11 } }
+
+char c;
+constexpr char p2 = *(&c - 1); // { dg-error "-1" }
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