subject:"\[PATCH\] D31343\: Add an attribute plugin example"

[PATCH] D31343: Add an attribute plugin example

2020-03-26 Thread John Brawn via Phabricator via cfe-commits

john.brawn added a comment.

Release note added: https://reviews.llvm.org/rG0cff81cff05d


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  rG LLVM Github Monorepo

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[PATCH] D31343: Add an attribute plugin example

2020-03-25 Thread John Brawn via Phabricator via cfe-commits

This revision was automatically updated to reflect the committed changes.
Closed by commit rG3f03c12a51be: Add an attribute plugin example (authored by 
john.brawn).

Repository:
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Files:
  clang/docs/ClangPlugins.rst
  clang/examples/Attribute/Attribute.cpp
  clang/examples/Attribute/CMakeLists.txt
  clang/examples/CMakeLists.txt
  clang/test/CMakeLists.txt
  clang/test/Frontend/plugin-attribute.cpp

Index: clang/test/Frontend/plugin-attribute.cpp
===
--- /dev/null
+++ clang/test/Frontend/plugin-attribute.cpp
@@ -0,0 +1,25 @@
+// RUN: %clang -fplugin=%llvmshlibdir/Attribute%pluginext -emit-llvm -S %s -o - 2>&1 | FileCheck %s --check-prefix=ATTRIBUTE
+// RUN: not %clang -fplugin=%llvmshlibdir/Attribute%pluginext -emit-llvm -DBAD_ATTRIBUTE -S %s -o - 2>&1 | FileCheck %s --check-prefix=BADATTRIBUTE
+// REQUIRES: plugins, examples
+
+void fn1a() __attribute__((example)) { }
+[[example]] void fn1b() { }
+[[plugin::example]] void fn1c() { }
+void fn2() __attribute__((example("somestring"))) { }
+// ATTRIBUTE: warning: 'example' attribute only applies to functions
+int var1 __attribute__((example("otherstring"))) = 1;
+
+// ATTRIBUTE: [[STR1_VAR:@.+]] = private unnamed_addr constant [10 x i8] c"example()\00"
+// ATTRIBUTE: [[STR2_VAR:@.+]] = private unnamed_addr constant [20 x i8] c"example(somestring)\00"
+// ATTRIBUTE: @llvm.global.annotations = {{.*}}@{{.*}}fn1a{{.*}}[[STR1_VAR]]{{.*}}@{{.*}}fn1b{{.*}}[[STR1_VAR]]{{.*}}@{{.*}}fn1c{{.*}}[[STR1_VAR]]{{.*}}@{{.*}}fn2{{.*}}[[STR2_VAR]]
+
+#ifdef BAD_ATTRIBUTE
+class Example {
+  // BADATTRIBUTE: error: 'example' attribute only allowed at file scope
+  void __attribute__((example)) fn3();
+};
+// BADATTRIBUTE: error: 'example' attribute requires a string
+void fn4() __attribute__((example(123))) { }
+// BADATTRIBUTE: error: 'example' attribute takes no more than 1 argument
+void fn5() __attribute__((example("a","b"))) { }
+#endif
Index: clang/test/CMakeLists.txt
===
--- clang/test/CMakeLists.txt
+++ clang/test/CMakeLists.txt
@@ -81,6 +81,7 @@
 
