Target triple adjustment on Mac OS X when using clang cc1 to execute the analyzer with CTU enabled

The problem is detected in the test case of D102669 and D75665.
It is not the problem of the static analyzer, but the frontend driver and cc1 compiler.

When executing the test case of the static analyzer, we usually use %clang_analyze_cc1 as the entry, which is %clang_cc1 -analyze. And we usually do not set a target triple, as it is not required by the analyzer. However, things are complicated in Darwin Unix.

In Darwin, the default target triple is ARCH-apple-darwinXX.XX.XX, where ARCH is the architecture (e.g. x86_64) and XX.XX.XX is the version of the Darwin system. And the default target triple will be then adjusted to ARCH-apple-SYSTEMXX.XX.XX by the Driver::Darwin::ComputeEffectiveClangTriple in driver related code, where SYSTEM can be watchos, tvos, ios and macosx.

In the clang driver, the adjusted target triple will be passed to the new cc1 process; whereas in tooling and ASTUnit::LoadFromCommandLine, the adjusted target triple will be used to generate cc1 arguments to create CompilerInvocation. But when executing bare clang -cc1, if the target triple argument is not provided, it remains the default ARCH-apple-darwinXX.XX.XX. And this is the reason for the conflict.

The CTU on-demand-parsing mechanism uses ASTUnit::LoadFromCommandLine to load external ASTs. The tool clang-check uses clang tooling to parse the entry file. Therefore, both target triples are the adjusted ones, which can be matched. And so is the driver (clang --analyze ...). But not the bare %clang_cc1, its target triple is the default one.

Let’s have a look at the simple example, suppose externalDefMap.txt and invocations.yaml are generated correctly.

void bar();
void foo() { bar(); }

void bar() { }

Using driver:

clang -v --analyze -Xanalyzer -analyzer-config -Xanalyzer experimental-enable-naive-ctu-analysis=true,ctu-dir=.

Output: OK, adjusted to adjusted

/path/to/clang-15 -cc1 -triple x86_64-apple-macosx10.15.0 ...

Using clang-check:

clang-check -analyze -- -v -Xanalyzer -analyzer-config -Xanalyzer experimental-enable-naive-ctu-analysis=true,ctu-dir=.

Output: OK, adjusted to adjusted

clang Invocation:
 "/path/to/clang-tool" "-cc1" "-triple" "x86_64-apple-macosx10.15.0"

Using cc1:

clang -cc1 -v -analyze  -analyzer-checker=core -analyzer-config experimental-enable-naive-ctu-analysis=true,ctu-dir=.

Output: ERROR, default to adjusted

warning: imported AST from '' had been generated for a different target, current: x86_64-apple-darwin19.6.0, imported: x86_64-apple-macosx10.15.0 [-Wctu]

What is a better way to fix this problem?
Using clang-check to run the test case seems to be a good way to overcome the problem, but the problem still exists.
However, IMO it is not a good idea to make clang cc1 to adjust the default target triple manually.