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