 if (CLANG_BUILD_EXAMPLES)
   list(APPEND CLANG_TEST_DEPS
+Attribute
 AnnotateFunctions
 clang-interpreter
 PrintFunctionNames
Index: clang/examples/CMakeLists.txt
===
--- clang/examples/CMakeLists.txt
+++ clang/examples/CMakeLists.txt
@@ -6,3 +6,4 @@
 add_subdirectory(clang-interpreter)
 add_subdirectory(PrintFunctionNames)
 add_subdirectory(AnnotateFunctions)
+add_subdirectory(Attribute)
Index: clang/examples/Attribute/CMakeLists.txt
===
--- /dev/null
+++ clang/examples/Attribute/CMakeLists.txt
@@ -0,0 +1,11 @@
+add_llvm_library(Attribute MODULE Attribute.cpp PLUGIN_TOOL clang)
+
+if(LLVM_ENABLE_PLUGINS AND (WIN32 OR CYGWIN))
+  target_link_libraries(AnnotateFunctions ${cmake_2_8_12_PRIVATE}
+clangAST
+clangBasic
+clangFrontend
+clangLex
+LLVMSupport
+)
+endif()
Index: clang/examples/Attribute/Attribute.cpp
===
--- /dev/null
+++ clang/examples/Attribute/Attribute.cpp
@@ -0,0 +1,80 @@
+//===- Attribute.cpp --===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===--===//
+//
+// Example clang plugin which adds an an annotation to file-scope declarations
+// with the 'example' attribute.
+//
+//===--===//
+
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/Attr.h"
+#include "clang/Sema/ParsedAttr.h"
+#include "clang/Sema/Sema.h"
+#include "clang/Sema/SemaDiagnostic.h"
+#include "llvm/IR/Attributes.h"
+using namespace clang;
+
+namespace {
+
+struct ExampleAttrInfo : public ParsedAttrInfo {
+  ExampleAttrInfo() {
+// Can take an optional string argument (the check that the argument
+// actually is a string happens in handleDeclAttribute).
+OptArgs = 1;
+// GNU-style __attribute__(("example")) and C++-style [[example]] and
+// [[plugin::example]] supported.
+Spellings.push_back({ParsedAttr::AS_GNU, "example"});
+Spellings.push_back({ParsedAttr::AS_CXX11, "example"});
+Spellings.push_back({ParsedAttr::AS_CXX11, "plugin::example"});
+  }
+
+  bool diagAppertainsToDecl(Sema &S, const ParsedAttr &Attr,
+const Decl *D) const override {
+// This attribute appertains to functions only.
+if (!isa(D)) {
+  S.Diag(Attr.getLoc(), diag::

[PATCH] D31343: Add an attribute plugin example

2020-03-25 Thread Aaron Ballman via Phabricator via cfe-commits

aaron.ballman added a comment.

I think this was the last remaining review for the feature to support 
attributes as plugins, yes? If so, can you please add a release note about the 
feature to the release notes?


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[PATCH] D31343: Add an attribute plugin example

2020-03-24 Thread Aaron Ballman via Phabricator via cfe-commits

aaron.ballman accepted this revision.
aaron.ballman added a comment.
This revision is now accepted and ready to land.

LGTM, thank you!


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[PATCH] D31343: Add an attribute plugin example

2020-03-24 Thread John Brawn via Phabricator via cfe-commits

john.brawn updated this revision to Diff 252309.
john.brawn added a comment.

A few small changes:

- Don't start C++11 spelling with :: (changes to name normalisation to allow 
this are in D76704 )
- Don't check that the Decl is null in diagAppertainsToDecl
- Return AttributeNotApplied on errors in handleDeclAttribute


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Files:
  clang/docs/ClangPlugins.rst
  clang/examples/Attribute/Attribute.cpp
  clang/examples/Attribute/CMakeLists.txt
  clang/examples/CMakeLists.txt
  clang/test/CMakeLists.txt
  clang/test/Frontend/plugin-attribute.cpp

Index: clang/test/Frontend/plugin-attribute.cpp
===
--- /dev/null
+++ clang/test/Frontend/plugin-attribute.cpp
@@ -0,0 +1,25 @@
+// RUN: %clang -fplugin=%llvmshlibdir/Attribute%pluginext -emit-llvm -S %s -o - 2>&1 | FileCheck %s --check-prefix=ATTRIBUTE
+// RUN: not %clang -fplugin=%llvmshlibdir/Attribute%pluginext -emit-llvm -DBAD_ATTRIBUTE -S %s -o - 2>&1 | FileCheck %s --check-prefix=BADATTRIBUTE
+// REQUIRES: plugins, examples
+
+void fn1a() __attribute__((example)) { }
+[[example]] void fn1b() { }
+[[plugin::example]] void fn1c() { }
+void fn2() __attribute__((example("somestring"))) { }
+// ATTRIBUTE: warning: 'example' attribute only applies to functions
+int var1 __attribute__((example("otherstring"))) = 1;
+
+// ATTRIBUTE: [[STR1_VAR:@.+]] = private unnamed_addr constant [10 x i8] c"example()\00"
+// ATTRIBUTE: [[STR2_VAR:@.+]] = private unnamed_addr constant [20 x i8] c"example(somestring)\00"
+// ATTRIBUTE: @llvm.global.annotations = {{.*}}@{{.*}}fn1a{{.*}}[[STR1_VAR]]{{.*}}@{{.*}}fn1b{{.*}}[[STR1_VAR]]{{.*}}@{{.*}}fn1c{{.*}}[[STR1_VAR]]{{.*}}@{{.*}}fn2{{.*}}[[STR2_VAR]]
+
+#ifdef BAD_ATTRIBUTE
+class Example {
+  // BADATTRIBUTE: error: 'example' attribute only allowed at file scope
+  void __attribute__((example)) fn3();
+};
+// BADATTRIBUTE: error: 'example' attribute requires a string
+void fn4() __attribute__((example(123))) { }
+// BADATTRIBUTE: error: 'example' attribute takes no more than 1 argument
+void fn5() __attribute__((example("a","b"))) { }
+#endif
Index: clang/test/CMakeLists.txt
===
--- clang/test/CMakeLists.txt
+++ clang/test/CMakeLists.txt
@@ -81,6 +81,7 @@
 
