[clang-tools-extra] r328107 - [clang-tidy] Resubmit hicpp-multiway-paths-covered without breaking test
Jonas Toth via cfe-commits
cfe-commits at lists.llvm.org
Wed Mar 21 08:34:15 PDT 2018
Author: jonastoth
Date: Wed Mar 21 08:34:15 2018
New Revision: 328107
URL: http://llvm.org/viewvc/llvm-project?rev=328107&view=rev
Log:
[clang-tidy] Resubmit hicpp-multiway-paths-covered without breaking test
The original check did break the green buildbot in the sanitizer build.
It took a while to redroduce and understand the issue.
There occured a stackoverflow while parsing the AST. The testcase with
256 case labels was the problem because each case label added another
stackframe. It seemed that the issue occured only in 'RelWithDebInfo' builds
and not in normal sanitizer builds.
To simplify the matchers the recognition for the different kinds of switch
statements has been moved into a seperate function and will not be done with
ASTMatchers. This is an attempt to reduce recursion and stacksize as well.
The new check removed this big testcase. Covering all possible values is still
implemented for bitfields and works there. The same logic on integer types
will lead to the issue.
Running it over LLVM gives the following results:
Differential: https://reviews.llvm.org/D40737
Added:
clang-tools-extra/trunk/clang-tidy/hicpp/MultiwayPathsCoveredCheck.cpp
clang-tools-extra/trunk/clang-tidy/hicpp/MultiwayPathsCoveredCheck.h
clang-tools-extra/trunk/docs/clang-tidy/checks/hicpp-multiway-paths-covered.rst
clang-tools-extra/trunk/test/clang-tidy/hicpp-multiway-paths-covered-else.cpp
clang-tools-extra/trunk/test/clang-tidy/hicpp-multiway-paths-covered.cpp
Modified:
clang-tools-extra/trunk/clang-tidy/hicpp/CMakeLists.txt
clang-tools-extra/trunk/clang-tidy/hicpp/HICPPTidyModule.cpp
clang-tools-extra/trunk/docs/ReleaseNotes.rst
clang-tools-extra/trunk/docs/clang-tidy/checks/list.rst
Modified: clang-tools-extra/trunk/clang-tidy/hicpp/CMakeLists.txt
URL: http://llvm.org/viewvc/llvm-project/clang-tools-extra/trunk/clang-tidy/hicpp/CMakeLists.txt?rev=328107&r1=328106&r2=328107&view=diff
==============================================================================
--- clang-tools-extra/trunk/clang-tidy/hicpp/CMakeLists.txt (original)
+++ clang-tools-extra/trunk/clang-tidy/hicpp/CMakeLists.txt Wed Mar 21 08:34:15 2018
@@ -2,6 +2,7 @@ set(LLVM_LINK_COMPONENTS support)
add_clang_library(clangTidyHICPPModule
ExceptionBaseclassCheck.cpp
+ MultiwayPathsCoveredCheck.cpp
NoAssemblerCheck.cpp
HICPPTidyModule.cpp
SignedBitwiseCheck.cpp
Modified: clang-tools-extra/trunk/clang-tidy/hicpp/HICPPTidyModule.cpp
URL: http://llvm.org/viewvc/llvm-project/clang-tools-extra/trunk/clang-tidy/hicpp/HICPPTidyModule.cpp?rev=328107&r1=328106&r2=328107&view=diff
==============================================================================
--- clang-tools-extra/trunk/clang-tidy/hicpp/HICPPTidyModule.cpp (original)
+++ clang-tools-extra/trunk/clang-tidy/hicpp/HICPPTidyModule.cpp Wed Mar 21 08:34:15 2018
@@ -36,6 +36,7 @@
#include "../readability/FunctionSizeCheck.h"
#include "../readability/IdentifierNamingCheck.h"
#include "ExceptionBaseclassCheck.h"
+#include "MultiwayPathsCoveredCheck.h"
#include "NoAssemblerCheck.h"
#include "SignedBitwiseCheck.h"
@@ -54,6 +55,8 @@ public:
"hicpp-deprecated-headers");
CheckFactories.registerCheck<ExceptionBaseclassCheck>(
"hicpp-exception-baseclass");
