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
diff --git a/clang/lib/Frontend/FrontendAction.cpp b/clang/lib/Frontend/FrontendAction.cpp
index cd67e46..e2fbe96 100644
--- a/clang/lib/Frontend/FrontendAction.cpp
+++ b/clang/lib/Frontend/FrontendAction.cpp
@@ -289,14 +289,28 @@
///
/// \param Includes Will be augmented with the set of \#includes or \#imports
/// needed to load all of the named headers.
-static std::error_code
-collectModuleHeaderIncludes(const LangOptions &LangOpts, FileManager &FileMgr,
- ModuleMap &ModMap, clang::Module *Module,
- SmallVectorImpl<char> &Includes) {
+static std::error_code collectModuleHeaderIncludes(
+ const LangOptions &LangOpts, FileManager &FileMgr, DiagnosticsEngine &Diag,
+ ModuleMap &ModMap, clang::Module *Module, SmallVectorImpl<char> &Includes) {
// Don't collect any headers for unavailable modules.
if (!Module->isAvailable())
return std::error_code();
+ // Resolve all lazy header directives to header files.
+ ModMap.resolveHeaderDirectives(Module);
+
+ // If any headers are missing, we can't build this module. In most cases,
+ // diagnostics for this should have already been produced; we only get here
+ // if explicit stat information was provided.
+ // FIXME: If the name resolves to a file with different stat information,
+ // produce a better diagnostic.
+ if (!Module->MissingHeaders.empty()) {
+ auto &MissingHeader = Module->MissingHeaders.front();
+ Diag.Report(MissingHeader.FileNameLoc, diag::err_module_header_missing)
+ << MissingHeader.IsUmbrella << MissingHeader.FileName;
+ return std::error_code();
+ }
+
// Add includes for each of these headers.
for (auto HK : {Module::HK_Normal, Module::HK_Private}) {
for (Module::Header &H : Module->Headers[HK]) {
@@ -367,7 +381,7 @@
SubEnd = Module->submodule_end();
Sub != SubEnd; ++Sub)
if (std::error_code Err = collectModuleHeaderIncludes(
- LangOpts, FileMgr, ModMap, *Sub, Includes))
+ LangOpts, FileMgr, Diag, ModMap, *Sub, Includes))
return Err;
return std::error_code();
@@ -494,7 +508,7 @@
addHeaderInclude(UmbrellaHeader.NameAsWritten, HeaderContents,
CI.getLangOpts(), M->IsExternC);
Err = collectModuleHeaderIncludes(
- CI.getLangOpts(), FileMgr,
+ CI.getLangOpts(), FileMgr, CI.getDiagnostics(),
CI.getPreprocessor().getHeaderSearchInfo().getModuleMap(), M,
HeaderContents);