hugoeg updated this revision to Diff 162438.
hugoeg marked 2 inline comments as done.
hugoeg added a comment.
added corrections
https://reviews.llvm.org/D51132
Files:
clang-tidy/abseil/AbseilTidyModule.cpp
clang-tidy/abseil/CMakeLists.txt
clang-tidy/abseil/RedundantStrcatCallsCheck.cpp
clang-tidy/abseil/RedundantStrcatCallsCheck.h
docs/ReleaseNotes.rst
docs/clang-tidy/checks/abseil-redundant-strcat-calls.rst
docs/clang-tidy/checks/list.rst
test/clang-tidy/abseil-redundant-strcat-calls.cpp
Index: test/clang-tidy/abseil-redundant-strcat-calls.cpp
===================================================================
--- test/clang-tidy/abseil-redundant-strcat-calls.cpp
+++ test/clang-tidy/abseil-redundant-strcat-calls.cpp
@@ -0,0 +1,188 @@
+// RUN: %check_clang_tidy %s abseil-redundant-strcat-calls %t
+
+int strlen(const char *);
+
+// Here we mimic the hierarchy of ::string.
+// We need to do so because we are matching on the fully qualified name of the
+// methods.
+struct __sso_string_base {};
+namespace __gnu_cxx {
+template <typename A, typename B, typename C, typename D = __sso_string_base>
+class __versa_string {
+ public:
+ const char *c_str() const;
+ const char *data() const;
+ int size() const;
+ int capacity() const;
+ int length() const;
+ bool empty() const;
+ char &operator[](int);
+ void clear();
+ void resize(int);
+ int compare(const __versa_string &) const;
+};
+} // namespace __gnu_cxx
+
+namespace std {
+template <typename T>
+class char_traits {};
+template <typename T>
+class allocator {};
+} // namespace std
+
+template <typename A, typename B = std::char_traits<A>,
+ typename C = std::allocator<A>>
+class basic_string : public __gnu_cxx::__versa_string<A, B, C> {
+ public:
+ basic_string();
+ basic_string(const basic_string &);
+ basic_string(const char *, C = C());
+ basic_string(const char *, int, C = C());
+ basic_string(const basic_string &, int, int, C = C());
+ ~basic_string();
+
+ basic_string &operator+=(const basic_string &);
+};
+
+template <typename A, typename B, typename C>
+basic_string<A, B, C> operator+(const basic_string<A, B, C> &,
+ const basic_string<A, B, C> &);
+template <typename A, typename B, typename C>
+basic_string<A, B, C> operator+(const basic_string<A, B, C> &, const char *);
+
+typedef basic_string<char> string;
+
+bool operator==(const string &, const string &);
+bool operator==(const string &, const char *);
+bool operator==(const char *, const string &);
+
+bool operator!=(const string &, const string &);
+bool operator<(const string &, const string &);
+bool operator>(const string &, const string &);
+bool operator<=(const string &, const string &);
+bool operator>=(const string &, const string &);
+
+namespace std {
+template <typename _CharT, typename _Traits = char_traits<_CharT>,
+ typename _Alloc = allocator<_CharT>>
+class basic_string;
+
+template <typename _CharT, typename _Traits, typename _Alloc>
+class basic_string {
+ public:
+ basic_string();
+ basic_string(const basic_string &);
+ basic_string(const char *, const _Alloc & = _Alloc());
+ basic_string(const char *, int, const _Alloc & = _Alloc());
+ basic_string(const basic_string &, int, int, const _Alloc & = _Alloc());
+ ~basic_string();
+
+ basic_string &operator+=(const basic_string &);
+
+ unsigned size() const;
+ unsigned length() const;
+ bool empty() const;
+};
+
+typedef basic_string<char> string;
+} // namespace std
+
+namespace absl {
+
+class string_view {
+ public:
+ typedef std::char_traits<char> traits_type;
+
+ string_view();
+ string_view(const char *);
+ string_view(const string &);
+ string_view(const char *, int);
+ string_view(string_view, int);
+
+ template <typename A>
+ explicit operator ::basic_string<char, traits_type, A>() const;
+
+ const char *data() const;
+ int size() const;
+ int length() const;
+};
+
+bool operator==(string_view A, string_view B);
+
+struct AlphaNum {
+ AlphaNum(int i);
+ AlphaNum(double f);
+ AlphaNum(const char *c_str);