+ CheckFactories.registerCheck<MultiwayPathsCoveredCheck>(
+ "hicpp-multiway-paths-covered");
CheckFactories.registerCheck<SignedBitwiseCheck>("hicpp-signed-bitwise");
CheckFactories.registerCheck<google::ExplicitConstructorCheck>(
"hicpp-explicit-conversions");
Added: clang-tools-extra/trunk/clang-tidy/hicpp/MultiwayPathsCoveredCheck.cpp
URL: http://llvm.org/viewvc/llvm-project/clang-tools-extra/trunk/clang-tidy/hicpp/MultiwayPathsCoveredCheck.cpp?rev=328107&view=auto
==============================================================================
--- clang-tools-extra/trunk/clang-tidy/hicpp/MultiwayPathsCoveredCheck.cpp (added)
+++ clang-tools-extra/trunk/clang-tidy/hicpp/MultiwayPathsCoveredCheck.cpp Wed Mar 21 08:34:15 2018
@@ -0,0 +1,181 @@
+//===--- MultiwayPathsCoveredCheck.cpp - clang-tidy------------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "MultiwayPathsCoveredCheck.h"
+#include "clang/AST/ASTContext.h"
+
+#include <limits>
+
+using namespace clang::ast_matchers;
+
+namespace clang {
+namespace tidy {
+namespace hicpp {
+
+void MultiwayPathsCoveredCheck::storeOptions(
+ ClangTidyOptions::OptionMap &Opts) {
+ Options.store(Opts, "WarnOnMissingElse", WarnOnMissingElse);
+}
+
+void MultiwayPathsCoveredCheck::registerMatchers(MatchFinder *Finder) {
+ Finder->addMatcher(
+ switchStmt(
+ hasCondition(allOf(
+ // Match on switch statements that have either a bit-field or
+ // an integer condition. The ordering in 'anyOf()' is
+ // important because the last condition is the most general.
+ anyOf(ignoringImpCasts(memberExpr(hasDeclaration(
+ fieldDecl(isBitField()).bind("bitfield")))),
+ ignoringImpCasts(declRefExpr().bind("non-enum-condition"))),
+ // 'unless()' must be the last match here and must be bound,
+ // otherwise the matcher does not work correctly, because it
+ // will not explicitly ignore enum conditions.
+ unless(ignoringImpCasts(
+ declRefExpr(hasType(enumType())).bind("enum-condition"))))))
+ .bind("switch"),
+ this);
+
+ // This option is noisy, therefore matching is configurable.
+ if (WarnOnMissingElse) {
+ Finder->addMatcher(
+ ifStmt(allOf(hasParent(ifStmt()), unless(hasElse(anything()))))
+ .bind("else-if"),
+ this);
+ }
+}
+
+static std::pair<std::size_t, bool> countCaseLabels(const SwitchStmt *Switch) {
+ std::size_t CaseCount = 0;
+ bool HasDefault = false;
+
+ const SwitchCase *CurrentCase = Switch->getSwitchCaseList();
+ while (CurrentCase) {
+ ++CaseCount;
+ if (isa<DefaultStmt>(CurrentCase))
+ HasDefault = true;
+
+ CurrentCase = CurrentCase->getNextSwitchCase();
+ }
+
+ return std::make_pair(CaseCount, HasDefault);
+}
+
+/// This function calculate 2 ** Bits and returns
+/// numeric_limits<std::size_t>::max() if an overflow occured.
+static std::size_t twoPow(std::size_t Bits) {
+ return Bits >= std::numeric_limits<std::size_t>::digits
+ ? std::numeric_limits<std::size_t>::max()
+ : static_cast<size_t>(1) << Bits;
+}
+
+/// Get the number of possible values that can be switched on for the type T.
+///
+/// \return - 0 if bitcount could not be determined
+/// - numeric_limits<std::size_t>::max() when overflow appeared due to
+/// more than 64 bits type size.
+static std::size_t getNumberOfPossibleValues(QualType T,
+ const ASTContext &Context) {
+ // `isBooleanType` must come first because `bool` is an integral type as well
+ // and would not return 2 as result.
