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MaggieYingYiMaggieYingYi
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[Frontend][PCH]-Add support for ignoring PCH options (-ignore-pch).
Visual Studio has an argument to ignore all PCH related switches. clang-cl has also support option /Y-. Having the same option in clang would be helpful. This commit is to add support for ignoring PCH options (-ignore-pch).
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‎clang/docs/PCHInternals.rst

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@@ -31,6 +31,16 @@ option:
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$ clang -cc1 -include-pch test.h.pch test.c -o test.s
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To ignore PCH options using ``clang -cc1``, use the option `-ignore-pch`:
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.. code-block:: bash
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$ clang -cc1 test.h -emit-pch -ignore-pch -o test.h.pch
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$ clang -cc1 -include-pch test.h.pch -ignore-pch test.c -o test.s
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This option disables precompiled headers, overrides -emit-pch and -include-pch.
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test.h.pch is not generated and not used as a prefix header.
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Design Philosophy
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-----------------
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‎clang/docs/UsersManual.rst

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@@ -1458,6 +1458,20 @@ will be processed from the PCH file. Otherwise, Clang will report an error.
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``test.h`` since ``test.h`` was included directly in the source file and not
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specified on the command line using ``-include-pch``.
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Ignoring a PCH File
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^^^^^^^^^^^^^^^^^^^
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To ignore a PCH file using Clang, the `-Xclang -ignore-pch` option is passed to
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``clang``:
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.. code-block:: console
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$ clang -x c-header test.h -Xclang -ignore-pch -o test.h.pch
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$ clang -include-pch test.h.pch -Xclang -ignore-pch test.c -o test
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This option disables precompiled headers, overrides -emit-pch and -include-pch.
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test.h.pch is not generated and not used as a prefix header.
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Relocatable PCH Files
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^^^^^^^^^^^^^^^^^^^^^
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‎clang/include/clang/Driver/Options.td

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@@ -8127,6 +8127,8 @@ def emit_header_unit : Flag<["-"], "emit-header-unit">,
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HelpText<"Generate C++20 header units from header files">;
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def emit_pch : Flag<["-"], "emit-pch">,
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HelpText<"Generate pre-compiled header file">;
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def ignore_pch : Flag<["-"], "ignore-pch">,
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HelpText<"Ignore pre-compiled header options">;
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def emit_llvm_only : Flag<["-"], "emit-llvm-only">,
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HelpText<"Build ASTs and convert to LLVM, discarding output">;
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def emit_codegen_only : Flag<["-"], "emit-codegen-only">,

‎clang/lib/Frontend/CompilerInvocation.cpp

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@@ -2982,6 +2982,15 @@ static bool ParseFrontendArgs(FrontendOptions &Opts, ArgList &Args,
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#undef FRONTEND_OPTION_WITH_MARSHALLING
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Opts.ProgramAction = frontend::ParseSyntaxOnly;
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// If -ignore-pch is used, all pch handling is disabled. clang pch-related
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// flags are removed.
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if (Args.hasArg(options::OPT_ignore_pch)) {
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Args.eraseArg(options::OPT_emit_pch);
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Args.eraseArg(options::OPT_include_pch);
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Args.eraseArg(options::OPT_ignore_pch);
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}
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if (const Arg *A = Args.getLastArg(OPT_Action_Group)) {
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OptSpecifier Opt = OptSpecifier(A->getOption().getID());
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std::optional<frontend::ActionKind> ProgramAction = getFrontendAction(Opt);

‎clang/test/PCH/Inputs/ignored-pch.h

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#ifndef IGNORED_PCH_H
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#define IGNORED_PCH_H
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inline int f() {
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return 42;
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}
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#endif // IGNORED_PCH_H