 if (CLANG_BUILD_EXAMPLES)
   list(APPEND CLANG_TEST_DEPS
+Attribute
 AnnotateFunctions
 clang-interpreter
 PrintFunctionNames
Index: clang/examples/CMakeLists.txt
===
--- clang/examples/CMakeLists.txt
+++ clang/examples/CMakeLists.txt
@@ -6,3 +6,4 @@
 add_subdirectory(clang-interpreter)
 add_subdirectory(PrintFunctionNames)
 add_subdirectory(AnnotateFunctions)
+add_subdirectory(Attribute)
Index: clang/examples/Attribute/CMakeLists.txt
===
--- /dev/null
+++ clang/examples/Attribute/CMakeLists.txt
@@ -0,0 +1,11 @@
+add_llvm_library(Attribute MODULE Attribute.cpp PLUGIN_TOOL clang)
+
+if(LLVM_ENABLE_PLUGINS AND (WIN32 OR CYGWIN))
+  target_link_libraries(AnnotateFunctions ${cmake_2_8_12_PRIVATE}
+clangAST
+clangBasic
+clangFrontend
+clangLex
+LLVMSupport
+)
+endif()
Index: clang/examples/Attribute/Attribute.cpp
===
--- /dev/null
+++ clang/examples/Attribute/Attribute.cpp
@@ -0,0 +1,80 @@
+//===- Attribute.cpp --===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===--===//
+//
+// Example clang plugin which adds an an annotation to file-scope declarations
+// with the 'example' attribute.
+//
+//===--===//
+
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/Attr.h"
+#include "clang/Sema/ParsedAttr.h"
+#include "clang/Sema/Sema.h"
+#include "clang/Sema/SemaDiagnostic.h"
+#include "llvm/IR/Attributes.h"
+using namespace clang;
+
+namespace {
+
+struct ExampleAttrInfo : public ParsedAttrInfo {
+  ExampleAttrInfo() {
+// Can take an optional string argument (the check that the argument
+// actually is a string happens in handleDeclAttribute).
+OptArgs = 1;
+// GNU-style __attribute__(("example")) and C++-style [[example]] and
+// [[plugin::example]] supported.
+Spellings.push_back({ParsedAttr::AS_GNU, "example"});
+Spellings.push_back({ParsedAttr::AS_CXX11, "example"});
+Spellings.push_back({ParsedAttr::AS_CXX11, "plugin::example"});
+  }
+
+  bool diagAppertainsToDecl(Sema &S, const ParsedAttr &Attr,
+

[PATCH] D31343: Add an attribute plugin example

2020-03-23 Thread Erich Keane via Phabricator via cfe-commits

erichkeane added a comment.

In D31343#1937588 , @aaron.ballman 
wrote:

> In D31343#1936810 , @Jasmin wrote:
>
> > Hello John!
> >
> > I was encouraged by Erich after a talk I had with him and Aaron on IRC to 
> > contact you about an use case for this plugin.
> >
> > I wanted to use user-specified/unknown attributes to annotate code and was 
> > told that they are not propagated through
> >  the AST and therefore it is not possible at the moment to use them for 
> > that purpose. Aaron's and Erich's idea was to
> >  allow kind of no-op attributes in the plugin so that the compiler would 
> > not issue a warning about the unknown attribute.
> >  This would be helpful for the user being able to define a list of 
> > attributes the user knows and expects, so that a compilation
> >  would not be spammed unnecessarily and misspelled attributes would still 
> > stand out.
> >
> > Being able to get the cursor or displayName of the attribute would 
> > essentially be enough to use it in tooling.
> >
> > We can use __attribute__((annotate(smth))) at the time being to achieve the 
> > same goal, but it is much more writing to do
> >  and also vendor specific. Being able to do the same with attributes would 
> > give them a real purpose, other than having
> >  to be accepted and not causing an error. Also they have to be supported by 
> > the language and we don't have to use
> >  macros to annotate the code.
> >
> > To summarize it would be nice to have:
> >
> > - user supplied unknown attributes to suppress a warning
> > - unknown attributes propagated in the AST
> >
> >   I hope I summarized this correctly and could get through the gist of this 
> > idea.
> >
> >   Looking forward to hearing from you.
>
>
> For reference: the current set of patches John has been working on allow you 
> to load a plugin to let the frontend parse an attribute with an arbitrary 
> spelling, but it does not have a way for you to register a new attribute AST 
> node that gets attached to anything in the AST. Instead, you create an 
> existing semantic attribute (such as an `AnnotateAttr`) and add that to the 
> AST.
>
> I think this is a great request to keep in mind for John or anyone else who 
> wants to extend this plugin functionality to allow for generating custom 
> attribute AST nodes (which is of interest for tools like clang static 
> analyzer or clang tidy plugins that may consume the clang AST). This 
> functionality would also have to keep the libclang C indexing interface in 
> mind, as that's another area of the compiler where this functionality would 
> be useful.


Hmm... I wonder if there is value to having these plugin-attributes auto-create 
a PluginAnnotateAttr or something (some otherwise bikeshedded attribute) for 
exactly Jasmin's use case.  That way the plugin author simply needs to list the 
possible spellings.


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[PATCH] D31343: Add an attribute plugin example

2020-03-23 Thread Aaron Ballman via Phabricator via cfe-commits

aaron.ballman added a comment.

In D31343#1936810 , @Jasmin wrote:

> Hello John!
>
> I was encouraged by Erich after a talk I had with him and Aaron on IRC to 
> contact you about an use case for this plugin.
>
> I wanted to use user-specified/unknown attributes to annotate code and was 
> told that they are not propagated through
>  the AST and therefore it is not possible at the moment to use them for that 
> purpose. Aaron's and Erich's idea was to
>  allow kind of no-op attributes in the plugin so that the compiler would not 
> issue a warning about the unknown attribute.
>  This would be helpful for the user being able to define a list of attributes 
> the user knows and expects, so that a compilation
>  would not be spammed unnecessarily and misspelled attributes would still 
> stand out.
>
> Being able to get the cursor or displayName of the attribute would 
> essentially be enough to use it in tooling.
>
> We can use __attribute__((annotate(smth))) at the time being to achieve the 
> same goal, but it is much more writing to do
>  and also vendor specific. Being able to do the same with attributes would 
> give them a real purpose, other than having
>  to be accepted and not causing an error. Also they have to be supported by 
> the language and we don't have to use
>  macros to annotate the code.
>
> To summarize it would be nice to have:
>
> - user supplied unknown attributes to suppress a warning
> - unknown attributes propagated in the AST
>
>   I hope I summarized this correctly and could get through the gist of this 
> idea.
>
>   Looking forward to hearing from you.

For reference: the current set of patches John has been working on allow you to 
load a plugin to let the frontend parse an attribute with an arbitrary 
spelling, but it does not have a way for you to register a new attribute AST 
node that gets attached to anything in the AST. Instead, you create an existing 
semantic attribute (such as an `AnnotateAttr`) and add that to the AST.

I think this is a great request to keep in mind for John or anyone else who 
wants to extend this plugin functionality to allow for generating custom 
attribute AST nodes (which is of interest for tools like clang static analyzer 
or clang tidy plugins that may consume the clang AST). This functionality would 
also have to keep the libclang C indexing interface in mind, as that's another 
area of the compiler where this functionality would be useful.

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[PATCH] D31343: Add an attribute plugin example

2020-03-23 Thread Jasmin Fazlic via Phabricator via cfe-commits

Jasmin added a comment.

Hello John!

I was encouraged by Erich after a talk I had with him and Aaron on IRC to 
contact you about an use case for this plugin.

I wanted to use user-specified/unknown attributes to annotate code and was told 
that they are not propagated through
the AST and therefore it is not possible at the moment to use them for that 
purpose. Aaron's and Erich's idea was to
allow kind of no-op attributes in the plugin so that the compiler would not 
issue a warning about the unknown attribute.
This would be helpful for the user being able to define a list of attributes 
the user knows and expects, so that a compilation
would not be spammed unnecessarily and misspelled attributes would still stand 
out.