+ if (T->isBooleanType())
+ return 2;
+ else if (T->isIntegralType(Context))
+ return twoPow(Context.getTypeSize(T));
+ else
+ return 1;
+}
+
+void MultiwayPathsCoveredCheck::check(const MatchFinder::MatchResult &Result) {
+ if (const auto *ElseIfWithoutElse =
+ Result.Nodes.getNodeAs<IfStmt>("else-if")) {
+ diag(ElseIfWithoutElse->getLocStart(),
+ "potentially uncovered codepath; add an ending else statement");
+ return;
+ }
+ const auto *Switch = Result.Nodes.getNodeAs<SwitchStmt>("switch");
+ std::size_t SwitchCaseCount;
+ bool SwitchHasDefault;
+ std::tie(SwitchCaseCount, SwitchHasDefault) = countCaseLabels(Switch);
+
+ // Checks the sanity of 'switch' statements that actually do define
+ // a default branch but might be degenerated by having no or only one case.
+ if (SwitchHasDefault) {
+ handleSwitchWithDefault(Switch, SwitchCaseCount);
+ return;
+ }
+ // Checks all 'switch' statements that do not define a default label.
+ // Here the heavy lifting happens.
+ if (!SwitchHasDefault && SwitchCaseCount > 0) {
+ handleSwitchWithoutDefault(Switch, SwitchCaseCount, Result);
+ return;
+ }
+ // Warns for degenerated 'switch' statements that neither define a case nor
+ // a default label.
+ // FIXME: Evaluate, if emitting a fix-it to simplify that statement is
+ // reasonable.
+ if (!SwitchHasDefault && SwitchCaseCount == 0) {
+ diag(Switch->getLocStart(),
+ "switch statement without labels has no effect");
+ return;
+ }
+ llvm_unreachable("matched a case, that was not explicitly handled");
+}
+
+void MultiwayPathsCoveredCheck::handleSwitchWithDefault(
+ const SwitchStmt *Switch, std::size_t CaseCount) {
+ assert(CaseCount > 0 && "Switch statement with supposedly one default "
+ "branch did not contain any case labels");
+ if (CaseCount == 1 || CaseCount == 2)
+ diag(Switch->getLocStart(),
+ CaseCount == 1
+ ? "degenerated switch with default label only"
+ : "switch could be better written as an if/else statement");
+}
+
+void MultiwayPathsCoveredCheck::handleSwitchWithoutDefault(
+ const SwitchStmt *Switch, std::size_t CaseCount,
+ const MatchFinder::MatchResult &Result) {
+ // The matcher only works because some nodes are explicitly matched and
+ // bound but ignored. This is necessary to build the excluding logic for
+ // enums and 'switch' statements without a 'default' branch.
+ assert(!Result.Nodes.getNodeAs<DeclRefExpr>("enum-condition") &&
+ "switch over enum is handled by warnings already, explicitly ignoring "
+ "them");
+ // Determine the number of case labels. Because 'default' is not present
+ // and duplicating case labels is not allowed this number represents
+ // the number of codepaths. It can be directly compared to 'MaxPathsPossible'
+ // to see if some cases are missing.
+ // CaseCount == 0 is caught in DegenerateSwitch. Necessary because the
+ // matcher used for here does not match on degenerate 'switch'.
+ assert(CaseCount > 0 && "Switch statement without any case found. This case "
+ "should be excluded by the matcher and is handled "
+ "separatly.");
+ std::size_t MaxPathsPossible = [&]() {
+ if (const auto *GeneralCondition =
+ Result.Nodes.getNodeAs<DeclRefExpr>("non-enum-condition")) {
+ return getNumberOfPossibleValues(GeneralCondition->getType(),
+ *Result.Context);
+ }
+ if (const auto *BitfieldDecl =
+ Result.Nodes.getNodeAs<FieldDecl>("bitfield")) {
+ return twoPow(BitfieldDecl->getBitWidthValue(*Result.Context));
+ }
+
+ return 0ul;
+ }();
+
+ // FIXME: Transform the 'switch' into an 'if' for CaseCount == 1.
