Commit Graph

2360 Commits

Author SHA1 Message Date
Duncan P. N. Exon Smith d10f9863a5 ADT: Migrate users of AlignedCharArrayUnion to std::aligned_union_t, NFC
Prepare to delete `AlignedCharArrayUnion` by migrating its users over to
`std::aligned_union_t`.

I will delete `AlignedCharArrayUnion` and its tests in a follow-up
commit so that it's easier to revert in isolation in case some
downstream wants to keep using it.

Differential Revision: https://reviews.llvm.org/D92516
2020-12-04 12:34:49 -08:00
Duncan P. N. Exon Smith 32c501dd88 Module: Use FileEntryRef and DirectoryEntryRef in Umbrella, Header, and DirectoryName, NFC
Push `FileEntryRef` and `DirectoryEntryRef` further, using it them
`Module::Umbrella`, `Module::Header::Entry`, and
`Module::DirectoryName::Entry`.

- Add `DirectoryEntryRef::operator const DirectoryEntry *` and
  `OptionalDirectoryEntryRefDegradesToDirectoryEntryPtr`, to get the
  same "degrades to `DirectoryEntry*` behaviour `FileEntryRef` enjoys
  (this avoids a bunch of churn in various clang tools).
- Fix the `DirectoryEntryRef` constructor from `MapEntry` to take it by
  `const&`.

Note that we cannot get rid of the `...AsWritten` names leveraging the
new classes, since these need to be as written in the `ModuleMap` file
and the module directory path is preprended for the lookup in the
`FileManager`.

Differential Revision: https://reviews.llvm.org/D90497
2020-12-02 14:07:23 -08:00
Duncan P. N. Exon Smith f85db7f7ba Lex: Update Module::findHeader to return FileEntryRef, NFC
Update `Module::findHeader` to return `Optional<FileEntryRef>` and
fix its one caller.

Differential Revision: https://reviews.llvm.org/D90485
2020-11-30 17:13:03 -08:00
Alexandre Rames 58c586e701 Allow searching for prebuilt implicit modules.
This reverts commit c67656b994, and addresses the
build issue.
2020-11-10 10:14:13 -08:00
Stella Stamenova c67656b994 Revert "Allow searching for prebuilt implicit modules."
This reverts commit 71e108cd86.

This change caused a build failure on Windows:
http://lab.llvm.org:8011/#/builders/83/builds/570
2020-11-05 17:16:14 -08:00
Alexandre Rames 71e108cd86 Allow searching for prebuilt implicit modules.
The behavior is controlled by the `-fprebuilt-implicit-modules` option, and
allows searching for implicit modules in the prebuilt module cache paths.

The current command-line options for prebuilt modules do not allow to easily
maintain and use multiple versions of modules. Both the producer and users of
prebuilt modules are required to know the relationships between compilation
options and module file paths. Using a particular version of a prebuilt module
requires passing a particular option on the command line (e.g.
`-fmodule-file=[<name>=]<file>` or `-fprebuilt-module-path=<directory>`).

However the compiler already knows how to distinguish and automatically locate
implicit modules. Hence this proposal to introduce the
`-fprebuilt-implicit-modules` option. When set, it enables searching for
implicit modules in the prebuilt module paths (specified via
`-fprebuilt-module-path`). To not modify existing behavior, this search takes
place after the standard search for prebuilt modules. If not

Here is a workflow illustrating how both the producer and consumer of prebuilt
modules would need to know what versions of prebuilt modules are available and
where they are located.

  clang -cc1 -x c modulemap -fmodules -emit-module -fmodule-name=foo -fmodules-cache-path=prebuilt_modules_v1 <config 1 options>
  clang -cc1 -x c modulemap -fmodules -emit-module -fmodule-name=foo -fmodules-cache-path=prebuilt_modules_v2 <config 2 options>
  clang -cc1 -x c modulemap -fmodules -emit-module -fmodule-name=foo -fmodules-cache-path=prebuilt_modules_v3 <config 3 options>

  clang -cc1 -x c use.c -fmodules fmodule-map-file=modulemap -fprebuilt-module-path=prebuilt_modules_v1 <config 1 options>
  clang -cc1 -x c use.c -fmodules fmodule-map-file=modulemap <non-prebuilt config options>

With prebuilt implicit modules, the producer can generate prebuilt modules as
usual, all in the same output directory. The same mechanisms as for implicit
modules take care of incorporating hashes in the path to distinguish between
module versions.

