jpakkane created this revision.
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This checks finds all primitive type local variables (integers, doubles,
pointers) that are declared without an initial value. Includes fixit
functionality to initialize said variables with a default value. This is zero
for most types and NaN for floating point types. The use of NaNs is copied from
the D programming language.
Repository:
rCTE Clang Tools Extra
https://reviews.llvm.org/D64671
Files:
clang-tools-extra/clang-tidy/misc/CMakeLists.txt
clang-tools-extra/clang-tidy/misc/InitLocalVariablesCheck.cpp
clang-tools-extra/clang-tidy/misc/InitLocalVariablesCheck.h
clang-tools-extra/clang-tidy/misc/MiscTidyModule.cpp
clang-tools-extra/docs/ReleaseNotes.rst
clang-tools-extra/docs/clang-tidy/checks/list.rst
clang-tools-extra/docs/clang-tidy/checks/misc-init-local-variables.rst
clang-tools-extra/test/clang-tidy/misc-init-local-variables.cpp
Index: clang-tools-extra/test/clang-tidy/misc-init-local-variables.cpp
===================================================================
--- /dev/null
+++ clang-tools-extra/test/clang-tidy/misc-init-local-variables.cpp
@@ -0,0 +1,68 @@
+// RUN: %check_clang_tidy %s misc-init-local-variables %t
+
+#define DO_NOTHING(x) ((void)x)
+
+// Ensure that function declarations are not changed.
+void some_func(int x, double d, bool b, const char *p);
+
+int do_not_modify_me;
+
+typedef struct {
+ int unaltered1;
+ int unaltered2;
+} UnusedStruct;
+
+
+void init_unit_tests() {
+ int x;
+// CHECK-MESSAGES: :[[@LINE-1]]:7: warning: variable 'x' is not initialized [misc-init-local-variables]
+// CHECK-FIXES: {{^}} int x=0;{{$}}
+ int x0=1, x1, x2=2;
+// CHECK-MESSAGES: :[[@LINE-1]]:13: warning: variable 'x1' is not initialized [misc-init-local-variables]
+// CHECK-FIXES: {{^}} int x0=1, x1=0, x2=2;{{$}}
+ int y0, y1=1, y2;
+// CHECK-MESSAGES: :[[@LINE-1]]:7: warning: variable 'y0' is not initialized [misc-init-local-variables]
+// CHECK-MESSAGES: :[[@LINE-2]]:17: warning: variable 'y2' is not initialized [misc-init-local-variables]
+// CHECK-FIXES: {{^}} int y0=0, y1=1, y2=0;{{$}}
+ int hasval = 42;
+
+ float f;
+// CHECK-MESSAGES: :[[@LINE-1]]:9: warning: variable 'f' is not initialized [misc-init-local-variables]
+// CHECK-FIXES: {{^}} float f=(0.0/0.0);{{$}}
+ float fval = 85.0;
+ double d;
+// CHECK-MESSAGES: :[[@LINE-1]]:10: warning: variable 'd' is not initialized [misc-init-local-variables]
+// CHECK-FIXES: {{^}} double d=(0.0/0.0);{{$}}
+ double dval = 99.0;
+
+ bool b;
+// CHECK-MESSAGES: :[[@LINE-1]]:8: warning: variable 'b' is not initialized [misc-init-local-variables]
+// CHECK-FIXES: {{^}} bool b=0;{{$}}
+ bool bval = true;
+
+ const char *ptr;
+// CHECK-MESSAGES: :[[@LINE-1]]:15: warning: variable 'ptr' is not initialized [misc-init-local-variables]
+// CHECK-FIXES: {{^}} const char *ptr=nullptr;{{$}}
+ const char *ptrval = "a string";
+
+ UnusedStruct u;
+
+ DO_NOTHING(x);
+ DO_NOTHING(x0);
+ DO_NOTHING(x1);
+ DO_NOTHING(x2);
+ DO_NOTHING(y0);
+ DO_NOTHING(y1);
+ DO_NOTHING(y2);
+ DO_NOTHING(hasval);
+ DO_NOTHING(f);
+ DO_NOTHING(fval);
+ DO_NOTHING(d);
+ DO_NOTHING(dval);
+ DO_NOTHING(b);
+ DO_NOTHING(bval);
+ DO_NOTHING(ptr);
+ DO_NOTHING(ptrval);
+ DO_NOTHING(u);
+}
+
Index: clang-tools-extra/docs/clang-tidy/checks/misc-init-local-variables.rst
===================================================================
--- /dev/null
+++ clang-tools-extra/docs/clang-tidy/checks/misc-init-local-variables.rst
@@ -0,0 +1,36 @@
+.. title:: clang-tidy - misc-init-local-variables
+
+misc-init-local-variables
+=========================
+
+Finds local variables that are declared without an initial
+value. These may lead to unexpected behaviour if there is a code path
+that reads the variable before assigning to it.
