[clang-tools-extra] [clang-tidy] Invalid Fix-It generated for implicit-widening-multiplication-result (PR #76315)
Félix-Antoine Constantin via cfe-commits
cfe-commits at lists.llvm.org
Sat Dec 23 20:33:18 PST 2023
https://github.com/felix642 created https://github.com/llvm/llvm-project/pull/76315
The check currently emits warnings for the following code:
`uint64_t fn() { return 1024 * 1024; }`
But the code generated after applying the notes will look like this:
`uint64_t fn() { return static_cast<uint64_t>(1024 * )1024; }`
```
[<source>:5:12: warning: performing an implicit widening conversion to type 'uint64_t' (aka 'unsigned long') of a multiplication performed in type 'int' [bugprone-implicit-widening-of-multiplication-result]](javascript:;)
5 | return 1024 * 1024;
| ^
[<source>:5:12: note: make conversion explicit to silence this warning](javascript:;)
1 | #include <cstdint>
2 |
3 | uint64_t fn()
4 | {
5 | return 1024 * 1024;
| ^~~~~~~~~~~
| static_cast<uint64_t>( )
[<source>:5:12: note: perform multiplication in a wider type](javascript:;)
5 | return 1024 * 1024;
| ^~~~
| static_cast<long>()
1 warning generated.
```
This is because when generating the notes the check will use the beginLoc() and EndLoc() of the subexpr of the implicit cast.
But in some cases the AST Node might not have a beginLoc and EndLoc. This seems to be true when the Node is composed of only 1 token (for example an integer literal). Calling the getEndLoc() on this type of node will simply return the known location which is, in this case, the beginLoc.
Fixes #63070 #56728
I was not able to add tests for this commit and this is because the check currently emits two notes for every detection.
The first suggestion is to silence the warning by casting the whole operation.
The second suggestion is there to fix the issue (And I think the suggested code is invalid, but I've opened another issue for that: https://github.com/llvm/llvm-project/issues/76311).
Since both suggestions are overlapping clang-tidy refuses to apply them and I was not able to add new tests.
The first suggestion seems useless since we should not suggest a fix-it to silence an issue (the message seems sufficient to me).
But this requires more discussion and the change is not trivial so I've left it how it is for now.
>From 7d9c4d423c00033e8c4df26b87176e3054976423 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?F=C3=A9lix-Antoine=20Constantin?=
<felix-antoine.constantin at polymtl.ca>
Date: Sat, 23 Dec 2023 23:17:03 -0500
Subject: [PATCH] =?UTF-8?q?[clang-tidy]=C2=A0Invalid=20Fix-It=20generated?=
=?UTF-8?q?=20for=20implicit-widening-multiplication-result?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
The check currently emits warnings for the following code:
uint64_t fn() { return 1024 * 1024; }
But the code generated after applying the notes will look like this:
uint64_t fn() { return static_cast<uint64_t>(1024 * )1024; }
This is because when generating the notes the check will use the beginLoc
and EndLoc of the subexpr of the implicit cast.
But in some cases the AST Node might not have a beginLoc and EndLoc. This
seems to be true when the Node is composed of only 1 token (for example
an integer literal). Calling the getEndLoc() on this type of node will
simply return the known location which is, in this case, the beginLoc.
Fixes #63070 #56728
---
...citWideningOfMultiplicationResultCheck.cpp | 27 +++++++++++++------
clang-tools-extra/docs/ReleaseNotes.rst | 4 +++
...tion-result-array-subscript-expression.cpp | 4 +--
...-widening-of-multiplication-result-int.cpp | 8 +++---
...f-multiplication-result-pointer-offset.cpp | 4 +--
5 files changed, 31 insertions(+), 16 deletions(-)
diff --git a/clang-tools-extra/clang-tidy/bugprone/ImplicitWideningOfMultiplicationResultCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/ImplicitWideningOfMultiplicationResultCheck.cpp
