https://github.com/eisenwave created https://github.com/llvm/llvm-project/pull/206326
1. Fix typo in `note_invalid_ucn_name_loose_matching` message. 2. Fix unprintable characters appearing in diagnostic messages. 3. Stop offering low-value fix suggestions when illegal characters appear in the name. >From e2a20d710a1de9b67bcefe162ec3034249722c35 Mon Sep 17 00:00:00 2001 From: Eisenwave <[email protected]> Date: Sun, 28 Jun 2026 14:08:36 +0200 Subject: [PATCH] [clang] Improve diagnostics for invalid named-universal-characters 1. Fix typo in note_invalid_ucn_name_loose_matching message. 2. Fix unprintable characterss appearing in diagnostic messages. 3. Stop offering low-value fix suggestions when illegal characters appear in the name. --- .../include/clang/Basic/DiagnosticLexKinds.td | 6 +- clang/lib/Lex/LiteralSupport.cpp | 60 ++++++++++++++++--- clang/test/CXX/drs/cwg26xx.cpp | 6 +- clang/test/Lexer/char-escapes-delimited.c | 10 +++- clang/test/Lexer/unicode.c | 2 +- clang/test/Preprocessor/ucn-pp-identifier.c | 2 +- 6 files changed, 65 insertions(+), 21 deletions(-) diff --git a/clang/include/clang/Basic/DiagnosticLexKinds.td b/clang/include/clang/Basic/DiagnosticLexKinds.td index 383bf1a7fdb3f..decfd6c781dbf 100644 --- a/clang/include/clang/Basic/DiagnosticLexKinds.td +++ b/clang/include/clang/Basic/DiagnosticLexKinds.td @@ -170,9 +170,11 @@ def err_hex_escape_no_digits : Error< def err_invalid_ucn_name : Error< "'%0' is not a valid Unicode character name">; def note_invalid_ucn_name_loose_matching : Note< - "characters names in Unicode escape sequences are sensitive to case and whitespaces">; + "character names in Unicode escape sequences are sensitive to case and whitespaces">; def note_invalid_ucn_name_candidate : Note< - "did you mean %0 ('%2' U+%1)?">; + "did you mean %0 (%1)?">; +def note_invalid_ucn_name_character : Note< + "character %0 cannot appear in a Unicode character name">; def warn_ucn_escape_no_digits : Warning< "\\%0 used with no following hex digits; " diff --git a/clang/lib/Lex/LiteralSupport.cpp b/clang/lib/Lex/LiteralSupport.cpp index 482146ccf8654..e941e5eecbe8a 100644 --- a/clang/lib/Lex/LiteralSupport.cpp +++ b/clang/lib/Lex/LiteralSupport.cpp @@ -539,6 +539,12 @@ static bool ProcessNumericUCNEscape(const char *ThisTokBegin, return !HasError; } +static bool AllowedInCharacterName(llvm::UTF32 CodePoint) { + return (CodePoint >= U'A' && CodePoint <= U'Z') || + (CodePoint >= U'0' && CodePoint <= U'9') || CodePoint == U'-' || + CodePoint == U' '; +} + static void DiagnoseInvalidUnicodeCharacterName( DiagnosticsEngine *Diags, const LangOptions &Features, FullSourceLoc Loc, const char *TokBegin, const char *TokRangeBegin, const char *TokRangeEnd, @@ -550,6 +556,44 @@ static void DiagnoseInvalidUnicodeCharacterName( namespace u = llvm::sys::unicode; + auto StringifyCodePoint = [](llvm::UTF32 CodePoint) -> llvm::SmallString<16> { + llvm::SmallString<16> Result; + if (u::isPrintable(CodePoint)) { + std::string CharUTF8; + llvm::convertUTF32ToUTF8String(llvm::ArrayRef<llvm::UTF32>(&CodePoint, 1), + CharUTF8); + Result.append("'"); + Result.append(CharUTF8); + Result.append("' U+"); + } else { + Result.append("U+"); + } + llvm::raw_svector_ostream