Being able to get the cursor or displayName of the attribute would essentially 
be enough to use it in tooling.

We can use __attribute__((annotate(smth))) at the time being to achieve the 
same goal, but it is much more writing to do
and also vendor specific. Being able to do the same with attributes would give 
them a real purpose, other than having
to be accepted and not causing an error. Also they have to be supported by the 
language and we don't have to use
macros to annotate the code.

To summarize it would be nice to have:

- user supplied unknown attributes to suppress a warning
- unknown attributes propagated in the AST

I hope I summarized this correctly and could get through the gist of this idea.

Looking forward to hearing from you.

Best regards, Jasmin


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[PATCH] D31343: Add an attribute plugin example

2020-03-20 Thread Aaron Ballman via Phabricator via cfe-commits

aaron.ballman added inline comments.



Comment at: clang/examples/Attribute/Attribute.cpp:35
+Spellings.push_back({ParsedAttr::AS_GNU, "example"});
+Spellings.push_back({ParsedAttr::AS_CXX11, "::example"});
+Spellings.push_back({ParsedAttr::AS_CXX11, "plugin::example"});

john.brawn wrote:
> aaron.ballman wrote:
> > This is not a valid spelling for an attribute (we should probably assert 
> > that an attribute-scoped-token does not have an empty scope).
> "::example" is actually how an unscoped spelling is specified - normalizeName 
> in Basic/Attributes.cpp adds a "::" to the start if there's no scope, and the 
> tablegen-generated getAttrKind expects it as well.
It's not how an unscoped spelling is specified by either C or C++ -- in both 
languages, that would be an error. I don't think we want to leak this 
implementation detail out to the user as it will be confusing to them.



Comment at: clang/examples/Attribute/Attribute.cpp:42
+// This attribute appertains to functions only.
+if (!D || !isa(D)) {
+  S.Diag(Attr.getLoc(), diag::warn_attribute_wrong_decl_type_str)

john.brawn wrote:
> aaron.ballman wrote:
> > I don't think `D` can ever be null, can it?
> I don't know, but this is how the auto-generated diagAppertainsToDecl 
> functions do it.
I'll fix that up -- I just verified that `D` can never be null. 
`Sema::ProcessDeclAttributeList` dereferences `D` unconditionally and has for a 
long time.


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[PATCH] D31343: Add an attribute plugin example

2020-03-18 Thread John Brawn via Phabricator via cfe-commits

john.brawn updated this revision to Diff 251114.
john.brawn added a comment.

Updated to match the changes to D31342 


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Files:
  clang/docs/ClangPlugins.rst
  clang/examples/Attribute/Attribute.cpp
  clang/examples/Attribute/CMakeLists.txt
  clang/examples/CMakeLists.txt
  clang/test/CMakeLists.txt
  clang/test/Frontend/plugin-attribute.cpp

Index: clang/test/Frontend/plugin-attribute.cpp
===
--- /dev/null
+++ clang/test/Frontend/plugin-attribute.cpp
@@ -0,0 +1,25 @@
+// RUN: %clang -fplugin=%llvmshlibdir/Attribute%pluginext -emit-llvm -S %s -o - 2>&1 | FileCheck %s --check-prefix=ATTRIBUTE
+// RUN: not %clang -fplugin=%llvmshlibdir/Attribute%pluginext -emit-llvm -DBAD_ATTRIBUTE -S %s -o - 2>&1 | FileCheck %s --check-prefix=BADATTRIBUTE
+// REQUIRES: plugins, examples
+
+void fn1a() __attribute__((example)) { }
+[[example]] void fn1b() { }
+[[plugin::example]] void fn1c() { }
+void fn2() __attribute__((example("somestring"))) { }
+// ATTRIBUTE: warning: 'example' attribute only applies to functions
+int var1 __attribute__((example("otherstring"))) = 1;
+
+// ATTRIBUTE: [[STR1_VAR:@.+]] = private unnamed_addr constant [10 x i8] c"example()\00"
+// ATTRIBUTE: [[STR2_VAR:@.+]] = private unnamed_addr constant [20 x i8] c"example(somestring)\00"
+// ATTRIBUTE: @llvm.global.annotations = {{.*}}@{{.*}}fn1a{{.*}}[[STR1_VAR]]{{.*}}@{{.*}}fn1b{{.*}}[[STR1_VAR]]{{.*}}@{{.*}}fn1c{{.*}}[[STR1_VAR]]{{.*}}@{{.*}}fn2{{.*}}[[STR2_VAR]]
+
+#ifdef BAD_ATTRIBUTE
+class Example {
+  // BADATTRIBUTE: error: 'example' attribute only allowed at file scope
+  void __attribute__((example)) fn3();
+};
+// BADATTRIBUTE: error: 'example' attribute requires a string
+void fn4() __attribute__((example(123))) { }
+// BADATTRIBUTE: error: 'example' attribute takes no more than 1 argument
+void fn5() __attribute__((example("a","b"))) { }
+#endif
Index: clang/test/CMakeLists.txt
===
--- clang/test/CMakeLists.txt
+++ clang/test/CMakeLists.txt
@@ -81,6 +81,7 @@
 