+
+Only integers, booleans, floats, doubles and pointers are checked. The
+fix option initializes all detected values with the value of zero. An
+exception is float and double types, which are initialized to NaN.
+
+As an example a function that looks like this:
+
+.. code-block:: c++
+
+ void function() {
+ int x;
+ char *txt;
+ double d;
+
+ // Rest of the function.
+ }
+
+Would be rewritten to look like this:
+
+.. code-block:: c++
+
+ void function() {
+ int x=0;
+ char *txt=nullptr;
+ double d=(0.0/0.0);
+
+ // Rest of the function.
+ }
Index: clang-tools-extra/docs/clang-tidy/checks/list.rst
===================================================================
--- clang-tools-extra/docs/clang-tidy/checks/list.rst
+++ clang-tools-extra/docs/clang-tidy/checks/list.rst
@@ -189,6 +189,7 @@
llvm-prefer-isa-or-dyn-cast-in-conditionals
llvm-twine-local
misc-definitions-in-headers
+ misc-init-local-variables
misc-misplaced-const
misc-new-delete-overloads
misc-non-copyable-objects
Index: clang-tools-extra/docs/ReleaseNotes.rst
===================================================================
--- clang-tools-extra/docs/ReleaseNotes.rst
+++ clang-tools-extra/docs/ReleaseNotes.rst
@@ -158,6 +158,12 @@
Checks for calls to ``+new`` or overrides of it, which are prohibited by the
Google Objective-C style guide.
+- New :doc:`misc-init-local-variables
+ <clang-tidy/checks/misc-init-local-variables>` check.
+
+ Checks whether there are local variables that are declared without
+ an initial value.
+
- New :doc:`objc-super-self <clang-tidy/checks/objc-super-self>` check.
Finds invocations of ``-self`` on super instances in initializers of
Index: clang-tools-extra/clang-tidy/misc/MiscTidyModule.cpp
===================================================================
--- clang-tools-extra/clang-tidy/misc/MiscTidyModule.cpp
+++ clang-tools-extra/clang-tidy/misc/MiscTidyModule.cpp
@@ -10,6 +10,7 @@
#include "../ClangTidyModule.h"
#include "../ClangTidyModuleRegistry.h"
#include "DefinitionsInHeadersCheck.h"
+#include "InitLocalVariablesCheck.h"
#include "MisplacedConstCheck.h"
#include "NewDeleteOverloadsCheck.h"
#include "NonCopyableObjects.h"
@@ -32,6 +33,8 @@
void addCheckFactories(ClangTidyCheckFactories &CheckFactories) override {
CheckFactories.registerCheck<DefinitionsInHeadersCheck>(
"misc-definitions-in-headers");
+ CheckFactories.registerCheck<InitLocalVariablesCheck>(
+ "misc-init-local-variables");
CheckFactories.registerCheck<MisplacedConstCheck>("misc-misplaced-const");
CheckFactories.registerCheck<NewDeleteOverloadsCheck>(
"misc-new-delete-overloads");
Index: clang-tools-extra/clang-tidy/misc/InitLocalVariablesCheck.h
===================================================================
--- /dev/null
+++ clang-tools-extra/clang-tidy/misc/InitLocalVariablesCheck.h
@@ -0,0 +1,35 @@
+//===--- InitLocalVariablesCheck.h - clang-tidy -----------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MISC_INITLOCALVARIABLESCHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MISC_INITLOCALVARIABLESCHECK_H
+
+#include "../ClangTidyCheck.h"
+
+namespace clang {
+namespace tidy {
+namespace misc {
+
+/// Find uninitialized local variables.
