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. 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