[clang-tidy] Fix false-positives in readability-container-size-empty (#74140)

Added support for size-like method returning signed type, and corrected
false positive caused by always-false check for size bellow zero.

Closes #72619

1 files changed, 52 insertions, 6 deletions

diff --git a/clang-tools-extra/test/clang-tidy/checkers/readability/container-size-empty.cpp b/clang-tools-extra/test/clang-tidy/checkers/readability/container-size-empty.cpp
index 3b9e060..84bdbd5 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/readability/container-size-empty.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/readability/container-size-empty.cpp
@@ -33,7 +33,7 @@ class TemplatedContainer {
 public:
   bool operator==(const TemplatedContainer<T>& other) const;
   bool operator!=(const TemplatedContainer<T>& other) const;
-  int size() const;
+  unsigned long size() const;
   bool empty() const;
 };
 
@@ -42,7 +42,7 @@ class PrivateEmpty {
 public:
   bool operator==(const PrivateEmpty<T>& other) const;
   bool operator!=(const PrivateEmpty<T>& other) const;
-  int size() const;
+  unsigned long size() const;
 private:
   bool empty() const;
 };
@@ -61,7 +61,7 @@ struct EnumSize {
 class Container {
 public:
   bool operator==(const Container& other) const;
-  int size() const;
+  unsigned long size() const;
   bool empty() const;
 };
 
@@ -70,13 +70,13 @@ class Derived : public Container {
 
 class Container2 {
 public:
-  int size() const;
+  unsigned long size() const;
   bool empty() const { return size() == 0; }
 };
 
 class Container3 {
 public:
-  int size() const;
+  unsigned long size() const;
   bool empty() const;
 };
 
@@ -85,7 +85,7 @@ bool Container3::empty() const { return this->size() == 0; }
 class Container4 {
 public:
   bool operator==(const Container4& rhs) const;
-  int size() const;
+  unsigned long size() const;
   bool empty() const { return *this == Container4(); }
 };
 
@@ -815,3 +815,49 @@ bool testNotEmptyStringLiterals(const std::string& s)
   using namespace std::string_literals;
   return s == "foo"s;
 }
+
+namespace PR72619 {
+  struct SS {
+    bool empty() const;
+    int size() const;
+  };
+
+  struct SU {
+    bool empty() const;
+    unsigned size() const;
+  };
+
+  void f(const SU& s) {
+    if (s.size() < 0) {}
+    if (0 > s.size()) {}
+    if (s.size() >= 0) {}
+    if (0 <= s.size()) {}
+    if (s.size() < 1)
+      ;
+    // CHECK-MESSAGES: :[[@LINE-2]]:9: warning: the 'empty' method should be used to check for emptiness instead of 'size' [readability-container-size-empty]
+    // CHECK-FIXES: {{^    }}if (s.empty()){{$}}
+    if (1 > s.size())
+      ;
+    // CHECK-MESSAGES: :[[@LINE-2]]:13: warning: the 'empty' method should be used to check for emptiness instead of 'size' [readability-container-size-empty]
+    // CHECK-FIXES: {{^    }}if (s.empty()){{$}}
+    if (s.size() <= 0)
+      ;
+    // CHECK-MESSAGES: :[[@LINE-2]]:9: warning: the 'empty' method should be used to check for emptiness instead of 'size' [readability-container-size-empty]
+    // CHECK-FIXES: {{^    }}if (s.empty()){{$}}
+    if (0 >= s.size())
+      ;
+    // CHECK-MESSAGES: :[[@LINE-2]]:14: warning: the 'empty' method should be used to check for emptiness instead of 'size' [readability-container-size-empty]
+    // CHECK-FIXES: {{^    }}if (s.empty()){{$}}
+  }
+
+  void f(const SS& s) {
+    if (s.size() < 0) {}
+    if (0 > s.size()) {}
+    if (s.size() >= 0) {}
+    if (0 <= s.size()) {}
+    if (s.size() < 1) {}
+    if (1 > s.size()) {}
+    if (s.size() <= 0) {}
+    if (0 >= s.size()) {}
+  }
+}