https://github.com/wheatman updated
https://github.com/llvm/llvm-project/pull/69061
>From 44e66636bd886b263a15fe9e49d575d8ea53592d Mon Sep 17 00:00:00 2001
From: Brian Wheatman <bwheat...@gmail.com>
Date: Sat, 14 Oct 2023 12:02:19 -0400
Subject: [PATCH] Remove warnings from -Wchar-subscripts for known positive
constants
---
clang/lib/Sema/SemaExpr.cpp | 12 ++-
clang/test/Sema/warn-char-subscripts.c | 25 ++++++
clang/test/Sema/warn-char-subscripts.cpp | 103 +++++++++++++++++++++++
3 files changed, 137 insertions(+), 3 deletions(-)
create mode 100644 clang/test/Sema/warn-char-subscripts.cpp
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index aa30a3a03887558..dd9ba5cecaf2404 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -6018,9 +6018,15 @@ Sema::CreateBuiltinArraySubscriptExpr(Expr *Base,
SourceLocation LLoc,
<< IndexExpr->getSourceRange());
if ((IndexExpr->getType()->isSpecificBuiltinType(BuiltinType::Char_S) ||
- IndexExpr->getType()->isSpecificBuiltinType(BuiltinType::Char_U))
- && !IndexExpr->isTypeDependent())
- Diag(LLoc, diag::warn_subscript_is_char) << IndexExpr->getSourceRange();
+ IndexExpr->getType()->isSpecificBuiltinType(BuiltinType::Char_U)) &&
+ !IndexExpr->isTypeDependent()) {
+ std::optional<llvm::APSInt> IntegerContantExpr =
+ IndexExpr->getIntegerConstantExpr(getASTContext());
+ if (!(IntegerContantExpr.has_value() &&
+ IntegerContantExpr.value().isNonNegative())) {
+ Diag(LLoc, diag::warn_subscript_is_char) << IndexExpr->getSourceRange();
+ }
+ }
// C99 6.5.2.1p1: "shall have type "pointer to *object* type". Similarly,
// C++ [expr.sub]p1: The type "T" shall be a completely-defined object
diff --git a/clang/test/Sema/warn-char-subscripts.c
b/clang/test/Sema/warn-char-subscripts.c
index 2e72d90fa612aed..61409c0a50daf47 100644
--- a/clang/test/Sema/warn-char-subscripts.c
+++ b/clang/test/Sema/warn-char-subscripts.c
@@ -62,3 +62,28 @@ void t10(void) {
UnsignedCharTy subscript = 0;
int val = array[subscript]; // no warning for unsigned char
}
+
+void t11(void) {
+ int array[256] = { 0 };
+ int val = array['a']; // no warning for char with known positive value
+}
+
+void t12(void) {
+ int array[256] = { 0 };
+ char b = 'a';
+ int val = array[b]; // expected-warning{{array subscript is of type 'char'}}
+}
+
+void t13(void) {
+ int array[256] = { 0 };
+ const char b = 'a';
+ int val = array[b]; // expected-warning{{array subscript is of type 'char'}}
+}
+
+void t14(void) {
+ int array[256] = { 0 }; // expected-note {{array 'array' declared here}}
+ const char b = -1;
+ // expected-warning@+2 {{array subscript is of type 'char'}}
+ // expected-warning@+1 {{array index -1 is before the beginning of the
array}}
+ int val = array[b];
+}
\ No newline at end of file
diff --git a/clang/test/Sema/warn-char-subscripts.cpp
b/clang/test/Sema/warn-char-subscripts.cpp
new file mode 100644
index 000000000000000..21b991d83590937
--- /dev/null
+++ b/clang/test/Sema/warn-char-subscripts.cpp
@@ -0,0 +1,103 @@
+// RUN: %clang_cc1 -Wchar-subscripts -fsyntax-only -verify %s
+
+void t1(void) {
+ int array[1] = { 0 };
+ char subscript = 0;
+ int val = array[subscript]; // expected-warning{{array subscript is of type
'char'}}
+}
+
+void t2(void) {
+ int array[1] = { 0 };
+ char subscript = 0;
+ int val = subscript[array]; // expected-warning{{array subscript is of type
'char'}}
+}
+
+void t3(void) {
+ int *array = 0;
+ char subscript = 0;
+ int val = array[subscript]; // expected-warning{{array subscript is of type
'char'}}
+}
+
+void t4(void) {
+ int *array = 0;
+ char subscript = 0;
+ int val = subscript[array]; // expected-warning{{array subscript is of type
'char'}}
+}
+
+char returnsChar(void);
+void t5(void) {
+ int *array = 0;
+ int val = array[returnsChar()]; // expected-warning{{array subscript is of
type 'char'}}
+}
+
+void t6(void) {
+ int array[1] = { 0 };
+ signed char subscript = 0;
+ int val = array[subscript]; // no warning for explicit signed char
+}
+
+void t7(void) {
+ int array[1] = { 0 };
+ unsigned char subscript = 0;
+ int val = array[subscript]; // no warning for unsigned char
+}
+
+typedef char CharTy;
+void t8(void) {
+ int array[1] = { 0 };
+ CharTy subscript = 0;
+ int val = array[subscript]; // expected-warning{{array subscript is of type
'char'}}
+}
+
+typedef signed char SignedCharTy;
+void t9(void) {
+ int array[1] = { 0 };
+ SignedCharTy subscript = 0;
+ int val = array[subscript]; // no warning for explicit signed char
+}
+
+typedef unsigned char UnsignedCharTy;
+void t10(void) {
+ int array[1] = { 0 };
+ UnsignedCharTy subscript = 0;
+ int val = array[subscript]; // no warning for unsigned char
+}
+
+void t11(void) {
+ int array[256] = { 0 };
+ int val = array['a']; // no warning for char with known positive value
+}
+
+void t12(void) {
+ int array[256] = { 0 };
+ char b = 'a';
+ int val = array[b]; // expected-warning{{array subscript is of type 'char'}}
+}
+
+void t13(void) {
+ int array[256] = { 0 };
+ const char b = 'a';
+ int val = array[b]; // no warning for char with known positive value
+}
+
+void t14(void) {
+ int array[256] = { 0 };
+ constexpr char b = 'a';
+ int val = array[b]; // no warning for char with known positive value
+}
+
+void t15(void) {
+ int array[256] = { 0 }; // expected-note {{array 'array' declared here}}
+ const char b = -1;
+ // expected-warning@+2 {{array subscript is of type 'char'}}
+ // expected-warning@+1 {{array index -1 is before the beginning of the
array}}
+ int val = array[b];
+}
+
+void t16(void) {
+ int array[256] = { 0 }; // expected-note {{array 'array' declared here}}
+ constexpr char b = -1;
+ // expected-warning@+2 {{array subscript is of type 'char'}}
+ // expected-warning@+1 {{array index -1 is before the beginning of the
array}}
+ int val = array[b];
+}
\ No newline at end of file
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