index 95a7c521eabb0e..6f22f02f301835 100644
--- a/clang-tools-extra/clang-tidy/bugprone/ImplicitWideningOfMultiplicationResultCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/ImplicitWideningOfMultiplicationResultCheck.cpp
@@ -9,6 +9,7 @@
#include "ImplicitWideningOfMultiplicationResultCheck.h"
#include "clang/AST/ASTContext.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/Lex/Lexer.h"
#include <optional>
using namespace clang::ast_matchers;
@@ -99,15 +100,16 @@ void ImplicitWideningOfMultiplicationResultCheck::handleImplicitCastExpr(
"make conversion explicit to silence this warning",
DiagnosticIDs::Note)
<< E->getSourceRange();
-
+ const SourceLocation EndLoc = Lexer::getLocForEndOfToken(
+ E->getEndLoc(), 0, *Result->SourceManager, getLangOpts());
if (ShouldUseCXXStaticCast)
Diag << FixItHint::CreateInsertion(
E->getBeginLoc(), "static_cast<" + Ty.getAsString() + ">(")
- << FixItHint::CreateInsertion(E->getEndLoc(), ")");
+ << FixItHint::CreateInsertion(EndLoc, ")");
else
Diag << FixItHint::CreateInsertion(E->getBeginLoc(),
"(" + Ty.getAsString() + ")(")
- << FixItHint::CreateInsertion(E->getEndLoc(), ")");
+ << FixItHint::CreateInsertion(EndLoc, ")");
Diag << includeStddefHeader(E->getBeginLoc());
}
@@ -137,7 +139,11 @@ void ImplicitWideningOfMultiplicationResultCheck::handleImplicitCastExpr(
Diag << FixItHint::CreateInsertion(LHS->getBeginLoc(),
"static_cast<" +
WideExprTy.getAsString() + ">(")
- << FixItHint::CreateInsertion(LHS->getEndLoc(), ")");
+ << FixItHint::CreateInsertion(
+ Lexer::getLocForEndOfToken(LHS->getEndLoc(), 0,
+ *Result->SourceManager,
+ getLangOpts()),
+ ")");
else
Diag << FixItHint::CreateInsertion(LHS->getBeginLoc(),
"(" + WideExprTy.getAsString() + ")");
@@ -206,16 +212,17 @@ void ImplicitWideningOfMultiplicationResultCheck::handlePointerOffsetting(
"make conversion explicit to silence this warning",
DiagnosticIDs::Note)
<< IndexExpr->getSourceRange();
-
+ const SourceLocation EndLoc = Lexer::getLocForEndOfToken(
+ IndexExpr->getEndLoc(), 0, *Result->SourceManager, getLangOpts());
if (ShouldUseCXXStaticCast)
Diag << FixItHint::CreateInsertion(
IndexExpr->getBeginLoc(),
(Twine("static_cast<") + TyAsString + ">(").str())
- << FixItHint::CreateInsertion(IndexExpr->getEndLoc(), ")");
+ << FixItHint::CreateInsertion(EndLoc, ")");
else
Diag << FixItHint::CreateInsertion(IndexExpr->getBeginLoc(),
(Twine("(") + TyAsString + ")(").str())
- << FixItHint::CreateInsertion(IndexExpr->getEndLoc(), ")");
+ << FixItHint::CreateInsertion(EndLoc, ")");
Diag << includeStddefHeader(IndexExpr->getBeginLoc());
}
@@ -229,7 +236,11 @@ void ImplicitWideningOfMultiplicationResultCheck::handlePointerOffsetting(
Diag << FixItHint::CreateInsertion(
LHS->getBeginLoc(),
(Twine("static_cast<") + TyAsString + ">(").str())
- << FixItHint::CreateInsertion(LHS->getEndLoc(), ")");
+ << FixItHint::CreateInsertion(
+ Lexer::getLocForEndOfToken(IndexExpr->getEndLoc(), 0,
+ *Result->SourceManager,
+ getLangOpts()),
+ ")");
else
Diag << FixItHint::CreateInsertion(LHS->getBeginLoc(),
(Twine("(") + TyAsString + ")").str());
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index 6d5f49dc062545..55fba7d86468d0 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -222,6 +222,10 @@ Changes in existing checks
casting during type conversions at variable initialization, now with improved
compatibility for C++17 and later versions.
+- Improved :doc:`bugprone-implicit-widening-of-multiplication-result
+ <clang-tidy/checks/bugprone/implicit-widening-of-multiplication-result>` check
+ to correctly emit fixes.
+
- Improved :doc:`bugprone-lambda-function-name
<clang-tidy/checks/bugprone/lambda-function-name>` check by adding option
`IgnoreMacros` to ignore warnings in macros.