+ if (CaseCount < MaxPathsPossible)
+ diag(Switch->getLocStart(),
+ CaseCount == 1 ? "switch with only one case; use an if statement"
+ : "potential uncovered code path; add a default label");
+}
+} // namespace hicpp
+} // namespace tidy
+} // namespace clang
Added: clang-tools-extra/trunk/clang-tidy/hicpp/MultiwayPathsCoveredCheck.h
URL: http://llvm.org/viewvc/llvm-project/clang-tools-extra/trunk/clang-tidy/hicpp/MultiwayPathsCoveredCheck.h?rev=328107&view=auto
==============================================================================
--- clang-tools-extra/trunk/clang-tidy/hicpp/MultiwayPathsCoveredCheck.h (added)
+++ clang-tools-extra/trunk/clang-tidy/hicpp/MultiwayPathsCoveredCheck.h Wed Mar 21 08:34:15 2018
@@ -0,0 +1,51 @@
+//===--- MultiwayPathsCoveredCheck.h - clang-tidy----------------*- C++ -*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_HICPP_MULTIWAY_PATHS_COVERED_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_HICPP_MULTIWAY_PATHS_COVERED_H
+
+#include "../ClangTidy.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include <iostream>
+
+namespace clang {
+namespace tidy {
+namespace hicpp {
+
+/// Find occasions where not all codepaths are explicitly covered in code.
+/// This includes 'switch' without a 'default'-branch and 'if'-'else if'-chains
+/// without a final 'else'-branch.
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/hicpp-multiway-paths-covered.html
+class MultiwayPathsCoveredCheck : public ClangTidyCheck {
+public:
+ MultiwayPathsCoveredCheck(StringRef Name, ClangTidyContext *Context)
+ : ClangTidyCheck(Name, Context),
+ WarnOnMissingElse(Options.get("WarnOnMissingElse", 0)) {}
+ void storeOptions(ClangTidyOptions::OptionMap &Opts) override;
+ void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+ void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+
+private:
+ void handleSwitchWithDefault(const SwitchStmt *Switch, std::size_t CaseCount);
+ void handleSwitchWithoutDefault(
+ const SwitchStmt *Switch, std::size_t CaseCount,
+ const ast_matchers::MatchFinder::MatchResult &Result);
+ /// This option can be configured to warn on missing 'else' branches in an
+ /// 'if-else if' chain. The default is false because this option might be
+ /// noisy on some code bases.
+ const bool WarnOnMissingElse;
+};
+
+} // namespace hicpp
+} // namespace tidy
+} // namespace clang
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_HICPP_MULTIWAY_PATHS_COVERED_H
Modified: clang-tools-extra/trunk/docs/ReleaseNotes.rst
URL: http://llvm.org/viewvc/llvm-project/clang-tools-extra/trunk/docs/ReleaseNotes.rst?rev=328107&r1=328106&r2=328107&view=diff
==============================================================================
--- clang-tools-extra/trunk/docs/ReleaseNotes.rst (original)
+++ clang-tools-extra/trunk/docs/ReleaseNotes.rst Wed Mar 21 08:34:15 2018
@@ -107,6 +107,11 @@ Improvements to clang-tidy
using ``decltype`` specifiers and lambda with otherwise unutterable
return types.
+- New `hicpp-multiway-paths-covered
+ <http://clang.llvm.org/extra/clang-tidy/checks/hicpp-multiway-paths-covered.html>`_ check
+
+ Checks on ``switch`` and ``if`` - ``else if`` constructs that do not cover all possible code paths.
+
- New `modernize-use-uncaught-exceptions
<http://clang.llvm.org/extra/clang-tidy/checks/modernize-use-uncaught-exceptions.html>`_ check
Added: clang-tools-extra/trunk/docs/clang-tidy/checks/hicpp-multiway-paths-covered.rst
URL: http://llvm.org/viewvc/llvm-project/clang-tools-extra/trunk/docs/clang-tidy/checks/hicpp-multiway-paths-covered.rst?rev=328107&view=auto
==============================================================================
--- clang-tools-extra/trunk/docs/clang-tidy/checks/hicpp-multiway-paths-covered.rst (added)
+++ clang-tools-extra/trunk/docs/clang-tidy/checks/hicpp-multiway-paths-covered.rst Wed Mar 21 08:34:15 2018
@@ -0,0 +1,96 @@
+.. title:: clang-tidy - hicpp-multiway-paths-covered
+
+hicpp-multiway-paths-covered
+============================
+
+This check discovers situations where code paths are not fully-covered.
