https://github.com/hardikxk created
https://github.com/llvm/llvm-project/pull/212108
The patch updates the `TryEvaluateBuiltinNan` method to reject non-narrow
string literals preventing the downstream assertion failure caused by
`getString()` in cases where the user might pass a non-narrow / non 1 byte
literal."
I think this requires tests as well but I haven't added them since when I tried
to, I had some issues and the tests seem to keep failing. (I considered asking
on discord before pushing this patch but I supposed this would be a better
place instead).
I'm sharing the patch I tried for the tests. If I can get some feedback on how
to correctly write them I will push the changes in the following commit if
these tests are required.
```bash
diff --git a/clang/test/Sema/constexpr.c b/clang/test/Sema/constexpr.c
index 51ee62d249..843099e66e 100644
--- a/clang/test/Sema/constexpr.c
+++ b/clang/test/Sema/constexpr.c
@@ -343,6 +343,10 @@ void f7(int n, int array[n]) {
#define FLT_NAN __builtin_nanf("1")
#define DBL_NAN __builtin_nan("1")
#define LD_NAN __builtin_nanf("1")
+#define WIDE_NAN __builtin_nanf(L"1")
+#define UTF32_NAN __builtin_nanf(U"1")
+#define UTF16_NAN __builtin_nanf(u"1")
+#define UTF8_NAN __builtin_nanf(u8"1")
#define FLT_SNAN __builtin_nansf("1")
#define DBL_SNAN __builtin_nans("1")
#define LD_SNAN __builtin_nansl("1")
@@ -357,6 +361,14 @@ void infsNaNs() {
constexpr float fl6 = LD_NAN;
constexpr float fl7 = DBL_SNAN; // expected-error {{constexpr initializer
evaluates to nan which is not exactly representable in type 'const float'}}
constexpr float fl8 = LD_SNAN; // expected-error {{constexpr initializer
evaluates to nan which is not exactly representable in type 'const float'}}
+ constexpr float fl9 = WIDE_NAN; // expected-error {{incompatible pointer
types passing 'int[2]' to parameter of type 'const char *'}} \
+ // expected-error {{constexpr variable 'fl9'
mustbe initialized by a constant expression}}
+ constexpr float fl10 = UTF32_NAN; // expected-error {{incompatible pointer
types passing 'unsigned int[2]' to parameter of type 'const char *'}} \
+ // expected-error {{constexpr variable
'fl10' must be initialized by a constant expression}}
+ constexpr float fl11 = UTF16_NAN; // expected-error {{incompatible pointer
types passing 'unsigned short[2]' to parameter of type 'const char *'}} \
+ // expected-error {{constexpr variable
'fl11' must be initialized by a constant expression}}
+ constexpr float fl12 = UTF8_NAN; // expected-warning {{passing 'unsigned
char[2]' to parameter of type 'const char *' converts between pointers to
integer types whereone is of the unique plain 'char' type and the other is
not}} \
+ // expected-error {{constexpr variable
'fl12' must be initialized by a constant expression}}
constexpr double db0 = FLT_NAN;
constexpr double db2 = DBL_NAN;
```
related issue: #205306
>From aa63ae0b8eba336923a970b4c4b415e1c4424ec6 Mon Sep 17 00:00:00 2001
From: Hardik Kumar <[email protected]>
Date: Sun, 26 Jul 2026 15:58:04 +0530
Subject: [PATCH] [clang]Fix the StringRef assertion failure for non-narrow
strings. The patch updates the method to reject non-narrow string literals
preventing the downstream assertion failure caused by in cases where the
user might pass a non-narrow / non 1 byte literal.
---
clang/lib/AST/ExprConstant.cpp | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index 574dd8b04e779..a3385d3b7318f 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -20394,7 +20394,8 @@ static bool TryEvaluateBuiltinNaN(const ASTContext
&Context,
bool SNaN,
llvm::APFloat &Result) {
const StringLiteral *S = dyn_cast<StringLiteral>(Arg->IgnoreParenCasts());
- if (!S) return false;
+ if (!S || !S->isOrdinary())
+ return false;
const llvm::fltSemantics &Sem = Context.getFloatTypeSemantics(ResultTy);
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