+ AlphaNum(const string &str);
+ AlphaNum(const string_view &pc);
+
+ private:
+ AlphaNum(const AlphaNum &);
+ AlphaNum &operator=(const AlphaNum &);
+};
+
+string StrCat(const AlphaNum &A);
+string StrCat(const AlphaNum &A, const AlphaNum &B);
+string StrCat(const AlphaNum &A, const AlphaNum &B, const AlphaNum &C);
+string StrCat(const AlphaNum &A, const AlphaNum &B, const AlphaNum &C,
+ const AlphaNum &D);
+
+// Support 5 or more arguments
+template <typename... AV>
+string StrCat(const AlphaNum &A, const AlphaNum &B, const AlphaNum &C,
+ const AlphaNum &D, const AlphaNum &E, const AV &... args);
+
+void StrAppend(string *Dest, const AlphaNum &A);
+void StrAppend(string *Dest, const AlphaNum &A, const AlphaNum &B);
+void StrAppend(string *Dest, const AlphaNum &A, const AlphaNum &B,
+ const AlphaNum &C);
+void StrAppend(string *Dest, const AlphaNum &A, const AlphaNum &B,
+ const AlphaNum &C, const AlphaNum &D);
+
+// Support 5 or more arguments
+template <typename... AV>
+void StrAppend(string *Dest, const AlphaNum &A, const AlphaNum &B,
+ const AlphaNum &C, const AlphaNum &D, const AlphaNum &E,
+ const AV &... args);
+
+} // namespace absl
+
+using absl::AlphaNum;
+using absl::StrAppend;
+using absl::StrCat;
+
+void Positives() {
+ string S = StrCat(1, StrCat("A", StrCat(1.1)));
+ // CHECK-MESSAGES: [[@LINE-1]]:14: warning: multiple calls to 'absl::StrCat' can be flattened into a single call
+
+ S = StrCat(StrCat(StrCat(StrCat(StrCat(1)))));
+ // CHECK-MESSAGES: [[@LINE-1]]:7: warning: multiple calls to 'absl::StrCat' can be flattened into a single call
+
+ // TODO: should trigger. The issue here is that in the current
+ // implementation we ignore any StrCat with StrCat ancestors. Therefore
+ // inserting anything in between calls will disable triggering the deepest
+ // ones.
+ // s = StrCat(Identity(StrCat(StrCat(1, 2), StrCat(3, 4))));
+
+ StrAppend(&S, 001, StrCat(1, 2, "3"), StrCat("FOO"));
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: multiple calls to 'absl::StrCat' can be flattened into a single call
+
+ StrAppend(&S, 001, StrCat(StrCat(1, 2), "3"), StrCat("FOO"));
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: multiple calls to 'absl::StrCat' can be flattened into a single call
+
+ // Too many args. Ignore for now.
+ S = StrCat(1, 2, StrCat(3, 4, 5, 6, 7), 8, 9, 10,
+ StrCat(11, 12, 13, 14, 15, 16, 17, 18), 19, 20, 21, 22, 23, 24, 25,
+ 26, 27);
+ // CHECK-MESSAGES: :[[@LINE-3]]:7: warning: multiple calls to 'absl::StrCat' can be flattened into a single call
+ StrAppend(&S, StrCat(1, 2, 3, 4, 5), StrCat(6, 7, 8, 9, 10));
+ // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: multiple calls to 'absl::StrCat' can be flattened into a single call
+}
+
+void Negatives() {
+ // One arg. It is used for conversion. Ignore.
+ string S = StrCat(1);
+
+#define A_MACRO(x, y, z) StrCat(x, y, z)
+ S = A_MACRO(1, 2, StrCat("A", "B"));
+}
Index: docs/clang-tidy/checks/list.rst
===================================================================
--- docs/clang-tidy/checks/list.rst
+++ docs/clang-tidy/checks/list.rst
@@ -6,6 +6,7 @@
.. toctree::
abseil-duration-division
abseil-faster-strsplit-delimiter
+ abseil-redundant-strcat-calls
abseil-string-find-startswith
android-cloexec-accept
android-cloexec-accept4
Index: docs/clang-tidy/checks/abseil-redundant-strcat-calls.rst
===================================================================
--- docs/clang-tidy/checks/abseil-redundant-strcat-calls.rst
+++ docs/clang-tidy/checks/abseil-redundant-strcat-calls.rst
@@ -0,0 +1,19 @@
+.. title:: clang-tidy - abseil-redundant-strcat-calls
+
+abseil-redundant-strcat-calls
+=============================
+
+Suggests removal of unnecessary calls to ``absl::StrCat`` when the result is
+being passed to another call to ``absl::StrCat`` or ``absl::StrAppend``.
+
+The extra calls cause unnecessary temporary strings to be constructed. Removing
+them makes the code smaller and faster.
