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>
30using namespace clang;
31
32// EmitUnknownDiagWarning - Emit a warning and typo hint for unknown warning
33// opts
34static 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
44void 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}
234