+It furthermore suggests using ``if`` instead of ``switch`` if the code will be more clear.
+The `rule 6.1.2 <http://www.codingstandard.com/rule/6-1-2-explicitly-cover-all-paths-through-multi-way-selection-statements/>`_
+and `rule 6.1.4 <http://www.codingstandard.com/rule/6-1-4-ensure-that-a-switch-statement-has-at-least-two-case-labels-distinct-from-the-default-label/>`_
+of the High Integrity C++ Coding Standard are enforced.
+
+``if-else if`` chains that miss a final ``else`` branch might lead to unexpected
+program execution and be the result of a logical error.
+If the missing ``else`` branch is intended you can leave it empty with a clarifying
+comment.
+This warning can be noisy on some code bases, so it is disabled by default.
+
+.. code-block:: c++
+
+ void f1() {
+ int i = determineTheNumber();
+
+ if(i > 0) {
+ // Some Calculation
+ } else if (i < 0) {
+ // Precondition violated or something else.
+ }
+ // ...
+ }
+
+Similar arguments hold for ``switch`` statements which do not cover all possible code paths.
+
+.. code-block:: c++
+
+ // The missing default branch might be a logical error. It can be kept empty
+ // if there is nothing to do, making it explicit.
+ void f2(int i) {
+ switch (i) {
+ case 0: // something
+ break;
+ case 1: // something else
+ break;
+ }
+ // All other numbers?
+ }
+
+ // Violates this rule as well, but already emits a compiler warning (-Wswitch).
+ enum Color { Red, Green, Blue, Yellow };
+ void f3(enum Color c) {
+ switch (c) {
+ case Red: // We can't drive for now.
+ break;
+ case Green: // We are allowed to drive.
+ break;
+ }
+ // Other cases missing
+ }
+
+
+The `rule 6.1.4 <http://www.codingstandard.com/rule/6-1-4-ensure-that-a-switch-statement-has-at-least-two-case-labels-distinct-from-the-default-label/>`_
+requires every ``switch`` statement to have at least two ``case`` labels other than a `default` label.
+Otherwise, the ``switch`` could be better expressed with an ``if`` statement.
+Degenerated ``switch`` statements without any labels are caught as well.
+
+.. code-block:: c++
+
+ // Degenerated switch that could be better written as `if`
+ int i = 42;
+ switch(i) {
+ case 1: // do something here
+ default: // do somethe else here
+ }
+
+ // Should rather be the following:
+ if (i == 1) {
+ // do something here
+ }
+ else {
+ // do something here
+ }
+
+
+.. code-block:: c++
+
+ // A completly degenerated switch will be diagnosed.
+ int i = 42;
+ switch(i) {}
+
+
+Options
+-------
+
+.. option:: WarnOnMissingElse
+
+ Boolean flag that activates a warning for missing ``else`` branches.
+ Default is `0`.
