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      1 //===--- Warnings.cpp - C-Language Front-end ------------------------------===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 //
     10 // Command line warning options handler.
     11 //
     12 //===----------------------------------------------------------------------===//
     13 //
     14 // This file is responsible for handling all warning options. This includes
     15 // a number of -Wfoo options and their variants, which are driven by TableGen-
     16 // generated data, and the special cases -pedantic, -pedantic-errors, -w,
     17 // -Werror and -Wfatal-errors.
     18 //
     19 // Each warning option controls any number of actual warnings.
     20 // Given a warning option 'foo', the following are valid:
     21 //    -Wfoo, -Wno-foo, -Werror=foo, -Wfatal-errors=foo
     22 //
     23 #include "clang/Frontend/Utils.h"
     24 #include "clang/Basic/Diagnostic.h"
     25 #include "clang/Basic/DiagnosticOptions.h"
     26 #include "clang/Frontend/FrontendDiagnostic.h"
     27 #include "clang/Lex/LexDiagnostic.h"
     28 #include "clang/Sema/SemaDiagnostic.h"
     29 #include <algorithm>
     30 #include <cstring>
     31 #include <utility>
     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                                   StringRef Prefix, StringRef Opt,
     38                                   bool isPositive) {
     39   StringRef Suggestion = DiagnosticIDs::getNearestWarningOption(Opt);
     40   if (!Suggestion.empty())
     41     Diags.Report(isPositive? diag::warn_unknown_warning_option_suggest :
     42                              diag::warn_unknown_negative_warning_option_suggest)
     43       << (Prefix.str() += Opt) << (Prefix.str() += Suggestion);
     44   else
     45     Diags.Report(isPositive? diag::warn_unknown_warning_option :
     46                              diag::warn_unknown_negative_warning_option)
     47       << (Prefix.str() += Opt);
     48 }
     49 
     50 void clang::ProcessWarningOptions(DiagnosticsEngine &Diags,
     51                                   const DiagnosticOptions &Opts,
     52                                   bool ReportDiags) {
     53   Diags.setSuppressSystemWarnings(true);  // Default to -Wno-system-headers
     54   Diags.setIgnoreAllWarnings(Opts.IgnoreWarnings);
     55   Diags.setShowOverloads(Opts.getShowOverloads());
     56 
     57   Diags.setElideType(Opts.ElideType);
     58   Diags.setPrintTemplateTree(Opts.ShowTemplateTree);
     59   Diags.setWarnOnSpellCheck(Opts.WarnOnSpellCheck);
     60   Diags.setShowColors(Opts.ShowColors);
     61 
     62   // Handle -ferror-limit
     63   if (Opts.ErrorLimit)
     64     Diags.setErrorLimit(Opts.ErrorLimit);
     65   if (Opts.TemplateBacktraceLimit)
     66     Diags.setTemplateBacktraceLimit(Opts.TemplateBacktraceLimit);
     67   if (Opts.ConstexprBacktraceLimit)
     68     Diags.setConstexprBacktraceLimit(Opts.ConstexprBacktraceLimit);
     69 
     70   // If -pedantic or -pedantic-errors was specified, then we want to map all
     71   // extension diagnostics onto WARNING or ERROR unless the user has futz'd
     72   // around with them explicitly.
     73   if (Opts.PedanticErrors)
     74     Diags.setExtensionHandlingBehavior(DiagnosticsEngine::Ext_Error);
     75   else if (Opts.Pedantic)
     76     Diags.setExtensionHandlingBehavior(DiagnosticsEngine::Ext_Warn);
     77   else
     78     Diags.setExtensionHandlingBehavior(DiagnosticsEngine::Ext_Ignore);
     79 
     80   SmallVector<diag::kind, 10> _Diags;
     81   const IntrusiveRefCntPtr< DiagnosticIDs > DiagIDs =
     82     Diags.getDiagnosticIDs();
     83   // We parse the warning options twice.  The first pass sets diagnostic state,
     84   // while the second pass reports warnings/errors.  This has the effect that
     85   // we follow the more canonical "last option wins" paradigm when there are
     86   // conflicting options.
     87   for (unsigned Report = 0, ReportEnd = 2; Report != ReportEnd; ++Report) {
     88     bool SetDiagnostic = (Report == 0);
     89 
     90     // If we've set the diagnostic state and are not reporting diagnostics then
     91     // we're done.