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/misc-init-local-variables.html
+class InitLocalVariablesCheck : public ClangTidyCheck {
+public:
+ InitLocalVariablesCheck(StringRef Name, ClangTidyContext *Context)
+ : ClangTidyCheck(Name, Context) {}
+ void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+ void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+
+};
+
+} // namespace misc
+} // namespace tidy
+} // namespace clang
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MISC_INITLOCALVARIABLESCHECK_H
Index: clang-tools-extra/clang-tidy/misc/InitLocalVariablesCheck.cpp
===================================================================
--- /dev/null
+++ clang-tools-extra/clang-tidy/misc/InitLocalVariablesCheck.cpp
@@ -0,0 +1,62 @@
+//===--- InitLocalVariablesCheck.cpp - clang-tidy -------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+#include "InitLocalVariablesCheck.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang {
+namespace tidy {
+namespace misc {
+
+void InitLocalVariablesCheck::registerMatchers(MatchFinder *Finder) {
+ Finder->addMatcher(varDecl().bind("vardecl"), this);
+}
+
+void InitLocalVariablesCheck::check(const MatchFinder::MatchResult &Result) {
+ const auto *MatchedDecl = Result.Nodes.getNodeAs<VarDecl>("vardecl");
+ const char *replacement = nullptr;
+
+ if(!MatchedDecl->isLocalVarDecl())
+ return;
+ if(MatchedDecl->hasInit())
+ return;
+
+ auto varName = MatchedDecl->getName();
+ if(varName.empty() || varName.front() == '_') {
+ // Some standard library methods such as "be64toh" are implemented
+ // as macros that internally use variable names
+ // like __v. Do not touch those.
+ return;
+ }
+ auto typePtr = MatchedDecl->getType();
+
+ if(typePtr->isIntegerType()) {
+ replacement = "=0";
+ } else if(typePtr->isFloatingType()) {
+ replacement = "=(0.0/0.0)"; // NaN without needing #includes
+ } else if(typePtr->isPointerType()) {
+ if(getLangOpts().CPlusPlus) {
+ replacement = "=nullptr";
+ } else {
+ replacement = "=NULL";
+ }
+ }
+
+ if(replacement) {
+ diag(MatchedDecl->getLocation(), "variable %0 is not initialized")
+ << MatchedDecl;
+ diag(MatchedDecl->getLocation(), "insert initial value", DiagnosticIDs::Note)
+ << FixItHint::CreateInsertion(MatchedDecl->getLocation().getLocWithOffset(varName.size()), replacement);
+ }
+}
+
+} // namespace misc
+} // namespace tidy
+} // namespace clang
Index: clang-tools-extra/clang-tidy/misc/CMakeLists.txt
===================================================================
--- clang-tools-extra/clang-tidy/misc/CMakeLists.txt
+++ clang-tools-extra/clang-tidy/misc/CMakeLists.txt
@@ -2,6 +2,7 @@
add_clang_library(clangTidyMiscModule
DefinitionsInHeadersCheck.cpp
+ InitLocalVariablesCheck.cpp
MiscTidyModule.cpp
MisplacedConstCheck.cpp
NewDeleteOverloadsCheck.cpp
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