clang/lib/Basic/Warnings.cpp

   1 //===--- Warnings.cpp - C-Language Front-end ------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // Command line warning options handler.
  10 //
  11 //===----------------------------------------------------------------------===//
  12 //
  13 // This file is responsible for handling all warning options. This includes
  14 // a number of -Wfoo options and their variants, which are driven by TableGen-
  15 // generated data, and the special cases -pedantic, -pedantic-errors, -w,
  16 // -Werror and -Wfatal-errors.
  17 //
  18 // Each warning option controls any number of actual warnings.
  19 // Given a warning option 'foo', the following are valid:
  20 //    -Wfoo, -Wno-foo, -Werror=foo, -Wfatal-errors=foo
  21 //
  22 // Remark options are also handled here, analogously, except that they are much
  23 // simpler because a remark can't be promoted to an error.
  24 #include "clang/Basic/AllDiagnostics.h"
  25 #include "clang/Basic/Diagnostic.h"
  26 #include "clang/Basic/DiagnosticDriver.h"
  27 #include "clang/Basic/DiagnosticIDs.h"
  28 #include "clang/Basic/DiagnosticOptions.h"
  29 #include "llvm/ADT/StringRef.h"
  30 #include "llvm/Support/VirtualFileSystem.h"
  31 #include <cstring>
  32 using namespace clang;
  33
  34 // EmitUnknownDiagWarning - Emit a warning and typo hint for unknown warning
  35 // opts
  36 static void EmitUnknownDiagWarning(DiagnosticsEngine &Diags,
  37                                    diag::Flavor Flavor, StringRef Prefix,
  38                                    StringRef Opt) {
  39   StringRef Suggestion = DiagnosticIDs::getNearestOption(Flavor, Opt);
  40   Diags.Report(diag::warn_unknown_diag_option)
  41       << (Flavor == diag::Flavor::WarningOrError ? 0 : 1)
  42       << (Prefix.str() += std::string(Opt)) << !Suggestion.empty()
  43       << (Prefix.str() += std::string(Suggestion));
  44 }
  45
  46 void clang::ProcessWarningOptions(DiagnosticsEngine &Diags,
  47                                   const DiagnosticOptions &Opts,
  48                                   llvm::vfs::FileSystem &VFS,
  49                                   bool ReportDiags) {
  50   Diags.setSuppressSystemWarnings(true);  // Default to -Wno-system-headers
  51   Diags.setIgnoreAllWarnings(Opts.IgnoreWarnings);
  52   Diags.setShowOverloads(Opts.getShowOverloads());
  53
  54   Diags.setElideType(Opts.ElideType);
  55   Diags.setPrintTemplateTree(Opts.ShowTemplateTree);
  56   Diags.setShowColors(Opts.ShowColors);
  57
  58   // Handle -ferror-limit
  59   if (Opts.ErrorLimit)
  60     Diags.setErrorLimit(Opts.ErrorLimit);
  61   if (Opts.TemplateBacktraceLimit)
  62     Diags.setTemplateBacktraceLimit(Opts.TemplateBacktraceLimit);
  63   if (Opts.ConstexprBacktraceLimit)
  64     Diags.setConstexprBacktraceLimit(Opts.ConstexprBacktraceLimit);
  65
  66   // If -pedantic or -pedantic-errors was specified, then we want to map all
  67   // extension diagnostics onto WARNING or ERROR unless the user has futz'd
  68   // around with them explicitly.
  69   if (Opts.PedanticErrors)
  70     Diags.setExtensionHandlingBehavior(diag::Severity::Error);
  71   else if (Opts.Pedantic)
  72     Diags.setExtensionHandlingBehavior(diag::Severity::Warning);
  73   else
  74     Diags.setExtensionHandlingBehavior(diag::Severity::Ignored);
  75
  76   if (!Opts.DiagnosticSuppressionMappingsFile.empty()) {
  77     if (auto FileContents =
  78             VFS.getBufferForFile(Opts.DiagnosticSuppressionMappingsFile)) {
  79       Diags.setDiagSuppressionMapping(**FileContents);
  80     } else if (ReportDiags) {
  81       Diags.Report(diag::err_drv_no_such_file)
  82           << Opts.DiagnosticSuppressionMappingsFile;
  83     }
  84   }
  85
  86   SmallVector<diag::kind, 10> _Diags;
  87   const IntrusiveRefCntPtr< DiagnosticIDs > DiagIDs =
  88     Diags.getDiagnosticIDs();
  89   // We parse the warning options twice.  The first pass sets diagnostic state,
  90   // while the second pass reports warnings/errors.  This has the effect that
  91   // we follow the more canonical "last option wins" paradigm when there are
  92   // conflicting options.
  93   for (unsigned Report = 0, ReportEnd = 2; Report != ReportEnd; ++Report) {
  94     bool SetDiagnostic = (Report == 0);
  95
  96     // If we've set the diagnostic state and are not reporting diagnostics then
  97     // we're done.
  98     if (!SetDiagnostic && !ReportDiags)
  99       break;
 100
 101     for (unsigned i = 0, e = Opts.Warnings.size(); i != e; ++i) {
 102       const auto Flavor = diag::Flavor::WarningOrError;
 103       StringRef Opt = Opts.Warnings[i];
 104       StringRef OrigOpt = Opts.Warnings[i];
 105
 106       // Treat -Wformat=0 as an alias for -Wno-format.