+
+Examples:
+
+.. code-block:: c++
+
+ std::string s = absl::StrCat("A", absl::StrCat("B", absll::StrCat("C", "D")));
+ std::string s = absl::StrCat("A", "B", "C", "D");
+ absl::StrAppend(&s, absl::StrCat("E", "F", "G"));
+ absl::StrAppend(&s, "E", "F", "G");
Index: docs/ReleaseNotes.rst
===================================================================
--- docs/ReleaseNotes.rst
+++ docs/ReleaseNotes.rst
@@ -69,7 +69,13 @@
Finds instances of ``absl::StrSplit()`` or ``absl::MaxSplits()`` where the
delimiter is a single character string literal and replaces with a character.
+
+- New :doc:`abseil-redundant-strcat-calls
+ <clang-tidy/checks/abseil-redundant-strcat-calls>` check.
+ Suggests removal of unnecessary calls to ``absl::StrCat`` when the result is
+ being passed to another ``absl::StrCat`` or ``absl::StrAppend``.
+
- New :doc:`readability-magic-numbers
<clang-tidy/checks/readability-magic-numbers>` check.
Index: clang-tidy/abseil/RedundantStrcatCallsCheck.h
===================================================================
--- clang-tidy/abseil/RedundantStrcatCallsCheck.h
+++ clang-tidy/abseil/RedundantStrcatCallsCheck.h
@@ -0,0 +1,39 @@
+//===--- RedundantStrcatCallsCheck.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_ABSEIL_REDUNDANTSTRCATCALLSCHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_ABSEIL_REDUNDANTSTRCATCALLSCHECK_H
+
+#include "../ClangTidy.h"
+
+namespace clang {
+namespace tidy {
+namespace abseil {
+
+/// Flags redundant calls to absl::StrCat when the result is being passed to
+/// another call of absl::StrCat/absl::StrAppend. Also suggests a fix to
+/// collapse the calls.
+/// Example:
+/// StrCat(1, StrCat(2, 3)) ==> StrCat(1, 2, 3)
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/abseil-redundant-strcat-calls.html
+class RedundantStrcatCallsCheck : public ClangTidyCheck {
+public:
+ RedundantStrcatCallsCheck(StringRef Name, ClangTidyContext *Context)
+ : ClangTidyCheck(Name, Context) {}
+ void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+ void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+};
+
+} // namespace abseil
+} // namespace tidy
+} // namespace clang
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_ABSEIL_REDUNDANTSTRCATCALLSCHECK_H
Index: clang-tidy/abseil/RedundantStrcatCallsCheck.cpp
===================================================================
--- clang-tidy/abseil/RedundantStrcatCallsCheck.cpp
+++ clang-tidy/abseil/RedundantStrcatCallsCheck.cpp
@@ -0,0 +1,140 @@
+//===--- RedundantStrcatCallsCheck.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 "RedundantStrcatCallsCheck.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang {
+namespace tidy {
+namespace abseil {
+
+// TODO: Features to add to the check:
+// - Make it work if num_args > 26.
+// - Remove empty literal string arguments.
+// - Collapse consecutive literal string arguments into one (remove the ,).
+// - Replace StrCat(a + b) -> StrCat(a, b) if a or b are strings.
+// - Make it work in macros if the outer and inner StrCats are both in the
+// argument.
+
+void RedundantStrcatCallsCheck::registerMatchers(MatchFinder* Finder) {
+ if (!getLangOpts().CPlusPlus)
+ return;
+ const auto CallToStrcat =
+ callExpr(callee(functionDecl(hasName("::absl::StrCat"))));
+ const auto CallToStrappend =
+ callExpr(callee(functionDecl(hasName("::absl::StrAppend"))));
+ // Do not match StrCat() calls that are descendants of other StrCat calls.
+ // Those are handled on the ancestor call.
