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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.setShowColors(Opts.ShowColors);
     60 
     61   // Handle -ferror-limit
     62   if (Opts.ErrorLimit)
     63     Diags.setErrorLimit(Opts.ErrorLimit);
     64   if (Opts.TemplateBacktraceLimit)
     65     Diags.setTemplateBacktraceLimit(Opts.TemplateBacktraceLimit);
     66   if (Opts.ConstexprBacktraceLimit)
     67     Diags.setConstexprBacktraceLimit(Opts.ConstexprBacktraceLimit);
     68 
     69   // If -pedantic or -pedantic-errors was specified, then we want to map all
     70   // extension diagnostics onto WARNING or ERROR unless the user has futz'd
     71   // around with them explicitly.
     72   if (Opts.PedanticErrors)
     73     Diags.setExtensionHandlingBehavior(DiagnosticsEngine::Ext_Error);
     74   else if (Opts.Pedantic)
     75     Diags.setExtensionHandlingBehavior(DiagnosticsEngine::Ext_Warn);
     76   else
     77     Diags.setExtensionHandlingBehavior(DiagnosticsEngine::Ext_Ignore);
     78 
     79   SmallVector<diag::kind, 10> _Diags;
     80   const IntrusiveRefCntPtr< DiagnosticIDs > DiagIDs =
     81     Diags.getDiagnosticIDs();
     82   // We parse the warning options twice.  The first pass sets diagnostic state,
     83   // while the second pass reports warnings/errors.  This has the effect that
     84   // we follow the more canonical "last option wins" paradigm when there are
     85   // conflicting options.
     86   for (unsigned Report = 0, ReportEnd = 2; Report != ReportEnd; ++Report) {
     87     bool SetDiagnostic = (Report == 0);
     88 
     89     // If we've set the diagnostic state and are not reporting diagnostics then
     90     // we're done.
     91     if (!SetDiagnostic && !ReportDiags)
     92       break;
     93 
     94     for (unsigned i = 0, e = Opts.Warnings.size(); i != e; ++i) {
     95       StringRef Opt = Opts.Warnings[i];
     96       StringRef OrigOpt = Opts.Warnings[i];
     97 
     98       // Treat -Wformat=0 as an alias for -Wno-format.
     99       if (Opt == "format=0")
    100         Opt = "no-format";
    101 
    102       // Check to see if this warning starts with "no-", if so, this is a
    103       // negative form of the option.
    104       bool isPositive = true;
    105       if (Opt.startswith("no-")) {
    106         isPositive = false;
    107         Opt = Opt.substr(3);
    108       }
    109 
    110       // Figure out how this option affects the warning.  If -Wfoo, map the
    111       // diagnostic to a warning, if -Wno-foo, map it to ignore.
    112       diag::Mapping Mapping = isPositive ? diag::MAP_WARNING : diag::MAP_IGNORE;
    113 
    114       // -Wsystem-headers is a special case, not driven by the option table.  It
    115       // cannot be controlled with -Werror.
    116       if (Opt == "system-headers") {
    117         if (SetDiagnostic)
    118           Diags.setSuppressSystemWarnings(!isPositive);
    119         continue;
    120       }
    121 
    122       // -Weverything is a special case as well.  It implicitly enables all
    123       // warnings, including ones not explicitly in a warning group.
    124       if (Opt == "everything") {
    125         if (SetDiagnostic) {
    126           if (isPositive) {
    127             Diags.setEnableAllWarnings(true);
    128           } else {
    129             Diags.setEnableAllWarnings(false);
    130             Diags.setMappingToAllDiagnostics(diag::MAP_IGNORE);
    131           }
    132         }
    133         continue;
    134       }
    135 
    136       // -Werror/-Wno-error is a special case, not controlled by the option
    137       // table. It also has the "specifier" form of -Werror=foo and -Werror-foo.
    138       if (Opt.startswith("error")) {
    139         StringRef Specifier;
    140         if (Opt.size() > 5) {  // Specifier must be present.
    141           if ((Opt[5] != '=' && Opt[5] != '-') || Opt.size() == 6) {
    142             if (Report)
    143               Diags.Report(diag::warn_unknown_warning_specifier)
    144                 << "-Werror" << ("-W" + OrigOpt.str());
    145             continue;
    146           }
    147           Specifier = Opt.substr(6);
    148         }
    149 
    150         if (Specifier.empty()) {
    151           if (SetDiagnostic)
    152             Diags.setWarningsAsErrors(isPositive);
    153           continue;
    154         }
    155 
    156         if (SetDiagnostic) {
    157           // Set the warning as error flag for this specifier.
    158           Diags.setDiagnosticGroupWarningAsError(Specifier, isPositive);
    159         } else if (DiagIDs->getDiagnosticsInGroup(Specifier, _Diags)) {
    160           EmitUnknownDiagWarning(Diags, "-Werror=", Specifier, isPositive);
    161         }
    162         continue;
    163       }
    164 
    165       // -Wfatal-errors is yet another special case.
    166       if (Opt.startswith("fatal-errors")) {
    167         StringRef Specifier;
    168         if (Opt.size() != 12) {
    169           if ((Opt[12] != '=' && Opt[12] != '-') || Opt.size() == 13) {
    170             if (Report)
    171               Diags.Report(diag::warn_unknown_warning_specifier)
    172                 << "-Wfatal-errors" << ("-W" + OrigOpt.str());
    173             continue;
    174           }
    175           Specifier = Opt.substr(13);
    176         }
    177 
    178         if (Specifier.empty()) {
    179           if (SetDiagnostic)
    180             Diags.setErrorsAsFatal(isPositive);
    181           continue;
    182         }
    183 
    184         if (SetDiagnostic) {
    185           // Set the error as fatal flag for this specifier.
    186           Diags.setDiagnosticGroupErrorAsFatal(Specifier, isPositive);
    187         } else if (DiagIDs->getDiagnosticsInGroup(Specifier, _Diags)) {
    188           EmitUnknownDiagWarning(Diags, "-Wfatal-errors=", Specifier,
    189                                  isPositive);
    190         }
    191         continue;
    192       }
    193 
    194       if (Report) {
    195         if (DiagIDs->getDiagnosticsInGroup(Opt, _Diags))
    196           EmitUnknownDiagWarning(Diags, isPositive ? "-W" : "-Wno-", Opt,
    197                                  isPositive);
    198       } else {
    199         Diags.setDiagnosticGroupMapping(Opt, Mapping);
    200       }
    201     }
    202   }
    203 }
    204