Note that we do not specify the output module filename, so `-o` implicit modules are generated in the cache path `prebuilt_modules`.

  clang -cc1 -x c modulemap -fmodules -emit-module -fmodule-name=foo -fmodules-cache-path=prebuilt_modules <config 1 options>
  clang -cc1 -x c modulemap -fmodules -emit-module -fmodule-name=foo -fmodules-cache-path=prebuilt_modules <config 2 options>
  clang -cc1 -x c modulemap -fmodules -emit-module -fmodule-name=foo -fmodules-cache-path=prebuilt_modules <config 3 options>

The user can now simply enable prebuilt implicit modules and point to the
prebuilt modules cache. No need to "parse" command-line options to decide
what prebuilt modules (paths) to use.

  clang -cc1 -x c use.c -fmodules fmodule-map-file=modulemap -fprebuilt-module-path=prebuilt_modules -fprebuilt-implicit-modules <config 1 options>
  clang -cc1 -x c use.c -fmodules fmodule-map-file=modulemap -fprebuilt-module-path=prebuilt_modules -fprebuilt-implicit-modules <non-prebuilt config options>

This is for example particularly useful in a use-case where compilation is
expensive, and the configurations expected to be used are predictable, but not
controlled by the producer of prebuilt modules. Modules for the set of
predictable configurations can be prebuilt, and using them does not require
"parsing" the configuration (command-line options).

Reviewed By: Bigcheese

Differential Revision: https://reviews.llvm.org/D68997
2020-11-05 13:10:53 -08:00
Duncan P. N. Exon Smith 6e73cfa836 Basic: Change Module::Umbrella to a PointerUnion, NFC
Change `Module::Umbrella` from a `const void *` to a `PointerUnion` of
`FileEntry` and `DirectoryEntry`. We can drop the `HasUmbrellaDir` bit
(since `PointerUnion` includes that).

This change makes it safer to update to `FileEntryRef` and
`DirectoryEntryRef` in a future patch.

Differential Revision: https://reviews.llvm.org/D90481
2020-11-04 16:19:39 -05:00
Duncan P. N. Exon Smith 74910cbbd8 HeaderSearch: Simplify use of FileEntryRef in HeaderSearch::LookupFile, NFC
Simplify `HeaderSearch::LookupFile`. Instead of deconstructing a
`FileEntryRef` into a name and `FileEntry` and then rebuilding it later,
use it as is. This helps to unblock making the constructor of
`FileEntryRef` private to `FileManager`.

Differential Revision:
2020-10-23 22:10:50 -04:00
Duncan P. N. Exon Smith 5431c37b55 SourceManager: Make LastLineNoContentCache and ContentCache::SourceLineCache mutable, NFC
Avoid some noisy `const_cast`s by making `ContentCache::SourceLineCache`
and `SourceManager::LastLineNoContentCache` both mutable.

Differential Revision: https://reviews.llvm.org/D89914
2020-10-23 13:22:47 -04:00
Duncan P. N. Exon Smith dbbc4f4e22 SourceManager: Encapsulate line number mapping into SrcMgr::LineOffsetMapping
Put the guts of `ComputeLineNumbers` into `LineOffsetMapping::get` and
`LineOffsetMapping::LineOffsetMapping`.  As a drive-by, store the number
of lines directly in the bump-ptr-allocated array.

Differential Revision: https://reviews.llvm.org/D89913
2020-10-23 12:55:51 -04:00
Duncan P. N. Exon Smith 74a8783480 SourceManager: Clarify that FileInfo always has a ContentCache, NFC
It turns out that `FileInfo` *always* has a ContentCache. Clarify that
in the code:
- Update the private version of `SourceManager::createFileID` to take a
  `ContentCache&` instead of `ContentCache*`, and rename it to
  `createFileIDImpl` for clarity.
- Change `FileInfo::getContentCache` to return a reference.