 if (CLANG_BUILD_EXAMPLES)
   list(APPEND CLANG_TEST_DEPS
+Attribute
 AnnotateFunctions
 clang-interpreter
 PrintFunctionNames
Index: clang/examples/CMakeLists.txt
===
--- clang/examples/CMakeLists.txt
+++ clang/examples/CMakeLists.txt
@@ -6,3 +6,4 @@
 add_subdirectory(clang-interpreter)
 add_subdirectory(PrintFunctionNames)
 add_subdirectory(AnnotateFunctions)
+add_subdirectory(Attribute)
Index: clang/examples/Attribute/CMakeLists.txt
===
--- /dev/null
+++ clang/examples/Attribute/CMakeLists.txt
@@ -0,0 +1,11 @@
+add_llvm_library(Attribute MODULE Attribute.cpp PLUGIN_TOOL clang)
+
+if(LLVM_ENABLE_PLUGINS AND (WIN32 OR CYGWIN))
+  target_link_libraries(AnnotateFunctions ${cmake_2_8_12_PRIVATE}
+clangAST
+clangBasic
+clangFrontend
+clangLex
+LLVMSupport
+)
+endif()
Index: clang/examples/Attribute/Attribute.cpp
===
--- /dev/null
+++ clang/examples/Attribute/Attribute.cpp
@@ -0,0 +1,78 @@
+//===- Attribute.cpp --===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===--===//
+//
+// Example clang plugin which adds an an annotation to file-scope declarations
+// with the 'example' attribute.
+//
+//===--===//
+
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/Attr.h"
+#include "clang/Sema/ParsedAttr.h"
+#include "clang/Sema/Sema.h"
+#include "clang/Sema/SemaDiagnostic.h"
+#include "llvm/IR/Attributes.h"
+using namespace clang;
+
+namespace {
+
+struct ExampleAttrInfo : public ParsedAttrInfo {
+  ExampleAttrInfo() {
+// Can take an optional string argument (the check that the argument
+// actually is a string happens in handleDeclAttribute).
+OptArgs = 1;
+// GNU-style __attribute__(("example")) and C++-style [[example]] and
+// [[plugin::example]] supported.
+Spellings.push_back({ParsedAttr::AS_GNU, "example"});
+Spellings.push_back({ParsedAttr::AS_CXX11, "::example"});
+Spellings.push_back({ParsedAttr::AS_CXX11, "plugin::example"});
+  }
+
+  bool diagAppertainsToDecl(Sema &S, const ParsedAttr &Attr,
+const Decl *D) const override {
+// This attribute appertains to functions only.
+if (!D || !isa(D)) {
+  S.Diag(Attr.getLoc(), diag::warn_attribute_wrong_decl_type_str)
+

[PATCH] D31343: Add an attribute plugin example

2020-03-05 Thread Aaron Ballman via Phabricator via cfe-commits

aaron.ballman added a comment.

In D31343#1902903 , @john.brawn wrote:

> I've been looking into attribute merging, and as far as I can tell there's 
> two things going on:
>
> - In SemaDeclAttr.cpp, the various handleXyzAttr functions may call 
> mergeXyzAttr to handle clashes with other attributes within the same 
> declaration.
> - In SemaDecl.cpp, several functions call mergeDeclAttributes, which calls 
> mergeXyzAttr, to handle clashes with attributes in a previous declaration of 
> the same thing.


Agreed.

