From 04b419048955fc33718ba97e79f3558b6a27830e Mon Sep 17 00:00:00 2001
From: Sam McCall <sam.mccall@gmail.com>
Date: Thu, 5 May 2022 01:15:28 +0200
Subject: [Driver] Make "upgrade" of -include to include-pch optional; disable
 in clangd

If clang is passed "-include foo.h", it will rewrite to "-include-pch foo.h.pch"
before passing it to cc1, if foo.h.pch exists.

Existence is checked, but validity is not. This is probably a reasonable
assumption for the compiler itself, but not for clang-based tools where the
actual compiler may be a different version of clang, or even GCC.
In the end, we lose our -include, we gain a -include-pch that can't be used,
and the file often fails to parse.

I would like to turn this off for all non-clang invocations (i.e.
createInvocationFromCommandLine), but we have explicit tests of this behavior
for libclang and I can't work out the implications of changing it.

Instead this patch:
 - makes it optional in the driver, default on (no change)
 - makes it optional in createInvocationFromCommandLine, default on (no change)
 - changes driver to do IO through the VFS so it can be tested
 - tests the option
 - turns the option off in clangd where the problem was reported

Subsequent patches should make libclang opt in explicitly and flip the default
for all other tools. It's probably also time to extract an options struct
for createInvocationFromCommandLine.

Fixes https://github.com/clangd/clangd/issues/856
Fixes https://github.com/clangd/vscode-clangd/issues/324

Differential Revision: https://reviews.llvm.org/D124970
---
 clang/lib/Frontend/CreateInvocationFromCommandLine.cpp | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

(limited to 'clang/lib/Frontend/CreateInvocationFromCommandLine.cpp')

diff --git a/clang/lib/Frontend/CreateInvocationFromCommandLine.cpp b/clang/lib/Frontend/CreateInvocationFromCommandLine.cpp
index dee7a91..2a98aab 100644
--- a/clang/lib/Frontend/CreateInvocationFromCommandLine.cpp
+++ b/clang/lib/Frontend/CreateInvocationFromCommandLine.cpp
@@ -48,6 +48,7 @@ clang::createInvocation(ArrayRef<const char *> ArgList,
 
   // Don't check that inputs exist, they may have been remapped.
   TheDriver.setCheckInputsExist(false);
+  TheDriver.setProbePrecompiled(Opts.ProbePrecompiled);
 
   std::unique_ptr<driver::Compilation> C(TheDriver.BuildCompilation(Args));
   if (!C)
@@ -107,8 +108,8 @@ clang::createInvocation(ArrayRef<const char *> ArgList,
 std::unique_ptr<CompilerInvocation> clang::createInvocationFromCommandLine(
     ArrayRef<const char *> Args, IntrusiveRefCntPtr<DiagnosticsEngine> Diags,
     IntrusiveRefCntPtr<llvm::vfs::FileSystem> VFS, bool ShouldRecoverOnErrors,
-    std::vector<std::string> *CC1Args) {
+    std::vector<std::string> *CC1Args, bool ProbePrecompiled) {
   return createInvocation(
-      Args,
-      CreateInvocationOptions{Diags, VFS, ShouldRecoverOnErrors, CC1Args});
+      Args, CreateInvocationOptions{Diags, VFS, ShouldRecoverOnErrors,
+                                    ProbePrecompiled, CC1Args});
 }
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