Modified: clang-tools-extra/trunk/docs/clang-tidy/checks/list.rst
URL: http://llvm.org/viewvc/llvm-project/clang-tools-extra/trunk/docs/clang-tidy/checks/list.rst?rev=328107&r1=328106&r2=328107&view=diff
==============================================================================
--- clang-tools-extra/trunk/docs/clang-tidy/checks/list.rst (original)
+++ clang-tools-extra/trunk/docs/clang-tidy/checks/list.rst Wed Mar 21 08:34:15 2018
@@ -122,6 +122,7 @@ Clang-Tidy Checks
hicpp-invalid-access-moved (redirects to bugprone-use-after-move) <hicpp-invalid-access-moved>
hicpp-member-init (redirects to cppcoreguidelines-pro-type-member-init) <hicpp-member-init>
hicpp-move-const-arg (redirects to performance-move-const-arg) <hicpp-move-const-arg>
+ hicpp-multiway-paths-covered
hicpp-named-parameter (redirects to readability-named-parameter) <hicpp-named-parameter>
hicpp-new-delete-operators (redirects to misc-new-delete-overloads) <hicpp-new-delete-operators>
hicpp-no-array-decay (redirects to cppcoreguidelines-pro-bounds-array-to-pointer-decay) <hicpp-no-array-decay>
Added: clang-tools-extra/trunk/test/clang-tidy/hicpp-multiway-paths-covered-else.cpp
URL: http://llvm.org/viewvc/llvm-project/clang-tools-extra/trunk/test/clang-tidy/hicpp-multiway-paths-covered-else.cpp?rev=328107&view=auto
==============================================================================
--- clang-tools-extra/trunk/test/clang-tidy/hicpp-multiway-paths-covered-else.cpp (added)
+++ clang-tools-extra/trunk/test/clang-tidy/hicpp-multiway-paths-covered-else.cpp Wed Mar 21 08:34:15 2018
@@ -0,0 +1,57 @@
+// RUN: %check_clang_tidy %s hicpp-multiway-paths-covered %t \
+// RUN: -config='{CheckOptions: \
+// RUN: [{key: hicpp-multiway-paths-covered.WarnOnMissingElse, value: 1}]}'\
+// RUN: --
+
+enum OS { Mac,
+ Windows,
+ Linux };
+
+void problematic_if(int i, enum OS os) {
+ if (i > 0) {
+ return;
+ } else if (i < 0) {
+ // CHECK-MESSAGES: [[@LINE-1]]:10: warning: potentially uncovered codepath; add an ending else statement
+ return;
+ }
+
+ // Could be considered as false positive because all paths are covered logically.
+ // I still think this is valid since the possibility of a final 'everything else'
+ // codepath is expected from if-else if.
+ if (i > 0) {
+ return;
+ } else if (i <= 0) {
+ // CHECK-MESSAGES: [[@LINE-1]]:10: warning: potentially uncovered codepath; add an ending else statement
+ return;
+ }
+
+ // Test if nesting of if-else chains does get caught as well.
+ if (os == Mac) {
+ return;
+ } else if (os == Linux) {
+ // These checks are kind of degenerated, but the check will not try to solve
+ // if logically all paths are covered, which is more the area of the static analyzer.
+ if (true) {
+ return;
+ } else if (false) {
+ // CHECK-MESSAGES: [[@LINE-1]]:12: warning: potentially uncovered codepath; add an ending else statement
+ return;
+ }
+ return;
+ } else {
+ /* unreachable */
+ if (true) // check if the parent would match here as well
+ return;
+ // No warning for simple if statements, since it is common to just test one condition
+ // and ignore the opposite.
+ }
+
+ // Ok, because all paths are covered
+ if (i > 0) {
+ return;
+ } else if (i < 0) {
+ return;
+ } else {
+ /* error, maybe precondition failed */
+ }
+}
Added: clang-tools-extra/trunk/test/clang-tidy/hicpp-multiway-paths-covered.cpp
URL: http://llvm.org/viewvc/llvm-project/clang-tools-extra/trunk/test/clang-tidy/hicpp-multiway-paths-covered.cpp?rev=328107&view=auto
==============================================================================
--- clang-tools-extra/trunk/test/clang-tidy/hicpp-multiway-paths-covered.cpp (added)
+++ clang-tools-extra/trunk/test/clang-tidy/hicpp-multiway-paths-covered.cpp Wed Mar 21 08:34:15 2018
@@ -0,0 +1,468 @@
+// RUN: %check_clang_tidy %s hicpp-multiway-paths-covered %t
+
+enum OS { Mac,
+ Windows,
+ Linux };
+
+struct Bitfields {
+ unsigned UInt : 3;
+ int SInt : 1;
+};
+
+int return_integer() { return 42; }
+
+void bad_switch(int i) {
+ switch (i) {
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: switch with only one case; use an if statement
+ case 0:
+ break;
+ }
+ // No default in this switch
+ switch (i) {
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: potential uncovered code path; add a default label
+ case 0:
+ break;
+ case 1:
+ break;
+ case 2:
+ break;
+ }
+
+ // degenerate, maybe even warning
+ switch (i) {
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: switch statement without labels has no effect
+ }
+
+ switch (int j = return_integer()) {
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: potential uncovered code path; add a default label
+ case 0:
+ case 1:
+ case 2:
+ break;
+ }
+
+ // Degenerated, only default case.
