hanchenye-llvm-project/clang/test/Modules/preprocess-missing.modulemap

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Support lazy stat'ing of files referenced by module maps. This patch adds support for a `header` declaration in a module map to specify certain `stat` information (currently, size and mtime) about that header file. This has two purposes: - It removes the need to eagerly `stat` every file referenced by a module map. Instead, we track a list of unresolved header files with each size / mtime (actually, for simplicity, we track submodules with such headers), and when attempting to look up a header file based on a `FileEntry`, we check if there are any unresolved header directives with that `FileEntry`'s size / mtime and perform deferred `stat`s if so. - It permits a preprocessed module to be compiled without the original files being present on disk. The only reason we used to need those files was to get the `stat` information in order to do header -> module lookups when using the module. If we're provided with the `stat` information in the preprocessed module, we can avoid requiring the files to exist. Unlike most `header` directives, if a `header` directive with `stat` information has no corresponding on-disk file the enclosing module is *not* marked unavailable (so that behavior is consistent regardless of whether we've resolved a header directive, and so that preprocessed modules don't get marked unavailable). We could actually do this for all `header` directives: the only reason we mark the module unavailable if headers are missing is to give a diagnostic slightly earlier (rather than waiting until we actually try to build the module / load and validate its .pcm file). Differential Revision: https://reviews.llvm.org/D33703 llvm-svn: 304515
2017-06-02 09:55:39 +08:00
// RUN: %clang_cc1 -fmodules -fmodule-name=A -x c++-module-map %s -emit-module -o /dev/null -verify
module A {
header "does not exist" { size 12345 } // ok, do not need mtime for explicit module build
header "also does not exist" { mtime 12345 }
}
#pragma clang module contents
// expected-error@4 {{cannot emit module A: size must be explicitly specified for missing header file "also does not exist"}}