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
EmitUnknownDiagWarning(DiagnosticsEngine & Diags,diag::Flavor Flavor,StringRef Prefix,StringRef Opt)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 
ProcessWarningOptions(DiagnosticsEngine & Diags,const DiagnosticOptions & Opts,bool ReportDiags)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 = !Opt.consume_front("no-");
100 
101       // Figure out how this option affects the warning.  If -Wfoo, map the
102       // diagnostic to a warning, if -Wno-foo, map it to ignore.
103       diag::Severity Mapping =
104           isPositive ? diag::Severity::Warning : diag::Severity::Ignored;
105 
106       // -Wsystem-headers is a special case, not driven by the option table.  It
107       // cannot be controlled with -Werror.
108       if (Opt == "system-headers") {
109         if (SetDiagnostic)
110           Diags.setSuppressSystemWarnings(!isPositive);
111         continue;
112       }
113 
114       // -Weverything is a special case as well.  It implicitly enables all
115       // warnings, including ones not explicitly in a warning group.
116       if (Opt == "everything") {
117         if (SetDiagnostic) {
118           if (isPositive) {
119             Diags.setEnableAllWarnings(true);
120           } else {
121             Diags.setEnableAllWarnings(false);
122             Diags.setSeverityForAll(Flavor, diag::Severity::Ignored);
123           }
124         }
125         continue;
126       }
127 
128       // -Werror/-Wno-error is a special case, not controlled by the option
129       // table. It also has the "specifier" form of -Werror=foo. GCC supports
130       // the deprecated -Werror-implicit-function-declaration which is used by
131       // a few projects.
132       if (Opt.starts_with("error")) {
133         StringRef Specifier;
134         if (Opt.size() > 5) {  // Specifier must be present.
135           if (Opt[5] != '=' &&
136               Opt.substr(5) != "-implicit-function-declaration") {
137             if (Report)
138               Diags.Report(diag::warn_unknown_warning_specifier)
139                 << "-Werror" << ("-W" + OrigOpt.str());
140             continue;
141           }
142           Specifier = Opt.substr(6);
143         }
144 
145         if (Specifier.empty()) {
146           if (SetDiagnostic)
147             Diags.setWarningsAsErrors(isPositive);
148           continue;
149         }
150 
151         if (SetDiagnostic) {
152           // Set the warning as error flag for this specifier.
153           Diags.setDiagnosticGroupWarningAsError(Specifier, isPositive);
154         } else if (DiagIDs->getDiagnosticsInGroup(Flavor, Specifier, _Diags)) {
155           EmitUnknownDiagWarning(Diags, Flavor, "-Werror=", Specifier);
156         }
157         continue;
158       }
159 
160       // -Wfatal-errors is yet another special case.
161       if (Opt.starts_with("fatal-errors")) {
162         StringRef Specifier;
163         if (Opt.size() != 12) {
164           if ((Opt[12] != '=' && Opt[12] != '-') || Opt.size() == 13) {
165             if (Report)
166               Diags.Report(diag::warn_unknown_warning_specifier)
167                 << "-Wfatal-errors" << ("-W" + OrigOpt.str());
168             continue;
169           }
170           Specifier = Opt.substr(13);
171         }
172 
173         if (Specifier.empty()) {
174           if (SetDiagnostic)
175             Diags.setErrorsAsFatal(isPositive);
176           continue;
177         }
178 
179         if (SetDiagnostic) {
180           // Set the error as fatal flag for this specifier.
181           Diags.setDiagnosticGroupErrorAsFatal(Specifier, isPositive);
182         } else if (DiagIDs->getDiagnosticsInGroup(Flavor, Specifier, _Diags)) {
183           EmitUnknownDiagWarning(Diags, Flavor, "-Wfatal-errors=", Specifier);
184         }
185         continue;
186       }
187 
188       if (Report) {
189         if (DiagIDs->getDiagnosticsInGroup(Flavor, Opt, _Diags))
190           EmitUnknownDiagWarning(Diags, Flavor, isPositive ? "-W" : "-Wno-",
191                                  Opt);
192       } else {
193         Diags.setSeverityForGroup(Flavor, Opt, Mapping);
194       }
195     }
196 
197     for (StringRef Opt : Opts.Remarks) {
198       const auto Flavor = diag::Flavor::Remark;
199 
200       // Check to see if this warning starts with "no-", if so, this is a
201       // negative form of the option.
202       bool IsPositive = !Opt.consume_front("no-");
203 
204       auto Severity = IsPositive ? diag::Severity::Remark
205                                  : diag::Severity::Ignored;
206 
207       // -Reverything sets the state of all remarks. Note that all remarks are
208       // in remark groups, so we don't need a separate 'all remarks enabled'
209       // flag.
210       if (Opt == "everything") {
211         if (SetDiagnostic)
212           Diags.setSeverityForAll(Flavor, Severity);
213         continue;
214       }
215 
216       if (Report) {
217         if (DiagIDs->getDiagnosticsInGroup(Flavor, Opt, _Diags))
218           EmitUnknownDiagWarning(Diags, Flavor, IsPositive ? "-R" : "-Rno-",
219                                  Opt);
220       } else {
221         Diags.setSeverityForGroup(Flavor, Opt,
222                                   IsPositive ? diag::Severity::Remark
223                                              : diag::Severity::Ignored);
224       }
225     }
226   }
227 }
228