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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/Basic/AllDiagnostics.h"
     24 #include "clang/Basic/Diagnostic.h"
     25 #include "clang/Basic/DiagnosticOptions.h"
     26 #include <algorithm>
     27 #include <cstring>
     28 #include <utility>
     29 using namespace clang;
     30 
     31 // EmitUnknownDiagWarning - Emit a warning and typo hint for unknown warning
     32 // opts
     33 static void EmitUnknownDiagWarning(DiagnosticsEngine &Diags,
     34                                   StringRef Prefix, StringRef Opt,
     35                                   bool isPositive) {
     36   StringRef Suggestion = DiagnosticIDs::getNearestWarningOption(Opt);
     37   if (!Suggestion.empty())
     38     Diags.Report(isPositive? diag::warn_unknown_warning_option_suggest :
     39                              diag::warn_unknown_negative_warning_option_suggest)
     40       << (Prefix.str() += Opt) << (Prefix.str() += Suggestion);
     41   else
     42     Diags.Report(isPositive? diag::warn_unknown_warning_option :
     43                              diag::warn_unknown_negative_warning_option)
     44       << (Prefix.str() += Opt);
     45 }
     46 
     47 void clang::ProcessWarningOptions(DiagnosticsEngine &Diags,
     48                                   const DiagnosticOptions &Opts,
     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   SmallVector<diag::kind, 10> _Diags;
     77   const IntrusiveRefCntPtr< DiagnosticIDs > DiagIDs =
     78     Diags.getDiagnosticIDs();
     79   // We parse the warning options twice.  The first pass sets diagnostic state,
     80   // while the second pass reports warnings/errors.  This has the effect that
     81   // we follow the more canonical "last option wins" paradigm when there are
     82   // conflicting options.
     83   for (unsigned Report = 0, ReportEnd = 2; Report != ReportEnd; ++Report) {
     84     bool SetDiagnostic = (Report == 0);
     85 
     86     // If we've set the diagnostic state and are not reporting diagnostics then
     87     // we're done.
     88     if (!SetDiagnostic && !ReportDiags)
     89       break;
     90 
     91     for (unsigned i = 0, e = Opts.Warnings.size(); i != e; ++i) {
     92       StringRef Opt = Opts.Warnings[i];
     93       StringRef OrigOpt = Opts.Warnings[i];
     94 
     95       // Treat -Wformat=0 as an alias for -Wno-format.
     96       if (Opt == "format=0")
     97         Opt = "no-format";
     98 
     99       // Check to see if this warning starts with "no-", if so, this is a
    100       // negative form of the option.
    101       bool isPositive = true;
    102       if (Opt.startswith("no-")) {
    103         isPositive = false;
    104         Opt = Opt.substr(3);
    105       }
    106 
    107       // Figure out how this option affects the warning.  If -Wfoo, map the
    108       // diagnostic to a warning, if -Wno-foo, map it to ignore.
    109       diag::Severity Mapping =
    110           isPositive ? diag::Severity::Warning : diag::Severity::Ignored;
    111 
    112       // -Wsystem-headers is a special case, not driven by the option table.  It
    113       // cannot be controlled with -Werror.
    114       if (Opt == "system-headers") {
    115         if (SetDiagnostic)
    116           Diags.setSuppressSystemWarnings(!isPositive);
    117         continue;
    118       }
    119 
    120       // -Weverything is a special case as well.  It implicitly enables all
    121       // warnings, including ones not explicitly in a warning group.
    122       if (Opt == "everything") {
    123         if (SetDiagnostic) {
    124           if (isPositive) {
    125             Diags.setEnableAllWarnings(true);
    126           } else {
    127             Diags.setEnableAllWarnings(false);
    128             Diags.setSeverityForAll(diag::Severity::Ignored);
    129           }
    130         }
    131         continue;
    132       }
    133 
    134       // -Werror/-Wno-error is a special case, not controlled by the option
    135       // table. It also has the "specifier" form of -Werror=foo and -Werror-foo.
    136       if (Opt.startswith("error")) {
    137         StringRef Specifier;
    138         if (Opt.size() > 5) {  // Specifier must be present.
    139           if ((Opt[5] != '=' && Opt[5] != '-') || Opt.size() == 6) {
    140             if (Report)
    141               Diags.Report(diag::warn_unknown_warning_specifier)
    142                 << "-Werror" << ("-W" + OrigOpt.str());
    143             continue;
    144           }
    145           Specifier = Opt.substr(6);
    146         }
    147 
    148         if (Specifier.empty()) {
    149           if (SetDiagnostic)
    150             Diags.setWarningsAsErrors(isPositive);
    151           continue;
    152         }
    153 
    154         if (SetDiagnostic) {
    155           // Set the warning as error flag for this specifier.
    156           Diags.setDiagnosticGroupWarningAsError(Specifier, isPositive);
    157         } else if (DiagIDs->getDiagnosticsInGroup(Specifier, _Diags)) {
    158           EmitUnknownDiagWarning(Diags, "-Werror=", Specifier, isPositive);
    159         }
    160         continue;
    161       }
    162 
    163       // -Wfatal-errors is yet another special case.
    164       if (Opt.startswith("fatal-errors")) {
    165         StringRef Specifier;
    166         if (Opt.size() != 12) {
    167           if ((Opt[12] != '=' && Opt[12] != '-') || Opt.size() == 13) {
    168             if (Report)
    169               Diags.Report(diag::warn_unknown_warning_specifier)
    170                 << "-Wfatal-errors" << ("-W" + OrigOpt.str());
    171             continue;
    172           }
    173           Specifier = Opt.substr(13);
    174         }
    175 
    176         if (Specifier.empty()) {
    177           if (SetDiagnostic)
    178             Diags.setErrorsAsFatal(isPositive);
    179           continue;
    180         }
    181 
    182         if (SetDiagnostic) {
    183           // Set the error as fatal flag for this specifier.
    184           Diags.setDiagnosticGroupErrorAsFatal(Specifier, isPositive);
    185         } else if (DiagIDs->getDiagnosticsInGroup(Specifier, _Diags)) {
    186           EmitUnknownDiagWarning(Diags, "-Wfatal-errors=", Specifier,
    187                                  isPositive);
    188         }
    189         continue;
    190       }
    191 
    192       if (Report) {
    193         if (DiagIDs->getDiagnosticsInGroup(Opt, _Diags))
    194           EmitUnknownDiagWarning(Diags, isPositive ? "-W" : "-Wno-", Opt,
    195                                  isPositive);
    196       } else {
    197         Diags.setSeverityForGroup(Opt, Mapping);
    198       }
    199     }
    200   }
    201 }
    202