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(DiagnosticsEngine::Ext_Error);
71   else if (Opts.Pedantic)
72     Diags.setExtensionHandlingBehavior(DiagnosticsEngine::Ext_Warn);
73   else
74     Diags.setExtensionHandlingBehavior(DiagnosticsEngine::Ext_Ignore);
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::Mapping Mapping = isPositive ? diag::MAP_WARNING : diag::MAP_IGNORE;
110 
111       // -Wsystem-headers is a special case, not driven by the option table.  It
112       // cannot be controlled with -Werror.
113       if (Opt == "system-headers") {
114         if (SetDiagnostic)
115           Diags.setSuppressSystemWarnings(!isPositive);
116         continue;
117       }
118 
119       // -Weverything is a special case as well.  It implicitly enables all
120       // warnings, including ones not explicitly in a warning group.
121       if (Opt == "everything") {
122         if (SetDiagnostic) {
123           if (isPositive) {
124             Diags.setEnableAllWarnings(true);
125           } else {
126             Diags.setEnableAllWarnings(false);
127             Diags.setMappingToAllDiagnostics(diag::MAP_IGNORE);
128           }
129         }
130         continue;
131       }
132 
133       // -Werror/-Wno-error is a special case, not controlled by the option
134       // table. It also has the "specifier" form of -Werror=foo and -Werror-foo.
135       if (Opt.startswith("error")) {
136         StringRef Specifier;
137         if (Opt.size() > 5) {  // Specifier must be present.
138           if ((Opt[5] != '=' && Opt[5] != '-') || Opt.size() == 6) {
139             if (Report)
140               Diags.Report(diag::warn_unknown_warning_specifier)
141                 << "-Werror" << ("-W" + OrigOpt.str());
142             continue;
143           }
144           Specifier = Opt.substr(6);
145         }
146 
147         if (Specifier.empty()) {
148           if (SetDiagnostic)
149             Diags.setWarningsAsErrors(isPositive);
150           continue;
151         }
152 
153         if (SetDiagnostic) {
154           // Set the warning as error flag for this specifier.
155           Diags.setDiagnosticGroupWarningAsError(Specifier, isPositive);
156         } else if (DiagIDs->getDiagnosticsInGroup(Specifier, _Diags)) {
157           EmitUnknownDiagWarning(Diags, "-Werror=", Specifier, isPositive);
158         }
159         continue;
160       }
161 
162       // -Wfatal-errors is yet another special case.
163       if (Opt.startswith("fatal-errors")) {
164         StringRef Specifier;
165         if (Opt.size() != 12) {
166           if ((Opt[12] != '=' && Opt[12] != '-') || Opt.size() == 13) {
167             if (Report)
168               Diags.Report(diag::warn_unknown_warning_specifier)
169                 << "-Wfatal-errors" << ("-W" + OrigOpt.str());
170             continue;
171           }
172           Specifier = Opt.substr(13);
173         }
174 
175         if (Specifier.empty()) {
176           if (SetDiagnostic)
177             Diags.setErrorsAsFatal(isPositive);
178           continue;
179         }
180 
181         if (SetDiagnostic) {
182           // Set the error as fatal flag for this specifier.
183           Diags.setDiagnosticGroupErrorAsFatal(Specifier, isPositive);
184         } else if (DiagIDs->getDiagnosticsInGroup(Specifier, _Diags)) {
185           EmitUnknownDiagWarning(Diags, "-Wfatal-errors=", Specifier,
186                                  isPositive);
187         }
188         continue;
189       }
190 
191       if (Report) {
192         if (DiagIDs->getDiagnosticsInGroup(Opt, _Diags))
193           EmitUnknownDiagWarning(Diags, isPositive ? "-W" : "-Wno-", Opt,
194                                  isPositive);
195       } else {
196         Diags.setDiagnosticGroupMapping(Opt, Mapping);
197       }
198     }
199   }
200 }
201