‎clang/test/PCH/ignored-pch.c

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// RUN: rm -rf %t.pch %t.ll
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// RUN: %clang_cc1 -x c-header %S/Inputs/ignored-pch.h -emit-pch -o %t.pch
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// RUN: %clang_cc1 %s -include-pch %t.pch -emit-llvm -o %t.ll
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// RUN: ls %t.pch | FileCheck --check-prefix=CHECK-PCH %s
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// RUN: ls %t.ll | FileCheck --check-prefix=CHECK-OBJ %s
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// Check that -ignore-pch causes -emit-pch and -include-pch options to be ignored.
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// RUN: rm -rf %t.pch %t.ll
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// RUN: %clang_cc1 -x c-header %S/Inputs/ignored-pch.h -ignore-pch -emit-pch -o %t.pch
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// RUN: %clang_cc1 %s -include-pch %t.pch -ignore-pch -emit-llvm -o %t.ll
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// RUN: not ls %t.pch 2>&1 | FileCheck --check-prefix=CHECK-ERROR %s
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// RUN: ls %t.ll | FileCheck --check-prefix=CHECK-OBJ %s
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// Check that -ignore-pch is passed through Driver.
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// RUN: rm -rf %t.pch %t.ll
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// RUN: %clang -x c-header %S/Inputs/ignored-pch.h -Xclang -emit-pch -o %t.pch
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// RUN: %clang -S %s -include-pch %t.pch -Xclang -emit-llvm -o %t.ll
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// RUN: ls %t.pch | FileCheck --check-prefix=CHECK-PCH %s
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// RUN: ls %t.ll | FileCheck --check-prefix=CHECK-OBJ %s
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// RUN: rm -rf %t.pch %t.ll
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// RUN: %clang -x c-header %S/Inputs/ignored-pch.h -Xclang -ignore-pch -Xclang -emit-pch -o %t.pch
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// RUN: %clang -S %s -include-pch %t.pch -Xclang -ignore-pch -Xclang -emit-llvm -o %t.ll
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// RUN: not ls %t.pch 2>&1 | FileCheck --check-prefix=CHECK-ERROR %s
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// RUN: ls %t.ll | FileCheck --check-prefix=CHECK-OBJ %s
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// Check that -ignore-pch works for multiple PCH related options.
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// Test with -building-pch-with-obj.
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// RUN: rm -rf %t.pch %t.ll
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// RUN: %clang_cc1 -x c-header %S/Inputs/ignored-pch.h -ignore-pch -emit-pch -building-pch-with-obj -o %t.pch
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// RUN: %clang_cc1 %s -include-pch %t.pch -ignore-pch -emit-llvm -building-pch-with-obj -o %t.ll
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// RUN: not ls %t.pch 2>&1 | FileCheck --check-prefix=CHECK-ERROR %s
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// RUN: ls %t.ll | FileCheck --check-prefix=CHECK-OBJ %s
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// Test with -fallow-pch-with-compiler-errors.
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// RUN: rm -rf %t.pch %t.ll
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// RUN: %clang_cc1 -x c-header %S/Inputs/ignored-pch.h -ignore-pch -emit-pch -fallow-pch-with-compiler-errors -o %t.pch
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// RUN: %clang_cc1 %s -include-pch %t.pch -ignore-pch -emit-llvm -fallow-pch-with-compiler-errors -o %t.ll
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// RUN: not ls %t.pch 2>&1 | FileCheck --check-prefix=CHECK-ERROR %s
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// RUN: ls %t.ll | FileCheck --check-prefix=CHECK-OBJ %s
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// Test with -fallow-pch-with-different-modules-cache-path.
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// RUN: rm -rf %t.pch %t.ll
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// RUN: %clang_cc1 -x c-header %S/Inputs/ignored-pch.h -emit-pch -fallow-pch-with-different-modules-cache-path -o %t.pch
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// RUN: %clang_cc1 %s -include-pch %t.pch -emit-llvm -fallow-pch-with-different-modules-cache-path -o %t.ll
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// RUN: ls %t.pch | FileCheck --check-prefix=CHECK-PCH %s
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// RUN: ls %t.ll | FileCheck --check-prefix=CHECK-OBJ %s
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// Test with -fpch-codegen.
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// RUN: rm -rf %t.pch %t.ll
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// RUN: %clang_cc1 -x c-header %S/Inputs/ignored-pch.h -emit-pch -fpch-codegen -o %t.pch
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// RUN: %clang_cc1 %s -include-pch %t.pch -emit-llvm -fpch-codegen -o %t.ll
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// RUN: ls %t.pch | FileCheck --check-prefix=CHECK-PCH %s
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// RUN: ls %t.ll | FileCheck --check-prefix=CHECK-OBJ %s
