| Issue |
109450
|
| Summary |
`<QVariant>` causes big clang-tidy slowdown
|
| Labels |
clang-tidy,
performance
|
| Assignees |
|
| Reporter |
firewave
|
```cpp
#include <QVariant>
```
`.clang-tidy`
```yml
---
Checks: >
*,
-abseil-*,
-altera-*,
-android-*,
-boost-*,
-cert-*,
-cppcoreguidelines-*,
-darwin-*,
-fuchsia-*,
-google-*,
-hicpp-*,
-linuxkernel-*,
-llvm-*,
-llvmlibc-*,
-mpi-*,
-objc-*,
-openmp-*,
-zircon-*,
cert-err34-c,
cppcoreguidelines-pro-type-static-cast-downcast,
cppcoreguidelines-rvalue-reference-param-not-moved,
google-explicit-constructor,
-bugprone-assignment-in-if-condition,
-bugprone-branch-clone,
-bugprone-easily-swappable-parameters,
-bugprone-empty-catch,
-bugprone-macro-parentheses,
-bugprone-narrowing-conversions,
-bugprone-signed-char-misuse,
-bugprone-switch-missing-default-case,
-bugprone-unchecked-optional-access,
-clang-analyzer-*,
-concurrency-mt-unsafe,
-misc-const-correctness,
-misc-no-recursion,
-misc-non-private-member-variables-in-classes,
-misc-throw-by-value-catch-by-reference,
-misc-use-anonymous-namespace,
-modernize-avoid-c-arrays,
-modernize-deprecated-ios-base-aliases,
-misc-include-cleaner,
-misc-unused-using-decls,
-modernize-loop-convert,
-modernize-macro-to-enum,
-modernize-raw-string-literal,
-modernize-replace-auto-ptr,
-modernize-return-braced-init-list,
-modernize-type-traits,
-modernize-use-auto,
-modernize-use-designated-initializers,
-modernize-use-nodiscard,
-modernize-use-trailing-return-type,
-performance-avoid-endl,
-performance-inefficient-string-concatenation,
-performance-no-automatic-move,
-portability-simd-intrinsics,
-portability-std-allocator-const,
-readability-avoid-nested-conditional-operator,
-readability-braces-around-statements,
-readability-container-data-pointer,
-readability-enum-initial-value,
-readability-function-cognitive-complexity,
-readability-function-size,
-readability-identifier-length,
-readability-identifier-naming,
-readability-implicit-bool-conversion,
-readability-isolate-declaration,
-readability-magic-numbers,
-readability-suspicious-call-argument,
-readability-uppercase-literal-suffix
```
```
$ clang-tidy common.cpp --enable-check-profile -- $(pkg-config --cflags-only-I Qt6Core)
===-------------------------------------------------------------------------===
clang-tidy checks profiling
===-------------------------------------------------------------------------===
Total Execution Time: 20.2481 seconds (20.2487 wall clock)
```
It does not appear to be a single check:
```
---User Time--- --System Time-- --User+System-- ---Wall Time--- --- Name ---
0.2992 ( 4.3%) 0.6637 ( 5.0%) 0.9629 ( 4.8%) 0.9630 ( 4.8%) bugprone-stringview-nullptr
0.2908 ( 4.2%) 0.5689 ( 4.3%) 0.8597 ( 4.2%) 0.8546 ( 4.2%) bugprone-use-after-move
0.2382 ( 3.4%) 0.4826 ( 3.6%) 0.7208 ( 3.6%) 0.7190 ( 3.6%) bugprone-standalone-empty
0.2108 ( 3.0%) 0.4565 ( 3.4%) 0.6673 ( 3.3%) 0.6749 ( 3.3%) readability-non-const-parameter
0.1952 ( 2.8%) 0.4015 ( 3.0%) 0.5967 ( 2.9%) 0.5966 ( 2.9%) readability-container-size-empty
0.1794 ( 2.6%) 0.3919 ( 2.9%) 0.5713 ( 2.8%) 0.5736 ( 2.8%) readability-redundant-control-flow
0.1849 ( 2.7%) 0.3881 ( 2.9%) 0.5730 ( 2.8%) 0.5732 ( 2.8%) bugprone-unused-return-value
0.1779 ( 2.6%) 0.3838 ( 2.9%) 0.5617 ( 2.8%) 0.5650 ( 2.8%) bugprone-suspicious-string-compare
0.1769 ( 2.6%) 0.3742 ( 2.8%) 0.5511 ( 2.7%) 0.5504 ( 2.7%) bugprone-infinite-loop
0.1712 ( 2.5%) 0.3727 ( 2.8%) 0.5439 ( 2.7%) 0.5448 ( 2.7%) modernize-use-nullptr
0.1626 ( 2.3%) 0.3733 ( 2.8%) 0.5360 ( 2.6%) 0.5357 ( 2.6%) modernize-use-transparent-functors
0.1664 ( 2.4%) 0.3590 ( 2.7%) 0.5255 ( 2.6%) 0.5253 ( 2.6%) performance-move-const-arg
0.1655 ( 2.4%) 0.3583 ( 2.7%) 0.5238 ( 2.6%) 0.5241 ( 2.6%) bugprone-assert-side-effect
0.1624 ( 2.3%) 0.3531 ( 2.7%) 0.5155 ( 2.5%) 0.5158 ( 2.5%) bugprone-multiple-statement-macro
0.1613 ( 2.3%) 0.3512 ( 2.6%) 0.5124 ( 2.5%) 0.5126 ( 2.5%) bugprone-suspicious-semicolon
0.1561 ( 2.3%) 0.3383 ( 2.5%) 0.4944 ( 2.4%) 0.4948 ( 2.4%) bugprone-unused-raii
0.4487 ( 6.5%) 0.0238 ( 0.2%) 0.4725 ( 2.3%) 0.4725 ( 2.3%) bugprone-reserved-identifier
0.1431 ( 2.1%) 0.3162 ( 2.4%) 0.4593 ( 2.3%) 0.4589 ( 2.3%) bugprone-sizeof-_expression_
0.1439 ( 2.1%) 0.3134 ( 2.4%) 0.4573 ( 2.3%) 0.4575 ( 2.3%) bugprone-inc-dec-in-conditions
0.1391 ( 2.0%) 0.3045 ( 2.3%) 0.4436 ( 2.2%) 0.4448 ( 2.2%) bugprone-chained-comparison
0.1209 ( 1.7%) 0.2578 ( 1.9%) 0.3787 ( 1.9%) 0.3782 ( 1.9%) misc-confusable-identifiers
0.2194 ( 3.2%) 0.0992 ( 0.7%) 0.3186 ( 1.6%) 0.3181 ( 1.6%) modernize-use-using
0.0861 ( 1.2%) 0.1997 ( 1.5%) 0.2858 ( 1.4%) 0.2864 ( 1.4%) readability-redundant-declaration
[...]
```
`pkg-config` contains `-I` options for for includes and I manually modified them to `-isystem` but it does not make any difference.
There are other headers which are also quite slow (e.g. `<Qt>` and `<QFileInfo>` ) for just being included but they are not as bad as this one.
I can reproduce this with LLVM 18.1.8 and 19 using Qt 6.7.2. Unfortunately Qt6 is not available on the system I have all my older LLVM versions installed on so I cannot check when/if this is regressed.
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