+ const auto CallToEither = callExpr(
+ callee(functionDecl(hasAnyName("::absl::StrCat", "::absl::StrAppend"))));
+ Finder->addMatcher(
+ callExpr(CallToStrcat, unless(hasAncestor(CallToEither))).bind("StrCat"),
+ this);
+ Finder->addMatcher(CallToStrappend.bind("StrAppend"), this);
+}
+
+namespace {
+
+struct StrCatCheckResult {
+ int NumCalls = 0;
+ std::vector<FixItHint> Hints;
+};
+
+void RemoveCallLeaveArgs(const CallExpr* Call, StrCatCheckResult* CheckResult) {
+ // Remove 'Foo('
+ CheckResult->Hints.push_back(
+ FixItHint::CreateRemoval(CharSourceRange::getCharRange(
+ Call->getBeginLoc(), Call->getArg(0)->getBeginLoc())));
+ // Remove the ')'
+ CheckResult->Hints.push_back(
+ FixItHint::CreateRemoval(CharSourceRange::getCharRange(
+ Call->getRParenLoc(), Call->getEndLoc().getLocWithOffset(1))));
+}
+
+const clang::CallExpr* ProcessArgument(const Expr* Arg,
+ const MatchFinder::MatchResult& Result,
+ StrCatCheckResult* CheckResult) {
+ const auto IsAlphanum = hasDeclaration(cxxMethodDecl(hasName("AlphaNum")));
+ static const auto* const Strcat = new auto(hasName("::absl::StrCat"));
+ const auto IsStrcat = cxxBindTemporaryExpr(
+ has(callExpr(callee(functionDecl(*Strcat))).bind("StrCat")));
+ if (const auto* SubStrcatCall = selectFirst<const CallExpr>(
+ "StrCat",
+ match(stmt(anyOf(
+ cxxConstructExpr(IsAlphanum, hasArgument(0, IsStrcat)),
+ IsStrcat)),
+ *Arg->IgnoreParenImpCasts(), *Result.Context))) {
+ RemoveCallLeaveArgs(SubStrcatCall, CheckResult);
+ return SubStrcatCall;
+ }
+ return nullptr;
+}
+
+StrCatCheckResult ProcessCall(const CallExpr* RootCall, bool IsAppend,
+ const MatchFinder::MatchResult& Result) {
+ StrCatCheckResult CheckResult;
+ std::deque<const CallExpr*> CallsToProcess = {RootCall};
+
+ while (!CallsToProcess.empty()) {
+ ++CheckResult.NumCalls;
+
+ const CallExpr* CallExpr = CallsToProcess.front();
+ CallsToProcess.pop_front();
+
+ int StartArg = CallExpr == RootCall && IsAppend;
+ for (const auto *Arg : CallExpr->arguments()) {
+ if (StartArg-- > 0)
+ continue;
+ if (const clang::CallExpr* Sub =
+ ProcessArgument(Arg, Result, &CheckResult)) {
+ CallsToProcess.push_back(Sub);
+ }
+ }
+ }
+ return CheckResult;
+}
+} // namespace
+
+void RedundantStrcatCallsCheck::check(const MatchFinder::MatchResult& Result) {
+ bool IsAppend;
+
+ const CallExpr* RootCall;
+ if ((RootCall = Result.Nodes.getNodeAs<CallExpr>("StrCat")))
+ IsAppend = false;
+ else if ((RootCall = Result.Nodes.getNodeAs<CallExpr>("StrAppend")))
+ IsAppend = true;
+ else
+ return;
+
+ if (RootCall->getBeginLoc().isMacroID()) {
+ // Ignore calls within macros.
+ // In many cases the outer StrCat part of the macro and the inner StrCat is
+ // a macro argument. Removing the inner StrCat() converts one macro
+ // argument into many.
+ return;
+ }
+
+ const StrCatCheckResult CheckResult =
+ ProcessCall(RootCall, IsAppend, Result);
+ if (CheckResult.NumCalls == 1) {
+ // Just one call, so nothing to fix.
+ return;
+ }
+
+ diag(RootCall->getBeginLoc(),
+ "multiple calls to 'absl::StrCat' can be flattened into a single call")
+ << CheckResult.Hints;
+}
+
+} // namespace abseil
+} // namespace tidy
+} // namespace clang
Index: clang-tidy/abseil/CMakeLists.txt
===================================================================
--- clang-tidy/abseil/CMakeLists.txt
+++ clang-tidy/abseil/CMakeLists.txt
@@ -4,6 +4,7 @@
AbseilTidyModule.cpp
DurationDivisionCheck.cpp
FasterStrsplitDelimiterCheck.cpp
+ RedundantStrcatCallsCheck.cpp
StringFindStartswithCheck.cpp
LINK_LIBS
Index: clang-tidy/abseil/AbseilTidyModule.cpp
===================================================================
--- clang-tidy/abseil/AbseilTidyModule.cpp
+++ clang-tidy/abseil/AbseilTidyModule.cpp
@@ -12,6 +12,7 @@
#include "../ClangTidyModuleRegistry.h"
#include "DurationDivisionCheck.h"
#include "FasterStrsplitDelimiterCheck.h"
+#include "RedundantStrcatCallsCheck.h"
#include "StringFindStartswithCheck.h"
namespace clang {
@@ -25,6 +26,8 @@
"abseil-duration-division");
CheckFactories.registerCheck<FasterStrsplitDelimiterCheck>(
"abseil-faster-strsplit-delimiter");
+ CheckFactories.registerCheck<RedundantStrcatCallsCheck>(
+ "abseil-redundant-strcat-calls");
CheckFactories.registerCheck<StringFindStartswithCheck>(
"abseil-string-find-startswith");
}
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