193 lines
6.9 KiB
Diff
193 lines
6.9 KiB
Diff
From 7d3f53c595e1766ca0494e5f56f33b0ce49b3bb4 Mon Sep 17 00:00:00 2001
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From: Martin Sebor <msebor@redhat.com>
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Date: Thu, 15 Jul 2021 10:11:23 -0600
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Subject: [PATCH] Avoid -Wvla-parameter for nontrivial bounds [PR97548].
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Resolves:
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PR c/101289 - bogus -Wvla-paramater warning when using const for vla param
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PR c/97548 - bogus -Wvla-parameter on a bound expression involving a parameter
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gcc/c-family/ChangeLog:
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PR c/101289
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PR c/97548
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* c-warn.c (warn_parm_array_mismatch): Use OEP_DECL_NAME.
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gcc/c/ChangeLog:
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PR c/101289
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PR c/97548
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* c-decl.c (get_parm_array_spec): Strip nops.
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gcc/ChangeLog:
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PR c/101289
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PR c/97548
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* fold-const.c (operand_compare::operand_equal_p): Handle OEP_DECL_NAME.
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(operand_compare::verify_hash_value): Same.
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* tree-core.h (OEP_DECL_NAME): New.
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gcc/testsuite/ChangeLog:
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* gcc.dg/Wvla-parameter-12.c: New test.
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---
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gcc/c-family/c-warn.c | 3 +-
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gcc/c/c-decl.c | 1 +
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gcc/fold-const.c | 33 ++++++++++++++++------
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gcc/testsuite/gcc.dg/Wvla-parameter-12.c | 36 ++++++++++++++++++++++++
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gcc/tree-core.h | 7 ++++-
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5 files changed, 69 insertions(+), 11 deletions(-)
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create mode 100644 gcc/testsuite/gcc.dg/Wvla-parameter-12.c
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diff --git a/gcc/c-family/c-warn.c b/gcc/c-family/c-warn.c
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index 7414063aa11..250da89a829 100644
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--- a/gcc/c-family/c-warn.c
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+++ b/gcc/c-family/c-warn.c
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@@ -3646,7 +3646,8 @@ warn_parm_array_mismatch (location_t origloc, tree fndecl, tree newparms)
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/* The VLA bounds don't refer to other function parameters.
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Compare them lexicographically to detect gross mismatches
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such as between T[foo()] and T[bar()]. */
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- if (operand_equal_p (newbnd, curbnd, OEP_LEXICOGRAPHIC))
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+ if (operand_equal_p (newbnd, curbnd,
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+ OEP_DECL_NAME | OEP_LEXICOGRAPHIC))
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continue;
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if (warning_at (newloc, OPT_Wvla_parameter,
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diff --git a/gcc/c/c-decl.c b/gcc/c/c-decl.c
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index 53b2b5b637d..ddef9c68fb7 100644
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--- a/gcc/c/c-decl.c
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+++ b/gcc/c/c-decl.c
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@@ -5862,6 +5862,7 @@ get_parm_array_spec (const struct c_parm *parm, tree attrs)
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/* Each variable VLA bound is represented by a dollar sign. */
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spec += "$";
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+ STRIP_NOPS (nelts);
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vbchain = tree_cons (NULL_TREE, nelts, vbchain);
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}
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diff --git a/gcc/fold-const.c b/gcc/fold-const.c
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index a1d08c74025..f5c19a0cfd4 100644
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--- a/gcc/fold-const.c
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+++ b/gcc/fold-const.c
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@@ -3506,11 +3506,26 @@ operand_compare::operand_equal_p (const_tree arg0, const_tree arg1,
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case tcc_declaration:
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/* Consider __builtin_sqrt equal to sqrt. */
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- return (TREE_CODE (arg0) == FUNCTION_DECL
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- && fndecl_built_in_p (arg0) && fndecl_built_in_p (arg1)
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- && DECL_BUILT_IN_CLASS (arg0) == DECL_BUILT_IN_CLASS (arg1)
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- && (DECL_UNCHECKED_FUNCTION_CODE (arg0)
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- == DECL_UNCHECKED_FUNCTION_CODE (arg1)));
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+ if (TREE_CODE (arg0) == FUNCTION_DECL)
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+ return (fndecl_built_in_p (arg0) && fndecl_built_in_p (arg1)
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+ && DECL_BUILT_IN_CLASS (arg0) == DECL_BUILT_IN_CLASS (arg1)
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+ && (DECL_UNCHECKED_FUNCTION_CODE (arg0)
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+ == DECL_UNCHECKED_FUNCTION_CODE (arg1)));
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+
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+ if (DECL_P (arg0)
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+ && (flags & OEP_DECL_NAME)
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+ && (flags & OEP_LEXICOGRAPHIC))
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+ {
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+ /* Consider decls with the same name equal. The caller needs
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+ to make sure they refer to the same entity (such as a function
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+ formal parameter). */
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+ tree a0name = DECL_NAME (arg0);
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+ tree a1name = DECL_NAME (arg1);
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+ const char *a0ns = a0name ? IDENTIFIER_POINTER (a0name) : NULL;
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+ const char *a1ns = a1name ? IDENTIFIER_POINTER (a1name) : NULL;
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+ return a0ns && a1ns && strcmp (a0ns, a1ns) == 0;
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+ }
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+ return false;