     92     if (!SetDiagnostic && !ReportDiags)
     93       break;
     94 
     95     for (unsigned i = 0, e = Opts.Warnings.size(); i != e; ++i) {
     96       StringRef Opt = Opts.Warnings[i];
     97       StringRef OrigOpt = Opts.Warnings[i];
     98 
     99       // Treat -Wformat=0 as an alias for -Wno-format.
    100       if (Opt == "format=0")
    101         Opt = "no-format";
    102 
    103       // Check to see if this warning starts with "no-", if so, this is a
    104       // negative form of the option.
    105       bool isPositive = true;
    106       if (Opt.startswith("no-")) {
    107         isPositive = false;
    108         Opt = Opt.substr(3);
    109       }
    110 
    111       // Figure out how this option affects the warning.  If -Wfoo, map the
    112       // diagnostic to a warning, if -Wno-foo, map it to ignore.
    113       diag::Mapping Mapping = isPositive ? diag::MAP_WARNING : diag::MAP_IGNORE;
    114 
    115       // -Wsystem-headers is a special case, not driven by the option table.  It
    116       // cannot be controlled with -Werror.
    117       if (Opt == "system-headers") {
    118         if (SetDiagnostic)
    119           Diags.setSuppressSystemWarnings(!isPositive);
    120         continue;
    121       }
    122 
    123       // -Weverything is a special case as well.  It implicitly enables all
    124       // warnings, including ones not explicitly in a warning group.
    125       if (Opt == "everything") {
    126         if (SetDiagnostic) {
    127           if (isPositive) {
    128             Diags.setEnableAllWarnings(true);
    129           } else {
    130             Diags.setEnableAllWarnings(false);
    131             Diags.setMappingToAllDiagnostics(diag::MAP_IGNORE);
    132           }
    133         }
    134         continue;
    135       }
    136 
    137       // -Werror/-Wno-error is a special case, not controlled by the option
    138       // table. It also has the "specifier" form of -Werror=foo and -Werror-foo.
    139       if (Opt.startswith("error")) {
    140         StringRef Specifier;
    141         if (Opt.size() > 5) {  // Specifier must be present.
    142           if ((Opt[5] != '=' && Opt[5] != '-') || Opt.size() == 6) {
    143             if (Report)
    144               Diags.Report(diag::warn_unknown_warning_specifier)
    145                 << "-Werror" << ("-W" + OrigOpt.str());
    146             continue;
    147           }
    148           Specifier = Opt.substr(6);
    149         }
    150 
    151         if (Specifier.empty()) {
    152           if (SetDiagnostic)
    153             Diags.setWarningsAsErrors(isPositive);
    154           continue;
    155         }
    156 
    157         if (SetDiagnostic) {
    158           // Set the warning as error flag for this specifier.
    159           Diags.setDiagnosticGroupWarningAsError(Specifier, isPositive);
    160         } else if (DiagIDs->getDiagnosticsInGroup(Specifier, _Diags)) {
    161           EmitUnknownDiagWarning(Diags, "-Werror=", Specifier, isPositive);
    162         }
    163         continue;
    164       }
    165 
    166       // -Wfatal-errors is yet another special case.
    167       if (Opt.startswith("fatal-errors")) {
    168         StringRef Specifier;
    169         if (Opt.size() != 12) {
    170           if ((Opt[12] != '=' && Opt[12] != '-') || Opt.size() == 13) {
    171             if (Report)
    172               Diags.Report(diag::warn_unknown_warning_specifier)
    173                 << "-Wfatal-errors" << ("-W" + OrigOpt.str());
    174             continue;
    175           }
    176           Specifier = Opt.substr(13);
    177         }
    178 
    179         if (Specifier.empty()) {
    180           if (SetDiagnostic)
    181             Diags.setErrorsAsFatal(isPositive);
    182           continue;
    183         }
    184 
    185         if (SetDiagnostic) {
    186           // Set the error as fatal flag for this specifier.
    187           Diags.setDiagnosticGroupErrorAsFatal(Specifier, isPositive);
    188         } else if (DiagIDs->getDiagnosticsInGroup(Specifier, _Diags)) {
    189           EmitUnknownDiagWarning(Diags, "-Wfatal-errors=", Specifier,
    190                                  isPositive);
    191         }
    192         continue;
    193       }
    194 
    195       if (Report) {
    196         if (DiagIDs->getDiagnosticsInGroup(Opt, _Diags))
    197           EmitUnknownDiagWarning(Diags, isPositive ? "-W" : "-Wno-", Opt,
    198                                  isPositive);
    199       } else {
    200         Diags.setDiagnosticGroupMapping(Opt, Mapping);
    201       }
    202     }
    203   }
    204 }
    205