OS(Result); + llvm::write_hex(OS, CodePoint, llvm::HexPrintStyle::Upper, 4); + return Result; + }; + + bool HasIllegalCharacter = false; + for (const char *P = Name.begin(), *E = Name.end(); P != E;) { + const auto *Src = reinterpret_cast<const llvm::UTF8 *>(P); + const auto *SrcEnd = reinterpret_cast<const llvm::UTF8 *>(E); + llvm::UTF32 CodePoint = 0; + if (llvm::convertUTF8Sequence(&Src, SrcEnd, &CodePoint, + llvm::strictConversion) != llvm::conversionOK) + break; + if (AllowedInCharacterName(CodePoint)) { + P = reinterpret_cast<const char *>(Src); + continue; + } + SourceLocation CharLoc = Lexer::AdvanceToTokenCharacter( + Loc, (TokRangeBegin - TokBegin) + (P - Name.begin()), Loc.getManager(), + Features); + Diags->Report(CharLoc, diag::note_invalid_ucn_name_character) + << StringifyCodePoint(CodePoint); + HasIllegalCharacter = true; + break; + } + std::optional<u::LooseMatchingResult> Res = u::nameToCodepointLooseMatching(Name); if (Res) { @@ -562,6 +606,12 @@ static void DiagnoseInvalidUnicodeCharacterName( return; } + // Providing illegal characters suggests a fundamental misuse of the feature, + // like providing emoji in \N{}. Offering alternative suggestions is often + // unhelpful in that scenario. + if (HasIllegalCharacter) + return; + unsigned Distance = 0; SmallVector<u::MatchForCodepointName> Matches = u::nearestMatchesForCodepointName(Name, 5); @@ -576,17 +626,9 @@ static void DiagnoseInvalidUnicodeCharacterName( break; Distance = Match.Distance; - std::string Str; - llvm::UTF32 V = Match.Value; - bool Converted = - llvm::convertUTF32ToUTF8String(llvm::ArrayRef<llvm::UTF32>(&V, 1), Str); - (void)Converted; - assert(Converted && "Found a match wich is not a unicode character"); - Diag(Diags, Features, Loc, TokBegin, TokRangeBegin, TokRangeEnd, diag::note_invalid_ucn_name_candidate) - << Match.Name << llvm::utohexstr(Match.Value) - << Str // FIXME: Fix the rendering of non printable characters + << Match.Name << StringifyCodePoint(Match.Value) << FixItHint::CreateReplacement( MakeCharSourceRange(Features, Loc, TokBegin, TokRangeBegin, TokRangeEnd), diff --git a/clang/test/CXX/drs/cwg26xx.cpp b/clang/test/CXX/drs/cwg26xx.cpp index 45653743ae574..6a15513879bbd 100644 --- a/clang/test/CXX/drs/cwg26xx.cpp +++ b/clang/test/CXX/drs/cwg26xx.cpp @@ -214,11 +214,7 @@ int \N{Λ} = 0; // expected-error@-2 {{expected unqualified-id}} const char* emoji = "\N{🤡}"; // expected-error@-1 {{'🤡' is not a valid Unicode character name}} -// expected-note@-2 {{did you mean OX ('🐂' U+1F402)?}} -// expected-note@-3 {{did you mean ANT ('🐜' U+1F41C)?}} -// expected-note@-4 {{did you mean ARC ('⌒' U+2312)?}} -// expected-note@-5 {{did you mean AXE ('🪓' U+1FA93)?}} -// expected-note@-6 {{did you mean BAT ('🦇' U+1F987)?}} +// expected-note@-2 {{character '🤡' U+1F921 cannot appear in a Unicode character name}} #define z(x) 0 #define cwg2640_a z( diff --git a/clang/test/Lexer/char-escapes-delimited.c b/clang/test/Lexer/char-escapes-delimited.c index 7a8986bc5f867..1c20456701d75 100644 --- a/clang/test/Lexer/char-escapes-delimited.c +++ b/clang/test/Lexer/char-escapes-delimited.c @@ -82,7 +82,8 @@ void named(void) { char b = '\N{DOLLAR SIGN}'; // ext-warning {{extension}} cxx23-warning {{C++23}} char b_ = '\N{ DOL-LAR _SIGN }'; // expected-error {{' DOL-LAR _SIGN ' is not a valid Unicode character name}} \ - // expected-note {{characters names in Unicode escape sequences are sensitive to case and whitespaces}} + // expected-note {{character names in Unicode escape sequences are sensitive to case and whitespaces}} \ + // expected-note {{character '_' U+005F cannot appear in a Unicode character name}} char c = '\N{NOTATHING}'; // expected-error {{'NOTATHING' is not a valid Unicode character name}} \ // expected-note 5{{did you mean}} @@ -100,9 +101,12 @@ void named(void) { unsigned k = u'\N{LOTUS'; // expected-error {{incomplete universal character name}} const char* emoji = "\N{🤡}"; // expected-error {{'🤡' is not a valid Unicode character name}} \ - // expected-note 5{{did you mean}} + // expected-note {{character '🤡' U+1F921 cannot appear in a Unicode character name}} const char* nested = "\N{\N{SPARKLE}}"; // expected-error {{'\N{SPARKLE' is not a valid Unicode character name}} \ - // expected-note 5{{did you mean}} + // expected-note {{cannot appear in a Unicode character name}} + const char* line_feed = "\N{LINE FEE}"; // expected-error {{'LINE FEE' is not a valid Unicode character name}} \ + // expected-note {{did you mean LINE FEED (U+000A)}} \ + // expected-note 4{{did you mean}} } void separators(void) { diff --git a/clang/test/Lexer/unicode.c b/clang/test/Lexer/unicode.c index e0489e11b9da9..2d1edc77a1550 100644 --- a/clang/test/Lexer/unicode.c +++ b/clang/test/Lexer/unicode.c @@ -49,7 +49,7 @@ extern int \u{16D80}; // CHISOI LETTER A - Added in Unicode 18.0 extern int a\N{TANGSA LETTER GA}; extern int a\N{TANGSALETTERGA}; // expected-error {{'TANGSALETTERGA' is not a valid Unicode character name}} \ // expected-error {{expected ';' after top level declarator}} \ - // expected-note {{characters names in Unicode escape sequences are sensitive to case and whitespace}} + // expected-note {{character names in Unicode escape sequences are sensitive to case and whitespace}} extern int 𝛛; // expected-warning {{mathematical notation character <U+1D6DB> in an identifier is a Clang extension}} extern int ₉; // expected-error {{character <U+2089> not allowed at the start of an identifier}} \\ diff --git a/clang/test/Preprocessor/ucn-pp-identifier.c b/clang/test/Preprocessor/ucn-pp-identifier.c index 5efcfe48f638a..ee008a73eb882 100644 --- a/clang/test/Preprocessor/ucn-pp-identifier.c +++ b/clang/test/Preprocessor/ucn-pp-identifier.c @@ -131,7 +131,7 @@ C 1 // expected-error {{macro name must be an identifier}} #define \NN // expected-warning {{incomplete universal character name; treating as '\' followed by identifier}} expected-error {{macro name must be an identifier}} #define \N{GREEK_SMALL-LETTERALPHA} // expected-error {{'GREEK_SMALL-LETTERALPHA' is not a valid Unicode character name}} \ - // expected-note {{characters names in Unicode escape sequences are sensitive to case and whitespaces}} + // expected-note {{character names in Unicode escape sequences are sensitive to case and whitespaces}} #define \N{🤡} // expected-error {{'🤡' is not a valid Unicode character name}} \ // expected-error {{macro name must be an identifier}} _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