Differential Revision: https://reviews.llvm.org/D89554
2020-10-23 12:38:53 -04:00
Duncan P. N. Exon Smith 168db92465 SourceManager: Change SourceManager::isMainFile to take a FileEntry, NFC
`SourceManager::isMainFile` does not use the filename, so it doesn't
need the full `FileEntryRef`; in fact, it's misleading to take the name
because that makes it look relevant. Simplify the API, and in the
process remove some calls to `FileEntryRef::FileEntryRef` in the unit
tests (which were blocking making that private to `SourceManager`).

Differential Revision: https://reviews.llvm.org/D89507
2020-10-22 21:32:28 -04:00
Duncan P. N. Exon Smith 2dc7e0c6a5 clang/Basic: Replace SourceManager::getMemoryBufferForFile, NFC
Replace `SourceManager::getMemoryBufferForFile`, which returned a
dereferenceable `MemoryBuffer*` and had a `bool*Invalid` out parameter,
with `getMemoryBufferForFileOrNone` (returning
`Optional<MemoryBufferRef>`) and `getMemoryBufferForFileOrFake`
(returning `MemoryBufferRef`).

Differential Revision: https://reviews.llvm.org/D89429
2020-10-20 17:01:23 -04:00
Duncan P. N. Exon Smith b03ae74319 clang/Lex: Stop using SourceManager::getBuffer
Update clang/lib/Lex to stop relying on a `MemoryBuffer*`, using the
`MemoryBufferRef` from `getBufferOrNone` since both locations had logic
for checking validity of the buffer. There's potentially a functionality
change, since the logic was wrong (it checked for `nullptr`, which was
never returned by the old API), but if that was reachable the new
behaviour should be better.

Differential Revision: https://reviews.llvm.org/D89402
2020-10-19 20:27:56 -04:00
Duncan P. N. Exon Smith b3eff6b7bb Lexer: Update the Lexer to use MemoryBufferRef, NFC
Update `Lexer` / `Lexer::Lexer` to use `MemoryBufferRef` instead of
`MemoryBuffer*`. Callers that were acquiring a `MemoryBuffer*` via
`SourceManager::getBuffer` were updated, such that if they checked
`Invalid` they use `getBufferOrNone` and otherwise `getBufferOrFake`.

Differential Revision: https://reviews.llvm.org/D89398
2020-10-19 19:10:21 -04:00
Duncan P. N. Exon Smith 69feac12d0 Lex: Avoid MemoryBuffer* key in ExcludedPreprocessorDirectiveSkipMapping, NFC
This is a prep patch for changing SourceManager to return
`Optional<MemoryBufferRef>` instead of `MemoryBuffer`. With that change the
address of the MemoryBuffer will be gone, so instead use the start of the
buffer as the key for this map.

No functionality change intended, as it's expected that the pointer identity
matches between the buffers and the buffer data.

Radar-Id: rdar://70139990
Differential Revision: https://reviews.llvm.org/D89136
2020-10-12 17:39:01 -04:00
Chuyang Chen 8fa45e1fd5 Convert diagnostics about multi-character literals from extension to warning
This addresses PR46797.
2020-10-06 08:47:17 -04:00
Zequan Wu 9caa3fbe03 [Coverage] Add empty line regions to SkippedRegions
Differential Revision: https://reviews.llvm.org/D84988
2020-09-21 12:42:53 -07:00
Zixu Wang ed79827aea [clang][module] Improve incomplete-umbrella warning
Change the warning message for -Wincomplete-umbrella to report the location of the umbrella header;

Differential Revision: https://reviews.llvm.org/D82118
2020-09-18 14:56:47 -07:00
Simon Pilgrim 48b510c4bc [NFC] Fix compiler warnings due to integer comparison of different signedness
Fix by directly using INT_MAX and INT32_MAX.

Patch by: @nullptr.cpp (Yang Fan)

Differential Revision: https://reviews.llvm.org/D87347
2020-09-11 15:32:03 +01:00
Nick Desaulniers 663f4f7edc [clang] consistently use getLangOpts()
File was inconsistent.
2020-09-01 15:56:53 -07:00
Volodymyr Sapsai 8839e278ff [Modules] Improve error message when cannot find parent module for submodule definition.
Before the change the diagnostic for

    module unknown.submodule {}

was "error: expected module name" which is incorrect and misleading
because both "unknown" and "submodule" are valid module names.