 107       if (Opt == "format=0")
 108         Opt = "no-format";
 109
 110       // Check to see if this warning starts with "no-", if so, this is a
 111       // negative form of the option.
 112       bool isPositive = !Opt.consume_front("no-");
 113
 114       // Figure out how this option affects the warning.  If -Wfoo, map the
 115       // diagnostic to a warning, if -Wno-foo, map it to ignore.
 116       diag::Severity Mapping =
 117           isPositive ? diag::Severity::Warning : diag::Severity::Ignored;
 118
 119       // -Wsystem-headers is a special case, not driven by the option table.  It
 120       // cannot be controlled with -Werror.
 121       if (Opt == "system-headers") {
 122         if (SetDiagnostic)
 123           Diags.setSuppressSystemWarnings(!isPositive);
 124         continue;
 125       }
 126
 127       // -Weverything is a special case as well.  It implicitly enables all
 128       // warnings, including ones not explicitly in a warning group.
 129       if (Opt == "everything") {
 130         if (SetDiagnostic) {
 131           if (isPositive) {
 132             Diags.setEnableAllWarnings(true);
 133           } else {
 134             Diags.setEnableAllWarnings(false);
 135             Diags.setSeverityForAll(Flavor, diag::Severity::Ignored);
 136           }
 137         }
 138         continue;
 139       }
 140
 141       // -Werror/-Wno-error is a special case, not controlled by the option
 142       // table. It also has the "specifier" form of -Werror=foo. GCC supports
 143       // the deprecated -Werror-implicit-function-declaration which is used by
 144       // a few projects.
 145       if (Opt.starts_with("error")) {
 146         StringRef Specifier;
 147         if (Opt.size() > 5) {  // Specifier must be present.
 148           if (Opt[5] != '=' &&
 149               Opt.substr(5) != "-implicit-function-declaration") {
 150             if (Report)
 151               Diags.Report(diag::warn_unknown_warning_specifier)
 152                 << "-Werror" << ("-W" + OrigOpt.str());
 153             continue;
 154           }
 155           Specifier = Opt.substr(6);
 156         }
 157
 158         if (Specifier.empty()) {
 159           if (SetDiagnostic)
 160             Diags.setWarningsAsErrors(isPositive);
 161           continue;
 162         }
 163
 164         if (SetDiagnostic) {
 165           // Set the warning as error flag for this specifier.
 166           Diags.setDiagnosticGroupWarningAsError(Specifier, isPositive);
 167         } else if (DiagIDs->getDiagnosticsInGroup(Flavor, Specifier, _Diags)) {
 168           EmitUnknownDiagWarning(Diags, Flavor, "-Werror=", Specifier);
 169         }
 170         continue;
 171       }
 172
 173       // -Wfatal-errors is yet another special case.
 174       if (Opt.starts_with("fatal-errors")) {
 175         StringRef Specifier;
 176         if (Opt.size() != 12) {
 177           if ((Opt[12] != '=' && Opt[12] != '-') || Opt.size() == 13) {
 178             if (Report)
 179               Diags.Report(diag::warn_unknown_warning_specifier)
 180                 << "-Wfatal-errors" << ("-W" + OrigOpt.str());
 181             continue;
 182           }
 183           Specifier = Opt.substr(13);
 184         }
 185
 186         if (Specifier.empty()) {
 187           if (SetDiagnostic)
 188             Diags.setErrorsAsFatal(isPositive);
 189           continue;
 190         }
 191
 192         if (SetDiagnostic) {
 193           // Set the error as fatal flag for this specifier.
 194           Diags.setDiagnosticGroupErrorAsFatal(Specifier, isPositive);
 195         } else if (DiagIDs->getDiagnosticsInGroup(Flavor, Specifier, _Diags)) {
 196           EmitUnknownDiagWarning(Diags, Flavor, "-Wfatal-errors=", Specifier);
 197         }
 198         continue;
 199       }
 200
 201       if (Report) {
 202         if (DiagIDs->getDiagnosticsInGroup(Flavor, Opt, _Diags))
 203           EmitUnknownDiagWarning(Diags, Flavor, isPositive ? "-W" : "-Wno-",
 204                                  Opt);
 205       } else {
 206         Diags.setSeverityForGroup(Flavor, Opt, Mapping);
 207       }
 208     }
 209
 210     for (StringRef Opt : Opts.Remarks) {
 211       const auto Flavor = diag::Flavor::Remark;
 212
 213       // Check to see if this warning starts with "no-", if so, this is a
 214       // negative form of the option.
 215       bool IsPositive = !Opt.consume_front("no-");
 216
 217       auto Severity = IsPositive ? diag::Severity::Remark
 218                                  : diag::Severity::Ignored;
 219
 220       // -Reverything sets the state of all remarks. Note that all remarks are
 221       // in remark groups, so we don't need a separate 'all remarks enabled'
 222       // flag.
 223       if (Opt == "everything") {
 224         if (SetDiagnostic)
 225           Diags.setSeverityForAll(Flavor, Severity);
 226         continue;
 227       }
 228
 229       if (Report) {
 230         if (DiagIDs->getDiagnosticsInGroup(Flavor, Opt, _Diags))
 231           EmitUnknownDiagWarning(Diags, Flavor, IsPositive ? "-R" : "-Rno-",
 232                                  Opt);
 233       } else {
 234         Diags.setSeverityForGroup(Flavor, Opt,
 235                                   IsPositive ? diag::Severity::Remark
 236                                              : diag::Severity::Ignored);
 237       }
 238     }
 239   }
 240 }