[clang-tools-extra] a7520d9 - [Clang-tidy] bugprone-too-small-loop-variable - false-negative when const variable is used as loop bound (#81183)
via cfe-commits
cfe-commits at lists.llvm.org
Fri Feb 9 08:44:07 PST 2024
Author: Shourya Goel
Date: 2024-02-09T17:44:04+01:00
New Revision: a7520d9727d2638047e5c464b2937581f64e2ce5
URL: https://github.com/llvm/llvm-project/commit/a7520d9727d2638047e5c464b2937581f64e2ce5
DIFF: https://github.com/llvm/llvm-project/commit/a7520d9727d2638047e5c464b2937581f64e2ce5.diff
LOG: [Clang-tidy] bugprone-too-small-loop-variable - false-negative when const variable is used as loop bound (#81183)
Changed LibASTMatcher to give an appropriate warning
when a const loop bound is initialized with a function declaration.
Fixes: #79580
Added:
Modified:
clang-tools-extra/clang-tidy/bugprone/TooSmallLoopVariableCheck.cpp
clang-tools-extra/docs/ReleaseNotes.rst
clang-tools-extra/docs/clang-tidy/checks/bugprone/too-small-loop-variable.rst
clang-tools-extra/test/clang-tidy/checkers/bugprone/too-small-loop-variable.cpp
Removed:
################################################################################
diff --git a/clang-tools-extra/clang-tidy/bugprone/TooSmallLoopVariableCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/TooSmallLoopVariableCheck.cpp
index 8ba8b893e03a6f..a73d46f01d9b2d 100644
--- a/clang-tools-extra/clang-tidy/bugprone/TooSmallLoopVariableCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/TooSmallLoopVariableCheck.cpp
@@ -82,10 +82,14 @@ void TooSmallLoopVariableCheck::registerMatchers(MatchFinder *Finder) {
// We are interested in only those cases when the loop bound is a variable
// value (not const, enum, etc.).
StatementMatcher LoopBoundMatcher =
- expr(ignoringParenImpCasts(allOf(hasType(isInteger()),
- unless(integerLiteral()),
- unless(hasType(isConstQualified())),
- unless(hasType(enumType())))))
+ expr(ignoringParenImpCasts(allOf(
+ hasType(isInteger()), unless(integerLiteral()),
+ unless(allOf(
+ hasType(isConstQualified()),
+ declRefExpr(to(varDecl(anyOf(
+ hasInitializer(ignoringParenImpCasts(integerLiteral())),
+ isConstexpr(), isConstinit())))))),
+ unless(hasType(enumType())))))
.bind(LoopUpperBoundName);
// We use the loop increment expression only to make sure we found the right
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index e50914aed5f07a..dff8dd279940f8 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -117,6 +117,10 @@ Changes in existing checks
options `HeaderFileExtensions` and `ImplementationFileExtensions` by the
global options of the same name.
+- Improved :doc:`bugprone-too-small-loop-variable
+ <clang-tidy/checks/bugprone/too-small-loop-variable>` support by correctly
+ implementing the check for const loop boundary.
+
- Cleaned up :doc:`cppcoreguidelines-prefer-member-initializer
<clang-tidy/checks/cppcoreguidelines/prefer-member-initializer>`
by removing enforcement of rule `C.48
diff --git a/clang-tools-extra/docs/clang-tidy/checks/bugprone/too-small-loop-variable.rst b/clang-tools-extra/docs/clang-tidy/checks/bugprone/too-small-loop-variable.rst
index 0f45cc2fe11463..2c3ded952aa022 100644
--- a/clang-tools-extra/docs/clang-tidy/checks/bugprone/too-small-loop-variable.rst
+++ b/clang-tools-extra/docs/clang-tidy/checks/bugprone/too-small-loop-variable.rst
@@ -28,6 +28,10 @@ In a real use case size means a container's size which depends on the user input
This algorithm works for a small amount of objects, but will lead to freeze for
a larger user input.
+It's recommended to enable the compiler warning
+`-Wtautological-constant-out-of-range-compare` as well, since check does not
+inspect compile-time constant loop boundaries to avoid overlaps with the warning.
+
.. option:: MagnitudeBitsUpperLimit
Upper limit for the magnitude bits of the loop variable. If it's set the check
diff --git a/clang-tools-extra/test/clang-tidy/checkers/bugprone/too-small-loop-variable.cpp b/clang-tools-extra/test/clang-tidy/checkers/bugprone/too-small-loop-variable.cpp
index 3229deb93bada8..113150b168650b 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/bugprone/too-small-loop-variable.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/bugprone/too-small-loop-variable.cpp
@@ -93,6 +93,18 @@ void voidBadForLoopWithMacroBound() {
}
}
+unsigned int getVal() {
+ return 300;
+}
+
+// The iteration's upper bound has a function declaration.
+void voidBadForLoop8() {
+ const unsigned int l = getVal();
+ for (unsigned char i = 0; i < l; ++i) {
+ // CHECK-MESSAGES: :[[@LINE-1]]:29: warning: loop variable has narrower type 'unsigned char' than iteration's upper bound 'const unsigned int' [bugprone-too-small-loop-variable]
+ }
+}
+
////////////////////////////////////////////////////////////////////////////////
/// Correct loops: we should not warn here.
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