diff --git a/clang-tools-extra/test/clang-tidy/checkers/bugprone/implicit-widening-of-multiplication-result-array-subscript-expression.cpp b/clang-tools-extra/test/clang-tidy/checkers/bugprone/implicit-widening-of-multiplication-result-array-subscript-expression.cpp
index 2881341c878570..5b432cb2662968 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/bugprone/implicit-widening-of-multiplication-result-array-subscript-expression.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/bugprone/implicit-widening-of-multiplication-result-array-subscript-expression.cpp
@@ -18,7 +18,7 @@ char *t0(char *base, int a, int b) {
// CHECK-NOTES-CXX: static_cast<ptrdiff_t>( )
// CHECK-NOTES-ALL: :[[@LINE-5]]:16: note: perform multiplication in a wider type
// CHECK-NOTES-C: (ptrdiff_t)
- // CHECK-NOTES-CXX: static_cast<ptrdiff_t>()
+ // CHECK-NOTES-CXX: static_cast<ptrdiff_t>( )
}
void *t1(char *base, int a, int b) {
return &((a * b)[base]);
@@ -35,7 +35,7 @@ char *t2(char *base, unsigned int a, int b) {
// CHECK-NOTES-CXX: static_cast<size_t>( )
// CHECK-NOTES-ALL: :[[@LINE-5]]:16: note: perform multiplication in a wider type
// CHECK-NOTES-C: (size_t)
- // CHECK-NOTES-CXX: static_cast<size_t>()
+ // CHECK-NOTES-CXX: static_cast<size_t>( )
}
char *t3(char *base, int a, unsigned int b) {
diff --git a/clang-tools-extra/test/clang-tidy/checkers/bugprone/implicit-widening-of-multiplication-result-int.cpp b/clang-tools-extra/test/clang-tidy/checkers/bugprone/implicit-widening-of-multiplication-result-int.cpp
index cf13a7ea9fbd8b..8619a4ee86550a 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/bugprone/implicit-widening-of-multiplication-result-int.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/bugprone/implicit-widening-of-multiplication-result-int.cpp
@@ -18,7 +18,7 @@ long t0(int a, int b) {
// CHECK-NOTES-CXX: static_cast<long>( )
// CHECK-NOTES-ALL: :[[@LINE-5]]:10: note: perform multiplication in a wider type
// CHECK-NOTES-C: (long)
- // CHECK-NOTES-CXX: static_cast<long>()
+ // CHECK-NOTES-CXX: static_cast<long>( )
}
unsigned long t1(int a, int b) {
return a * b;
@@ -28,7 +28,7 @@ unsigned long t1(int a, int b) {
// CHECK-NOTES-CXX: static_cast<unsigned long>( )
// CHECK-NOTES-ALL: :[[@LINE-5]]:10: note: perform multiplication in a wider type
// CHECK-NOTES-C: (long)
- // CHECK-NOTES-CXX: static_cast<long>()
+ // CHECK-NOTES-CXX: static_cast<long>( )
}
long t2(unsigned int a, int b) {
@@ -39,7 +39,7 @@ long t2(unsigned int a, int b) {
// CHECK-NOTES-CXX: static_cast<long>( )
// CHECK-NOTES-ALL: :[[@LINE-5]]:10: note: perform multiplication in a wider type
// CHECK-NOTES-C: (unsigned long)
- // CHECK-NOTES-CXX: static_cast<unsigned long>()
+ // CHECK-NOTES-CXX: static_cast<unsigned long>( )
}
unsigned long t3(unsigned int a, int b) {
return a * b;
@@ -49,7 +49,7 @@ unsigned long t3(unsigned int a, int b) {
// CHECK-NOTES-CXX: static_cast<unsigned long>( )
// CHECK-NOTES-ALL: :[[@LINE-5]]:10: note: perform multiplication in a wider type
// CHECK-NOTES-C: (unsigned long)
- // CHECK-NOTES-CXX: static_cast<unsigned long>()
+ // CHECK-NOTES-CXX: static_cast<unsigned long>( )
}
long t4(int a, unsigned int b) {
diff --git a/clang-tools-extra/test/clang-tidy/checkers/bugprone/implicit-widening-of-multiplication-result-pointer-offset.cpp b/clang-tools-extra/test/clang-tidy/checkers/bugprone/implicit-widening-of-multiplication-result-pointer-offset.cpp
index c812885507e8f3..5ba6a5639849df 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/bugprone/implicit-widening-of-multiplication-result-pointer-offset.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/bugprone/implicit-widening-of-multiplication-result-pointer-offset.cpp
@@ -18,7 +18,7 @@ char *t0(char *base, int a, int b) {
// CHECK-NOTES-CXX: static_cast<ptrdiff_t>( )
// CHECK-NOTES-ALL: :[[@LINE-5]]:17: note: perform multiplication in a wider type
// CHECK-NOTES-C: (ptrdiff_t)
- // CHECK-NOTES-CXX: static_cast<ptrdiff_t>()
+ // CHECK-NOTES-CXX: static_cast<ptrdiff_t>( )
}
char *t1(char *base, int a, int b) {
return a * b + base;
@@ -35,7 +35,7 @@ char *t2(char *base, unsigned int a, int b) {
// CHECK-NOTES-CXX: static_cast<size_t>( )
// CHECK-NOTES-ALL: :[[@LINE-5]]:17: note: perform multiplication in a wider type
// CHECK-NOTES-C: (size_t)
- // CHECK-NOTES-CXX: static_cast<size_t>()
+ // CHECK-NOTES-CXX: static_cast<size_t>( )
}
char *t3(char *base, int a, unsigned int b) {
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