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 and -Werror-foo.
134       if (Opt.startswith("error")) {
135         StringRef Specifier;
136         if (Opt.size() > 5) {  // Specifier must be present.
137           if ((Opt[5] != '=' && Opt[5] != '-') || Opt.size() == 6) {
138             if (Report)
139               Diags.Report(diag::warn_unknown_warning_specifier)
140                 << "-Werror" << ("-W" + OrigOpt.str());
141             continue;
142           }
143           Specifier = Opt.substr(6);
144         }
145 
146         if (Specifier.empty()) {
147           if (SetDiagnostic)
148             Diags.setWarningsAsErrors(isPositive);
149           continue;
150         }
151 
152         if (SetDiagnostic) {
153           // Set the warning as error flag for this specifier.
154           Diags.setDiagnosticGroupWarningAsError(Specifier, isPositive);
155         } else if (DiagIDs->getDiagnosticsInGroup(Flavor, Specifier, _Diags)) {
156           EmitUnknownDiagWarning(Diags, Flavor, "-Werror=", Specifier);
157         }
158         continue;
159       }
160 
161       // -Wfatal-errors is yet another special case.
162       if (Opt.startswith("fatal-errors")) {
163         StringRef Specifier;
164         if (Opt.size() != 12) {
165           if ((Opt[12] != '=' && Opt[12] != '-') || Opt.size() == 13) {
166             if (Report)
167               Diags.Report(diag::warn_unknown_warning_specifier)
168                 << "-Wfatal-errors" << ("-W" + OrigOpt.str());
169             continue;
170           }
171           Specifier = Opt.substr(13);
172         }
173 
174         if (Specifier.empty()) {
175           if (SetDiagnostic)
176             Diags.setErrorsAsFatal(isPositive);
177           continue;
178         }
179 
180         if (SetDiagnostic) {
181           // Set the error as fatal flag for this specifier.
182           Diags.setDiagnosticGroupErrorAsFatal(Specifier, isPositive);
183         } else if (DiagIDs->getDiagnosticsInGroup(Flavor, Specifier, _Diags)) {
184           EmitUnknownDiagWarning(Diags, Flavor, "-Wfatal-errors=", Specifier);
185         }
186         continue;
187       }
188 
189       if (Report) {
190         if (DiagIDs->getDiagnosticsInGroup(Flavor, Opt, _Diags))
191           EmitUnknownDiagWarning(Diags, Flavor, isPositive ? "-W" : "-Wno-",
192                                  Opt);
193       } else {
194         Diags.setSeverityForGroup(Flavor, Opt, Mapping);
195       }
196     }
197 
198     for (unsigned i = 0, e = Opts.Remarks.size(); i != e; ++i) {
199       StringRef Opt = Opts.Remarks[i];
200       const auto Flavor = diag::Flavor::Remark;
201 
202       // Check to see if this warning starts with "no-", if so, this is a
203       // negative form of the option.
204       bool IsPositive = !Opt.startswith("no-");
205       if (!IsPositive) Opt = Opt.substr(3);
206 
207       auto Severity = IsPositive ? diag::Severity::Remark
208                                  : diag::Severity::Ignored;
209 
210       // -Reverything sets the state of all remarks. Note that all remarks are
211       // in remark groups, so we don't need a separate 'all remarks enabled'
212       // flag.
213       if (Opt == "everything") {
214         if (SetDiagnostic)
215           Diags.setSeverityForAll(Flavor, Severity);
216         continue;
217       }
218 
219       if (Report) {
220         if (DiagIDs->getDiagnosticsInGroup(Flavor, Opt, _Diags))
221           EmitUnknownDiagWarning(Diags, Flavor, IsPositive ? "-R" : "-Rno-",
222                                  Opt);
223       } else {
224         Diags.setSeverityForGroup(Flavor, Opt,
225                                   IsPositive ? diag::Severity::Remark
226                                              : diag::Severity::Ignored);
227       }
228     }
229   }
230 }
231