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// Test with -fpch-debuginfo.
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// RUN: rm -rf %t.pch %t.ll
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// RUN: %clang_cc1 -x c-header %S/Inputs/ignored-pch.h -emit-pch -fpch-debuginfo -o %t.pch
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// RUN: %clang_cc1 %s -include-pch %t.pch -emit-llvm -fpch-debuginfo -o %t.ll
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// RUN: ls %t.pch | FileCheck --check-prefix=CHECK-PCH %s
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// RUN: ls %t.ll | FileCheck --check-prefix=CHECK-OBJ %s
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// Test with -fpch-instantiate-templates.
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// RUN: rm -rf %t.pch %t.ll
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// RUN: %clang_cc1 -x c-header %S/Inputs/ignored-pch.h -emit-pch -fpch-instantiate-templates -o %t.pch
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// RUN: %clang_cc1 %s -include-pch %t.pch -emit-llvm -fpch-instantiate-templates -o %t.ll
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// RUN: ls %t.pch | FileCheck --check-prefix=CHECK-PCH %s
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// RUN: ls %t.ll | FileCheck --check-prefix=CHECK-OBJ %s
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// Test with -fno-pch-timestamp.
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// RUN: rm -rf %t.pch %t.ll
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// RUN: %clang_cc1 -x c-header %S/Inputs/ignored-pch.h -emit-pch -fno-pch-timestamp -o %t.pch
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// RUN: %clang_cc1 %s -include-pch %t.pch -emit-llvm -fno-pch-timestamp -o %t.ll
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// RUN: ls %t.pch | FileCheck --check-prefix=CHECK-PCH %s
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// RUN: ls %t.ll | FileCheck --check-prefix=CHECK-OBJ %s
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// Test with -fno-validate-pch.
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// RUN: rm -rf %t.pch %t.ll
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// RUN: %clang_cc1 -x c-header %S/Inputs/ignored-pch.h -emit-pch -fno-validate-pch -o %t.pch
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// RUN: %clang_cc1 %s -include-pch %t.pch -emit-llvm -fno-validate-pch -o %t.ll
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// RUN: ls %t.pch | FileCheck --check-prefix=CHECK-PCH %s
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// RUN: ls %t.ll | FileCheck --check-prefix=CHECK-OBJ %s
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// Test with -relocatable-pch.
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// RUN: rm -rf %t.pch %t.ll
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// RUN: %clang_cc1 -x c-header %S/Inputs/ignored-pch.h -emit-pch -relocatable-pch -o %t.pch
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// RUN: %clang_cc1 %s -include-pch %t.pch -emit-llvm -relocatable-pch -o %t.ll
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// RUN: ls %t.pch | FileCheck --check-prefix=CHECK-PCH %s
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// RUN: ls %t.ll | FileCheck --check-prefix=CHECK-OBJ %s
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// Test with -pch-through-hdrstop-create/-pch-through-hdrstop-use
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// RUN: rm -rf %t.pch %t.ll
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// RUN: %clang_cc1 -x c-header %S/Inputs/ignored-pch.h -emit-pch -pch-through-hdrstop-create -o %t.pch
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// RUN: %clang_cc1 %s -include-pch %t.pch -emit-llvm -pch-through-hdrstop-use -o %t.ll
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// RUN: ls %t.pch | FileCheck --check-prefix=CHECK-PCH %s
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// RUN: ls %t.ll | FileCheck --check-prefix=CHECK-OBJ %s
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// Test with AST dump output:
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// RUN: rm -rf %t.pch %t.ll
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// RUN: %clang_cc1 -x c-header %S/Inputs/ignored-pch.h -emit-pch -o %t.pch
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// RUN: %clang_cc1 %s -include-pch %t.pch -ast-dump-all | FileCheck --check-prefix=CHECK-AST-PCH %s
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// RUN: %clang_cc1 %s -include-pch %t.pch -ignore-pch -ast-dump-all | FileCheck --check-prefix=CHECK-AST %s
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// CHECK-PCH: ignored-pch.c.{{.*}}.pch
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// CHECK-OBJ: ignored-pch.c.{{.*}}.ll
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// CHECK-ERROR: ignored-pch.c.{{.*}}.pch{{'?}}: No such file or directory
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// CHECK-AST-PCH: <undeserialized declarations>
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// CHECK-AST-NOT: <undeserialized declarations>
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#include "Inputs/ignored-pch.h"
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#pragma hdrstop
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int main() {
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return f();
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}

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