[flang] Fix -Wcharacter-conversion warnings (NFC) #155873
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@llvm/pr-subscribers-flang-parser @llvm/pr-subscribers-flang-semantics Author: Nikita Popov (nikic) ChangesThis fixes new warnings when building with Clang 21, encountered in #155627. Full diff: https://github.com/llvm/llvm-project/pull/155873.diff 2 Files Affected:
diff --git a/flang/lib/Evaluate/fold-implementation.h b/flang/lib/Evaluate/fold-implementation.h
index d757ef6e62eb4..3fdf3a6f38848 100644
--- a/flang/lib/Evaluate/fold-implementation.h
+++ b/flang/lib/Evaluate/fold-implementation.h
@@ -1785,7 +1785,7 @@ common::IfNoLvalue<std::optional<TO>, FROM> ConvertString(FROM &&s) {
if (static_cast<std::uint64_t>(*iter) > 127) {
return std::nullopt;
}
- str.push_back(*iter);
+ str.push_back(static_cast<typename TO::value_type>(*iter));
}
return std::make_optional<TO>(std::move(str));
}
diff --git a/flang/lib/Parser/characters.cpp b/flang/lib/Parser/characters.cpp
index f6ac777ea874c..1a00b16eefe9d 100644
--- a/flang/lib/Parser/characters.cpp
+++ b/flang/lib/Parser/characters.cpp
@@ -289,7 +289,8 @@ RESULT DecodeString(const std::string &s, bool backslashEscapes) {
DecodeCharacter<ENCODING>(p, bytes, backslashEscapes)};
if (decoded.bytes > 0) {
if (static_cast<std::size_t>(decoded.bytes) <= bytes) {
- result.append(1, decoded.codepoint);
+ result.append(
+ 1, static_cast<typename RESULT::value_type>(decoded.codepoint));
bytes -= decoded.bytes;
p += decoded.bytes;
continue;
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| @@ -1785,7 +1785,7 @@ common::IfNoLvalue<std::optional<TO>, FROM> ConvertString(FROM &&s) { | |||
| if (static_cast<std::uint64_t>(*iter) > 127) { | |||
| return std::nullopt; | |||
| } | |||
| str.push_back(*iter); | |||
| str.push_back(static_cast<typename TO::value_type>(*iter)); | |||
There was a problem hiding this comment.
This one is safe due to the preceding check.
| @@ -289,7 +289,8 @@ RESULT DecodeString(const std::string &s, bool backslashEscapes) { | |||
| DecodeCharacter<ENCODING>(p, bytes, backslashEscapes)}; | |||
| if (decoded.bytes > 0) { | |||
| if (static_cast<std::size_t>(decoded.bytes) <= bytes) { | |||
| result.append(1, decoded.codepoint); | |||
| result.append( | |||
| 1, static_cast<typename RESULT::value_type>(decoded.codepoint)); | |||
There was a problem hiding this comment.
This one looks like it might truncate. Don't know whether this is somehow excluded by the broader context.
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There is the overload std::u16string DecodeString<std::u16string, Encoding::UTF_8>. A character outside the unicode basic plane needs more than 16 bits.
According to https://flang.llvm.org/docs/Character.html#kinds-and-character-sets, Fortran strings are expected to be UCS-2 and truncation is expected.
In particular, conversions between kinds are assumed to be simple zero-extensions or truncation, not table look-ups.
| @@ -289,7 +289,8 @@ RESULT DecodeString(const std::string &s, bool backslashEscapes) { | |||
| DecodeCharacter<ENCODING>(p, bytes, backslashEscapes)}; | |||
| if (decoded.bytes > 0) { | |||
| if (static_cast<std::size_t>(decoded.bytes) <= bytes) { | |||
| result.append(1, decoded.codepoint); | |||
| result.append( | |||
| 1, static_cast<typename RESULT::value_type>(decoded.codepoint)); | |||
There was a problem hiding this comment.
There is the overload std::u16string DecodeString<std::u16string, Encoding::UTF_8>. A character outside the unicode basic plane needs more than 16 bits.
According to https://flang.llvm.org/docs/Character.html#kinds-and-character-sets, Fortran strings are expected to be UCS-2 and truncation is expected.
In particular, conversions between kinds are assumed to be simple zero-extensions or truncation, not table look-ups.
This fixes new warnings when building with Clang 21, encountered in #155627.