[CI] Check that a second build has nothing to do - #23056
Draft
guitargeek wants to merge 3 commits into
Draft
Conversation
guitargeek
force-pushed
the
ci-null-build-check
branch
from
August 10, 2026 07:46
6287e1a to
3691cf4
Compare
Test Results 23 files 23 suites 3d 21h 48m 5s ⏱️ For more details on these failures, see this check. Results for commit 3691cf4. |
Building an already built tree twice in a row must be a no-op, apart from etc/gitinfo.txt which the gitinfotxt target rewrites on every build by design. When that is not the case, every incremental build pays for the targets that are needlessly redone plus everything depending on them. Add a null build check that runs on all platforms right after the build: it fingerprints every file in the build tree, builds again, and reports what was written. Doing it this way rather than parsing build tool output keeps it working across Ninja, Makefiles and MSBuild alike. The verdict is only acted on at the very end, after ctest, so that a spurious rebuild does not cost us the test results. 🤖 Done with the help of AI
GetPartiallyDesugaredTypeImpl removes the elaborated type keyword
('typename', 'struct', ...) of its input type: the keyword is pure
syntax and must never end up in a normalized type name. Since the
LLVM 22 migration removed ElaboratedType, the keyword lives on the
type node itself, and desugaring can expose a *new* one that nothing
strips. With
template <typename T> struct Container {
typedef typename std::vector<T*> seq_type;
seq_type m_sequential;
};
the keyword sits on the TemplateSpecializationType that seq_type
resolves to, so the normalized name of m_sequential came out as
'typename std::vector<Track*>'. TStreamerInfo::BuildOld then fails to
match it against the 'vector<Track*>' stored in the file, sets the new
type to -2 and skips the element, i.e. the member is silently not read.
The leak became visible with 081af22, which attaches the
reconstructed prefix to the TemplateSpecializationType; TypePrinter
prints the keyword whenever it is not None.
Only TemplateSpecializationType is affected; struct/enum elaborated
typedefs already normalize correctly.
Fixes root-project#23055
🤖 Done with the help of AI
ROOT_STANDARD_LIBRARY_PACKAGE(... NO_SOURCES) provided the dummy source file that add_library() needs as the output of a custom command that touches it. All the packages of one directory share that output, and listing one custom command output in several independent targets that build in parallel is not supported; core/clingutils alone has 15 of them. Ninja and Make happen to get away with it, but with MSBuild the touch runs again on every build, so 14 of the 15 STL dictionaries were recompiled and relinked every time, along with everything depending on them. Write the file at configure time instead. Nothing touches it at build time anymore, so it cannot go stale under the targets that compile it. 🤖 Done with the help of AI
guitargeek
force-pushed
the
ci-null-build-check
branch
from
August 10, 2026 14:16
3691cf4 to
8315dc9
Compare
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Building an already built tree twice in a row must be a no-op, apart from etc/gitinfo.txt which the gitinfotxt target rewrites on every build by design. When that is not the case, every incremental build pays for the targets that are needlessly redone plus everything depending on them.
Add a null build check that runs on all platforms right after the build: it fingerprints every file in the build tree, builds again, and reports what was written. Doing it this way rather than parsing build tool output keeps it working across Ninja, Makefiles and MSBuild alike.
The verdict is only acted on at the very end, after ctest, so that a spurious rebuild does not cost us the test results.
🤖 Done with the help of AI