We already have a better error message when a parent module is a
submodule itself and is missing. Make the error for a missing top-level
module more like the one for a submodule.

rdar://problem/64424407

Reviewed By: bruno

Differential Revision: https://reviews.llvm.org/D84458
2020-08-25 16:31:27 -07:00
Volodymyr Sapsai 7ac737e56b [HeaderSearch] Fix processing #import-ed headers multiple times with modules enabled.
HeaderSearch was marking requested HeaderFileInfo as Resolved only based on
the presence of ExternalSource. As the result, using any module was enough
to set ExternalSource and headers unknown to this module would have
HeaderFileInfo with empty fields, including `isImport = 0`, `NumIncludes = 0`.
Such HeaderFileInfo was preserved without changes regardless of how the
header was used in other modules and caused incorrect result in
`HeaderSearch::ShouldEnterIncludeFile`.

Fix by marking HeaderFileInfo as Resolved only if ExternalSource knows
about this header.

rdar://problem/62126911

Reviewed By: bruno

Differential Revision: https://reviews.llvm.org/D80263
2020-08-20 17:41:28 -07:00
Anastasia Stulova 3c8a4ee076 [OpenCL] Remove warning for variadic macros in C++ for OpenCL.
Patch by Ole Strohm (olestrohm)!

Tags: #clang

Differential Revision: https://reviews.llvm.org/D85429
2020-08-12 16:17:54 +01:00
Zequan Wu b46176bbb0 Reland [Coverage] Add comment to skipped regions
Bug filled here: https://bugs.llvm.org/show_bug.cgi?id=45757.
Add comment to skipped regions so we don't track execution count for lines containing only comments.

Differential Revision: https://reviews.llvm.org/D83592
2020-07-28 13:20:57 -07:00
Hans Wennborg 238bbd48c5 Revert abd45154b "[Coverage] Add comment to skipped regions"
This casued assertions during Chromium builds. See comment on the code review

> Bug filled here: https://bugs.llvm.org/show_bug.cgi?id=45757.
> Add comment to skipped regions so we don't track execution count for lines containing only comments.
>
> Differential Revision: https://reviews.llvm.org/D84208

This reverts commit abd45154bd and the
follow-up 87d7254733.
2020-07-22 17:09:20 +02:00
Zequan Wu abd45154bd [Coverage] Add comment to skipped regions
Bug filled here: https://bugs.llvm.org/show_bug.cgi?id=45757.
Add comment to skipped regions so we don't track execution count for lines containing only comments.

Differential Revision: https://reviews.llvm.org/D84208
2020-07-21 17:34:18 -07:00
Zequan Wu dcd76c0c07 [Lexer] Fix missing coverage line after #endif
Summary: bug reported here: https://bugs.llvm.org/show_bug.cgi?id=46660

Reviewers: vsk, efriedma, arphaman

Reviewed By: vsk

Subscribers: dexonsmith, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D83514
2020-07-10 09:05:20 -07:00
Zequan Wu 8be204fe75 Revert "[Lexer] Fix missing coverage line after #endif"
This reverts commit 672ae621e9.
2020-07-09 15:51:02 -07:00
Zequan Wu 672ae621e9 [Lexer] Fix missing coverage line after #endif
Summary: bug reported here: https://bugs.llvm.org/show_bug.cgi?id=46660

Reviewers: vsk, efriedma, arphaman

Reviewed By: vsk

Subscribers: dexonsmith, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D83514
2020-07-09 15:15:40 -07:00
Dmitri Gribenko 3cca818efa Refactored NumericLiteralParser to not require a Preprocessor
Summary:
We would like to use NumericLiteralParser in the implementation of the
syntax tree builder, and plumbing a preprocessor there seems
inconvenient and superfluous.

Reviewers: eduucaldas

Reviewed By: eduucaldas

Subscribers: gribozavr2, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D83480
2020-07-09 17:33:58 +02:00
Zixu Wang 89a0c4066b [clang][diagnostics] Add '-Wundef-prefix' warning option
Summary:
Add an `-Wundef-prefix=<arg1>,<arg2>...` option, which is similar to `-Wundef`, but only give warnings for undefined macros with the given prefixes.

