Author: alexpaniman Date: 2026-04-03T08:33:36-04:00 New Revision: b9924c76da9126cdf1e4345cbb6b061c65c920db
URL: https://github.com/llvm/llvm-project/commit/b9924c76da9126cdf1e4345cbb6b061c65c920db DIFF: https://github.com/llvm/llvm-project/commit/b9924c76da9126cdf1e4345cbb6b061c65c920db.diff LOG: [clang] Make -dump-tokens option align tokens (#164894) When using `-Xclang -dump-tokens`, the lexer dump output is currently difficult to read because the data are misaligned. The existing implementation simply separates the token name, spelling, flags, and location using `'\t'`, which results in inconsistent spacing. For example, the current output looks like this on provided in this patch example **(BEFORE THIS PR)**: <img width="2936" height="632" alt="image" src="https://github.com/user-attachments/assets/ad893958-6d57-4a76-8838-7fc56e37e6a7"; /> # Changes This small PR improves the readability of the token dump by: + Adding padding after the token name and after the spelling (the padding amount was chosen empirically to produce good average alignment). + Swapping the order of location and flags (since flags can take up a lot of space and disrupt alignment). The result is a more readable output **(AFTER THIS PR)**: <img width="1470" height="315" alt="image" src="https://github.com/user-attachments/assets/c24f24e5-a431-42cc-b5b6-232bac5c635e"; /> Added: clang/test/Preprocessor/dump-tokens.cpp Modified: clang/lib/Lex/Preprocessor.cpp Removed: ################################################################################ diff --git a/clang/lib/Lex/Preprocessor.cpp b/clang/lib/Lex/Preprocessor.cpp index 2cfefac1052a4..c430da67c1469 100644 --- a/clang/lib/Lex/Preprocessor.cpp +++ b/clang/lib/Lex/Preprocessor.cpp @@ -61,6 +61,7 @@ #include "llvm/ADT/StringRef.h" #include "llvm/Support/Capacity.h" #include "llvm/Support/ErrorHandling.h" +#include "llvm/Support/FormatVariadic.h" #include "llvm/Support/MemoryBuffer.h" #include "llvm/Support/MemoryBufferRef.h" #include "llvm/Support/SaveAndRestore.h" @@ -240,14 +241,59 @@ void Preprocessor::FinalizeForModelFile() { } void Preprocessor::DumpToken(const Token &Tok, bool DumpFlags) const { - llvm::errs() << tok::getTokenName(Tok.getKind()); + std::string TokenStr; + llvm::raw_string_ostream OS(TokenStr); + + // The alignment of 16 is chosen to comfortably fit most identifiers. + OS << llvm::formatv("{0,-16} ", tok::getTokenName(Tok.getKind())); + + // Annotation tokens are just markers that don't have a spelling -- they + // indicate where something expanded. + if (!Tok.isAnnotation()) { + OS << "'"; + // Escape string to prevent token spelling from spanning multiple lines. + OS.write_escaped(getSpelling(Tok)); + OS << "'"; + } - if (!Tok.isAnnotation()) - llvm::errs() << " '" << getSpelling(Tok) << "'"; + // The alignment of 48 (32 characters for the spelling + the 16 for + // the identifier name) fits most variable names, keywords and annotations. + llvm::errs() << llvm::formatv("{0,-48} ", OS.str()); if (!DumpFlags) return; - llvm::errs() << "\t"; + auto Loc = Tok.getLocation(); + llvm::errs() << "Loc=<"; + DumpLocation(Loc); + llvm::errs() << ">"; + + // If the token points directly to a file location (i.e. not a macro + // expansion), then add additional padding so that trailing markers + // align, provided the line/column numbers are reasonably sized. + // + // Otherwise, if it's a macro expansion, don't bother with alignment, + // as the line will include multiple locations and be very long. + // + // NOTE: To keep this stateless, it doesn't account for filename + // length, so when a header starts markers will be temporarily misaligned. + if (Loc.isFileID()) { + PresumedLoc PLoc = SourceMgr.getPresumedLoc(Loc); + + if (!PLoc.isInvalid()) { + int LineWidth = llvm::utostr(PLoc.getLine()).size(); + int ColumnWidth = llvm::utostr(PLoc.getColumn()).size(); + + // Reserve space for lines up to 9999 and columns up to 99, + // which is 4 + 2 = 6 characters in total. + const int ReservedSpace = 6; + + int LeftSpace = ReservedSpace - LineWidth - ColumnWidth; + int Padding = std::max<int>(0, LeftSpace); + + llvm::errs().indent(Padding); + } + } + if (Tok.isAtStartOfLine()) llvm::errs() << " [StartOfLine]"; if (Tok.hasLeadingSpace()) @@ -256,13 +302,8 @@ void Preprocessor::DumpToken(const Token &Tok, bool DumpFlags) const { llvm::errs() << " [ExpandDisabled]"; if (Tok.needsCleaning()) { const char *Start = SourceMgr.getCharacterData(Tok.getLocation()); - llvm::errs() << " [UnClean='" << StringRef(Start, Tok.getLength()) - << "']"; + llvm::errs() << " [UnClean='" << StringRef(Start, Tok.getLength()) << "']"; } - - llvm::errs() << "\tLoc=<"; - DumpLocation(Tok.getLocation()); - llvm::errs() << ">"; } void Preprocessor::DumpLocation(SourceLocation Loc) const { diff --git a/clang/test/Preprocessor/dump-tokens.cpp b/clang/test/Preprocessor/dump-tokens.cpp new file mode 100644 index 0000000000000..315548530d4df --- /dev/null +++ b/clang/test/Preprocessor/dump-tokens.cpp @@ -0,0 +1,37 @@ +// RUN: %clang_cc1 -dump-tokens %s 2>&1 | FileCheck %s --strict-whitespace + +// To make location reporting in the test more robust, provide line number and file name explicitly. +#line 2 "dump-tokens.cpp" + +// Different kinds of identifiers with diff erent spelling lengths. +-> // CHECK: arrow '->' Loc=<{{.*}}:4:1> [StartOfLine] +5 // CHECK-NEXT: numeric_constant '5' Loc=<{{.*}}:5:1> [StartOfLine] +id // CHECK-NEXT: identifier 'id' Loc=<{{.*}}:6:1> [StartOfLine] +& // CHECK-NEXT: amp '&' Loc=<{{.*}}:7:1> [StartOfLine] +) // CHECK-NEXT: r_paren ')' Loc=<{{.*}}:8:1> [StartOfLine] +unsigned // CHECK-NEXT: unsigned 'unsigned' Loc=<{{.*}}:9:1> [StartOfLine] +~ // CHECK-NEXT: tilde '~' Loc=<{{.*}}:10:1> [StartOfLine] +long_variable_name_very_long // CHECK-NEXT: identifier 'long_variable_name_very_long' Loc=<{{.*}}:11:1> [StartOfLine] +union // CHECK-NEXT: union 'union' Loc=<{{.*}}:12:1> [StartOfLine] +42 // CHECK-NEXT: numeric_constant '42' Loc=<{{.*}}:13:1> [StartOfLine] +j // CHECK-NEXT: identifier 'j' Loc=<{{.*}}:14:1> [StartOfLine] +&= // CHECK-NEXT: ampequal '&=' Loc=<{{.*}}:15:1> [StartOfLine] +15 // CHECK-NEXT: numeric_constant '15' Loc=<{{.*}}:16:1> [StartOfLine] + +// Different locations in line and trailing markers. + at diff erent locations= in line // CHECK-NEXT: identifier 'at' Loc=<{{.*}}:19:2> [StartOfLine] [LeadingSpace] + // CHECK-NEXT: identifier ' diff erent' Loc=<{{.*}}:19:5> [LeadingSpace] + // CHECK-NEXT: identifier 'locations' Loc=<{{.*}}:19:15> [LeadingSpace] + // CHECK-NEXT: equal '=' Loc=<{{.*}}:19:24> + // CHECK-NEXT: identifier 'in' Loc=<{{.*}}:19:26> [LeadingSpace] + // CHECK-NEXT: identifier 'line' Loc=<{{.*}}:19:29> [LeadingSpace] + +// Tokens that require escaping & annotations. +#pragma clang __debug parser_crash // CHECK-NEXT: annot_pragma_parser_crash Loc=<{{.*}}:27:23> + // CHECK-NEXT: eod '\n' Loc=<{{.*}}:27:119> [LeadingSpace] +#pragma clang __debug captured // CHECK-NEXT: annot_pragma_captured Loc=<{{.*}}:29:120> +#pragma clang __debug dump X // CHECK-NEXT: annot_pragma_dump Loc=<{{.*}}:30:23> + // CHECK-NEXT: identifier 'X' Loc=<{{.*}}:30:28> [LeadingSpace] + // CHECK-NEXT: eod '\n' Loc=<{{.*}}:30:119> [LeadingSpace] + // CHECK-NEXT: eof '' Loc=<{{.*}}:34:1> + _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