+ switch (i) {
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: degenerated switch with default label only
+ default:
+ break;
+ }
+
+ // Degenerated, only one case label and default case -> Better as if-stmt.
+ switch (i) {
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: switch could be better written as an if/else statement
+ case 0:
+ break;
+ default:
+ break;
+ }
+
+ unsigned long long BigNumber = 0;
+ switch (BigNumber) {
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: potential uncovered code path; add a default label
+ case 0:
+ case 1:
+ break;
+ }
+
+ const int &IntRef = i;
+ switch (IntRef) {
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: potential uncovered code path; add a default label
+ case 0:
+ case 1:
+ break;
+ }
+
+ char C = 'A';
+ switch (C) {
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: potential uncovered code path; add a default label
+ case 'A':
+ break;
+ case 'B':
+ break;
+ }
+
+ Bitfields Bf;
+ // UInt has 3 bits size.
+ switch (Bf.UInt) {
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: potential uncovered code path; add a default label
+ case 0:
+ case 1:
+ break;
+ }
+ // All paths explicitly covered.
+ switch (Bf.UInt) {
+ case 0:
+ case 1:
+ case 2:
+ case 3:
+ case 4:
+ case 5:
+ case 6:
+ case 7:
+ break;
+ }
+ // SInt has 1 bit size, so this is somewhat degenerated.
+ switch (Bf.SInt) {
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: switch with only one case; use an if statement
+ case 0:
+ break;
+ }
+ // All paths explicitly covered.
+ switch (Bf.SInt) {
+ case 0:
+ case 1:
+ break;
+ }
+
+ bool Flag = false;
+ switch (Flag) {
+ // CHECK-MESSAGES:[[@LINE-1]]:3: warning: switch with only one case; use an if statement
+ case true:
+ break;
+ }
+
+ switch (Flag) {
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: degenerated switch with default label only
+ default:
+ break;
+ }
+
+ // This `switch` will create a frontend warning from '-Wswitch-bool' but is
+ // ok for this check.
+ switch (Flag) {
+ case true:
+ break;
+ case false:
+ break;
+ }
+}
+
+void unproblematic_switch(unsigned char c) {
+ //
+ switch (c) {
+ case 0:
+ case 1:
+ case 2:
+ case 3:
+ case 4:
+ case 5:
+ case 6:
+ case 7:
+ case 8:
+ case 9:
+ case 10:
+ case 11:
+ case 12:
+ case 13:
+ case 14:
+ case 15:
+ case 16:
+ case 17:
+ case 18:
+ case 19:
+ case 20:
+ case 21:
+ case 22:
+ case 23:
+ case 24:
+ case 25:
+ case 26:
+ case 27:
+ case 28:
+ case 29:
+ case 30:
+ case 31:
+ case 32:
+ case 33:
+ case 34:
+ case 35:
+ case 36:
+ case 37:
+ case 38:
+ case 39:
+ case 40:
+ case 41:
+ case 42:
+ case 43:
+ case 44:
+ case 45:
+ case 46:
+ case 47:
+ case 48:
+ case 49:
+ case 50:
+ case 51:
+ case 52:
+ case 53:
+ case 54:
+ case 55:
+ case 56:
+ case 57:
+ case 58:
+ case 59:
+ case 60:
+ case 61:
+ case 62:
+ case 63:
+ case 64:
+ case 65:
+ case 66:
+ case 67:
+ case 68:
+ case 69:
+ case 70:
+ case 71:
+ case 72:
+ case 73:
+ case 74:
+ case 75:
+ case 76:
+ case 77:
+ case 78:
+ case 79:
+ case 80:
+ case 81:
+ case 82:
+ case 83:
+ case 84:
+ case 85:
+ case 86:
+ case 87:
+ case 88:
+ case 89:
+ case 90:
+ case 91:
+ case 92:
+ case 93:
+ case 94:
+ case 95:
+ case 96:
+ case 97:
+ case 98:
+ case 99:
+ case 100:
+ case 101:
+ case 102:
+ case 103:
+ case 104:
+ case 105:
+ case 106:
+ case 107:
+ case 108:
+ case 109:
+ case 110:
+ case 111:
+ case 112:
+ case 113:
+ case 114:
+ case 115:
+ case 116:
+ case 117:
+ case 118:
+ case 119:
+ case 120:
+ case 121:
+ case 122:
+ case 123:
+ case 124:
+ case 125:
+ case 126:
+ case 127:
+ case 128:
+ case 129:
+ case 130:
+ case 131:
+ case 132:
+ case 133:
+ case 134:
+ case 135:
+ case 136:
+ case 137:
+ case 138:
+ case 139:
+ case 140:
+ case 141:
+ case 142:
+ case 143:
+ case 144:
+ case 145:
+ case 146:
+ case 147:
+ case 148:
+ case 149:
+ case 150:
+ case 151:
+ case 152:
+ case 153:
+ case 154:
+ case 155:
+ case 156:
+ case 157:
+ case 158:
+ case 159:
+ case 160:
+ case 161:
+ case 162:
+ case 163:
+ case 164:
+ case 165:
+ case 166:
+ case 167:
+ case 168:
+ case 169:
+ case 170:
+ case 171:
+ case 172:
+ case 173:
+ case 174:
+ case 175:
+ case 176:
+ case 177:
+ case 178:
+ case 179:
+ case 180:
+ case 181:
+ case 182:
+ case 183:
+ case 184:
+ case 185:
+ case 186:
+ case 187:
+ case 188:
+ case 189:
+ case 190:
+ case 191:
+ case 192:
+ case 193:
+ case 194:
+ case 195:
+ case 196:
+ case 197:
+ case 198:
+ case 199:
+ case 200:
+ case 201:
+ case 202:
+ case 203:
+ case 204:
+ case 205:
+ case 206:
+ case 207:
+ case 208:
+ case 209:
+ case 210:
+ case 211:
+ case 212:
+ case 213:
+ case 214:
+ case 215:
+ case 216:
+ case 217:
+ case 218:
+ case 219:
+ case 220:
+ case 221:
+ case 222:
+ case 223:
+ case 224:
+ case 225:
+ case 226:
+ case 227:
+ case 228:
+ case 229:
+ case 230:
+ case 231:
+ case 232:
+ case 233:
+ case 234:
+ case 235:
+ case 236:
+ case 237:
+ case 238:
+ case 239:
+ case 240:
+ case 241:
+ case 242:
+ case 243:
+ case 244:
+ case 245:
+ case 246:
+ case 247:
+ case 248:
+ case 249:
+ case 250:
+ case 251:
+ case 252:
+ case 253:
+ case 254:
+ case 255:
+ break;
+ }
+
+ // Some paths are covered by the switch and a default case is present.
+ switch (c) {
+ case 1:
+ case 2:
+ case 3:
+ default:
+ break;
+ }
+}
+
+OS return_enumerator() {
+ return Linux;
+}
+
+// Enumpaths are already covered by a warning, this is just to ensure, that there is
+// no interference or false positives.
+// -Wswitch warns about uncovered enum paths and each here described case is already
+// covered.
+void switch_enums(OS os) {
+ switch (os) {
+ case Linux:
+ break;
+ }
+
+ switch (OS another_os = return_enumerator()) {
+ case Linux:
+ break;
+ }
+
+ switch (os) {
+ }
+}
+
+/// All of these cases will not emit a warning per default, but with explicit activation.
+/// Covered in extra test file.
+void problematic_if(int i, enum OS os) {
+ if (i > 0) {
+ return;
+ } else if (i < 0) {
+ return;
+ }
+
+ if (os == Mac) {
+ return;
+ } else if (os == Linux) {
+ if (true) {
+ return;
+ } else if (false) {
+ return;
+ }
+ return;
+ } else {
+ /* unreachable */
+ if (true) // check if the parent would match here as well
+ return;
+ }
+
+ // Ok, because all paths are covered
+ if (i > 0) {
+ return;
+ } else if (i < 0) {
+ return;
+ } else {
+ /* error, maybe precondition failed */
+ }
+}
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