Reviewers: ributzka, steven_wu, cishida, bruno, arphaman, rsmith

Reviewed By: ributzka, arphaman

Subscribers: riccibruno, dexonsmith, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D80751

This patch was authored by Zixu Wang <zixu_wang@apple.com>
2020-06-30 13:57:47 -07:00
Eric Christopher 1f593f46f3 [AST/Lex/Parse/Sema] As part of using inclusive language within
the llvm project, migrate away from the use of blacklist and whitelist.
2020-06-20 01:15:32 -07:00
Nathan James 8b0df1c1a9
[NFC] Refactor Registry loops to range for 2020-06-19 00:40:10 +01:00
Martin Boehme 8d74de9de6 [clang] Always allow including builtin headers in [no_undeclared_headers] modules.
Previously, this would fail if the builtin headers had been "claimed" by
a different module that wraps these builtin headers. libc++ does this,
for example.

This change adds a test demonstrating this situation; the test fails
without the fix.
2020-06-04 08:33:39 +02:00
Leonard Chan ef37444058 [Lexer] Fix invalid suffix diagnostic for fixed-point literals
Committing on behalf of nagart, who authored this patch.

Differential Revision: https://reviews.llvm.org/D80412
2020-05-27 16:16:56 -07:00
Alex Lorenz 11d612ac99 [clang][Preprocessor] Replace the slow translateFile call by a new, faster isMainFile check
The commit 3c28a2dc6b introduced the check that checks if we're
trying to re-enter a main file when building a preamble. Unfortunately this slowed down the preamble
compilation by 80-90% in some test cases, as translateFile is really slow. This change checks
to see if the FileEntry is the main file without calling translateFile, but by using the new
isMainFile check instead. This speeds up preamble building by 1.5-2x for certain test cases that we have.

rdar://59361291

Differential Revision: https://reviews.llvm.org/D79834
2020-05-14 14:13:34 -07:00
Sylvain Audi 7a8edcb212 [Clang] Restore replace_path_prefix instead of startswith
In D49466, sys::path::replace_path_prefix was used instead startswith for -f[macro/debug/file]-prefix-map options.
However those were reverted later (commit rG3bb24bf25767ef5bbcef958b484e7a06d8689204) due to broken Windows tests.

This patch restores those replace_path_prefix calls.
It also modifies the prefix matching to be case-insensitive under Windows.

Differential Revision : https://reviews.llvm.org/D76869
2020-05-13 13:49:14 -04:00
Nico Weber 51d938bc94 Fix bugs when an included file name is typo corrected.
D52774 fixed a bug with typo correction of includes, but didn't add
a test.

D65907 then broke recovery of typo correction of includes again,
because it extracted the code that writes to Filename to a separate
function that took the parameter not by reference.

Fix that, and also don't repeat the slash normalization computation
and fix both lookup and regular file name after recovery.

Differential Revision: https://reviews.llvm.org/D79595
2020-05-08 13:33:39 -04:00
Nico Weber d03838343f Make -Wnonportable-include-path ignore drive case on Windows.
See PR45812 for motivation.

No explicit test since I couldn't figure out how to get the
current disk drive in lower case into a form in lit where I could
mkdir it and cd to it. But the change does have test coverage in
that I can remove the case normalization in lit, and tests failed
on several bots (and for me locally if in a pwd with a lower-case
drive) without that normalization prior to this change.

Differential Revision: https://reviews.llvm.org/D79531
2020-05-07 15:54:09 -04:00
Nico Weber b9d50bdff2 Fix pr31836 on Windows too, and correctly handle repeated separators.
The approach in D30000 assumes that the '/' returned by path::begin()
is the first element for absolute paths, but that's not true on
Windows.

Also, on Windows backslashes in include lines often end up escaped
so that there are two of them. Having backslashes in include lines
is undefined behavior in most cases and implementation-defined
behavior in C++20, but since clang treats it as normal repeated
path separators, the diagnostic should too.

Unbreaks -Wnonportable-include-path for absolute paths on Windows,
and unbreaks it on non-Windows in the case of absolute paths with
repeated directory separators.