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case tcc_exceptional:
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if (TREE_CODE (arg0) == CONSTRUCTOR)
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@@ -3921,14 +3936,14 @@ bool
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operand_compare::verify_hash_value (const_tree arg0, const_tree arg1,
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unsigned int flags, bool *ret)
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{
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- /* When checking, verify at the outermost operand_equal_p call that
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- if operand_equal_p returns non-zero then ARG0 and ARG1 has the same
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- hash value. */
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+ /* When checking and unless comparing DECL names, verify that if
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+ the outermost operand_equal_p call returns non-zero then ARG0
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+ and ARG1 have the same hash value. */
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if (flag_checking && !(flags & OEP_NO_HASH_CHECK))
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{
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if (operand_equal_p (arg0, arg1, flags | OEP_NO_HASH_CHECK))
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{
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- if (arg0 != arg1)
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+ if (arg0 != arg1 && !(flags & OEP_DECL_NAME))
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{
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inchash::hash hstate0 (0), hstate1 (0);
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hash_operand (arg0, hstate0, flags | OEP_HASH_CHECK);
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diff --git a/gcc/testsuite/gcc.dg/Wvla-parameter-12.c b/gcc/testsuite/gcc.dg/Wvla-parameter-12.c
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new file mode 100644
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index 00000000000..1be5e48203b
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--- /dev/null
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+++ b/gcc/testsuite/gcc.dg/Wvla-parameter-12.c
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@@ -0,0 +1,36 @@
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+/* PR c/101289 - bogus -Wvla-parameter warning when using const bound
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+ { dg-do compile }
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+ { dg-options "-Wall" } */
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+
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+void f1ci_can (const int n, char a[n]);
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+void f1ci_can (const int n, char a[n]); // { dg-bogus "-Wvla-parameter" }
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+
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+void f2ci_can (const int m, char a[m]);
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+void f2ci_can (int n, char a[n]); // { dg-bogus "-Wvla-parameter" }
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+
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+void f3i_can (int n, char a[n]);
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+void f3i_can (const int n, char a[n]); // { dg-bogus "-Wvla-parameter" }
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+
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+void f4i_can (int n, char a[n]);
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+void f4i_can (const int n, char a[(int)n]); // { dg-bogus "-Wvla-parameter" }
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+
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+void f5i_can (int n, char a[(char)n]);
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+void f5i_can (const int n, char a[(char)n]); // { dg-bogus "-Wvla-parameter" }
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+
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+void f6i_can (int m, char a[(char)m]);
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+void f6i_can (const int n, char a[(char)n]); // { dg-bogus "-Wvla-parameter" "" { xfail *-*-* } }
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+
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+
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+/* PR c/97548 - bogus -Wvla-parameter on a bound expression involving
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+ a parameter */
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+
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+int n;
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+
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+void f7ianp1 (int, int[n + 1]);
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+void f7ianp1 (int, int[n + 1]);
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+void f7ianp1 (int, int[n + 2]); // { dg-warning "-Wvla-parameter" }
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+
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+void f8iakp1 (int k, int [k + 1]);
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+void f8iakp1 (int k, int [k + 1]); // { dg-bogus "-Wvla-parameter" }
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+void f8iakp1 (int k, int [1 + k]); // { dg-bogus "-Wvla-parameter" }
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+void f8iakp1 (int k, int [k + 2]); // { dg-warning "-Wvla-parameter" }
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diff --git a/gcc/tree-core.h b/gcc/tree-core.h
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index 07ddf91a230..c31b8ebf249 100644
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--- a/gcc/tree-core.h
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+++ b/gcc/tree-core.h
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@@ -885,6 +885,7 @@ enum size_type_kind {
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stk_type_kind_last
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};
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+/* Flags controlling operand_equal_p() behavior. */
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enum operand_equal_flag {
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OEP_ONLY_CONST = 1,
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OEP_PURE_SAME = 2,
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@@ -899,7 +900,11 @@ enum operand_equal_flag {
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OEP_BITWISE = 128,
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/* For OEP_ADDRESS_OF of COMPONENT_REFs, only consider same fields as
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equivalent rather than also different fields with the same offset. */
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- OEP_ADDRESS_OF_SAME_FIELD = 256
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+ OEP_ADDRESS_OF_SAME_FIELD = 256,
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+ /* In conjunction with OEP_LEXICOGRAPHIC considers names of declarations
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+ of the same kind. Used to compare VLA bounds involving parameters
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+ across redeclarations of the same function. */
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+ OEP_DECL_NAME = 512
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};
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/* Enum and arrays used for tree allocation stats.
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--
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2.31.1
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