This affects e.g. the `#include __FILE__` technique if the file
passed to clang has the wrong case for the drive letter. Before:

C:\src\llvm-project>bin\clang-cl.exe c:\src\llvm-project\test.cc
c:\\src\\llvm-project\\test.cc(4,10): warning: non-portable path to file
    '"c\\srccllvm-projectctest.cc.'; specified path differs in case from
    file name on disk [-Wnonportable-include-path]
         ^

Now:

C:\src\llvm-project> out\gn\bin\clang-cl c:\src\llvm-project\test.cc
c:\\src\\llvm-project\\test.cc(4,10): warning: non-portable path to file
    '"C:\\src\\llvm-project\\test.cc"'; specified path differs in case from
    file name on disk [-Wnonportable-include-path]
         ^

Differential Revision: https://reviews.llvm.org/D79223
2020-05-01 14:17:01 -04:00
Richard Smith 20df6038ee Make -fno-char8_t disable the char8_t keyword, even in C++20.
This fixes a regression introduced in r354736, and makes our behavior
compatible with that of Clang 8 and GCC.
2020-04-28 23:49:35 -07:00
David Blaikie 4bd5fbec4b PragmaNamespace::Handlers: Use unique_ptr to simplify memory management
The API actually passes and returns ownership too, but the usage uis
complicated enough that I'm not going to unique_ptr-ify those add/remove
calls.
2020-04-28 22:31:15 -07:00
Richard Smith 0a088ead85 Improve diagnostics for missing import / #include of module.
Fix a few bugs where we would fail to properly determine header to
module correspondence when determining whether to suggest a #include or
import, and suggest a #include more often in language modes where there
is no import syntax. Generally, if the target is in a header with
include guards or #pragma once, we should suggest either #including or
importing that header, and not importing a module that happens to
textually include it.

In passing, improve the notes we attach to the corresponding
diagnostics: calling an entity that we couldn't see "previous" is
confusing.
2020-04-28 18:41:14 -07:00
Luboš Luňák 5c8c9905c2 make sure to not warn about unused macros from -D
If a PCH is used for compilation, SourceManager::isInMainFile()
returns true even for the "<built-in>" predefines area. Using -D
only for the TU compilation may trigger -Wunused-macros for it.
It is admitedly a bit fishy to set a macro only for a TU and not
for the PCH, but this works fine if the PCH does not use the macro
(I couldn't find a statement on this for Clang, but GCC explicitly
allows this in the docs).

Differential Revision: https://reviews.llvm.org/D73846
2020-04-27 21:26:13 +02:00
Kadir Cetinkaya 411a254af3
[clang] Make sure argument expansion locations are correct in presence of predefined buffer
Summary:
Macro argument expansion logic relies on skipping file IDs that created
as a result of an include. Unfortunately it fails to do that for
predefined buffer since it doesn't have a valid insertion location.

As a result of that any file ID created for an include inside the
predefined buffers breaks the traversal logic in
SourceManager::computeMacroArgsCache.

To fix this issue we first record number of created FIDs for predefined
buffer, and then skip them explicitly in source manager.

Another solution would be to just give predefined buffers a valid source
location, but it is unclear where that should be..

Reviewers: sammccall

Subscribers: cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D78649
2020-04-22 21:01:52 +02:00
Aaron Ballman 1b3f1f4436 Rename warning identifiers from cxx2a to cxx20; NFC. 2020-04-22 14:31:13 -04:00
Aaron Ballman 6a30894391 C++2a -> C++20 in some identifiers; NFC. 2020-04-21 15:37:19 -04:00
Sam McCall ee12edcb76 [Preamble] Allow recursive inclusion of header-guarded mainfile.
Summary:
This is guaranteed to be a no-op without the preamble, so should be a
no-op with it too.

Partially fixes https://github.com/clangd/clangd/issues/337
This doesn't yet work for #ifndef guards, which are not recognized in preambles.
see D78038

I can't for the life of me work out how to test this outside clangd.
The original reentrant preamble diagnostic was untested, I added a test
to clangd for that too.

Reviewers: kadircet

Subscribers: ilya-biryukov, jkorous, arphaman, usaxena95, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D78366
2020-04-20 17:28:42 +02:00
Richard Smith 6bc7502385 When making modules transitively visible, don't take into account
whether they have missing header files.

Whether a module's headers happen to be present on the local file system
should make no difference to whether we make its contents visible when
importing another module that re-exports it. If we have an up-to-date
AST file that we can load, that's all that matters.

This fixes the ability to header syntax checking for modular headers in
C++20 mode (or in prior modes where -fmodules-local-submodule-visibility
is enabled but -fmodules is not).
2020-04-17 22:49:58 -07:00