> For the first kind, the handleDeclAttribute function defined for a plugin 
> attribute can check for and handle clashes with other attributes.

Agreed.

> For the second kind, at that point we're using subclasses of Attr which means 
> we're beyond the scope of plugin attributes which just work in the realm of 
> ParsedAttrs.

Yeah, we are using semantic attributes at that point rather than parsed 
attributes.

> So I think things are OK, though I guess it depends on what exactly your 
> plugin is doing - our use-case is that the plugin-defined attribute is just 
> used to set an AnnotateAttr, which is used to tell a plugin-defined LLVM pass 
> that it needs to do something in that function, so we don't need anything 
> special to happen with regards to attribute merging.

I think things are fine for your example plugin. The scenario I'm worried about 
is when users want to add their own semantic attributes that need to be merged, 
or if they're using an existing semantic attribute but need to add custom 
merging logic to it for their own needs.


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[PATCH] D31343: Add an attribute plugin example

2020-03-03 Thread John Brawn via Phabricator via cfe-commits

john.brawn added a comment.

I've been looking into attribute merging, and as far as I can tell there's two 
things going on:

- In SemaDeclAttr.cpp, the various handleXyzAttr functions may call 
mergeXyzAttr to handle clashes with other attributes within the same 
declaration.
- In SemaDecl.cpp, several functions call mergeDeclAttributes, which calls 
mergeXyzAttr, to handle clashes with attributes in a previous declaration of 
the same thing.

For the first kind, the handleDeclAttribute function defined for a plugin 
attribute can check for and handle clashes with other attributes. For the 
second kind, at that point we're using subclasses of Attr which means we're 
beyond the scope of plugin attributes which just work in the realm of 
ParsedAttrs.

So I think things are OK, though I guess it depends on what exactly your plugin 
is doing - our use-case is that the plugin-defined attribute is just used to 
set an AnnotateAttr, which is used to tell a plugin-defined LLVM pass that it 
needs to do something in that function, so we don't need anything special to 
happen with regards to attribute merging.


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[PATCH] D31343: Add an attribute plugin example

2020-03-02 Thread John Brawn via Phabricator via cfe-commits

john.brawn marked 2 inline comments as done.
john.brawn added inline comments.



Comment at: clang/examples/Attribute/Attribute.cpp:35
+Spellings.push_back({ParsedAttr::AS_GNU, "example"});
+Spellings.push_back({ParsedAttr::AS_CXX11, "::example"});
+Spellings.push_back({ParsedAttr::AS_CXX11, "plugin::example"});

aaron.ballman wrote:
> This is not a valid spelling for an attribute (we should probably assert that 
> an attribute-scoped-token does not have an empty scope).
"::example" is actually how an unscoped spelling is specified - normalizeName 
in Basic/Attributes.cpp adds a "::" to the start if there's no scope, and the 
tablegen-generated getAttrKind expects it as well.



Comment at: clang/examples/Attribute/Attribute.cpp:42
+// This attribute appertains to functions only.
+if (!D || !isa(D)) {
+  S.Diag(Attr.getLoc(), diag::warn_attribute_wrong_decl_type_str)

aaron.ballman wrote:
> I don't think `D` can ever be null, can it?
I don't know, but this is how the auto-generated diagAppertainsToDecl functions 
do it.


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[PATCH] D31343: Add an attribute plugin example

2020-03-02 Thread John Brawn via Phabricator via cfe-commits

john.brawn updated this revision to Diff 247683.
john.brawn added a comment.

Rebased and added link in documentation.


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Files:
  clang/docs/ClangPlugins.rst
  clang/examples/Attribute/Attribute.cpp
  clang/examples/Attribute/CMakeLists.txt
  clang/examples/CMakeLists.txt
  clang/test/CMakeLists.txt
  clang/test/Frontend/plugin-attribute.cpp

Index: clang/test/Frontend/plugin-attribute.cpp
===
--- /dev/null
+++ clang/test/Frontend/plugin-attribute.cpp
@@ -0,0 +1,25 @@
+// RUN: %clang -fplugin=%llvmshlibdir/Attribute%pluginext -emit-llvm -S %s -o - 2>&1 | FileCheck %s --check-prefix=ATTRIBUTE
+// RUN: not %clang -fplugin=%llvmshlibdir/Attribute%pluginext -emit-llvm -DBAD_ATTRIBUTE -S %s -o - 2>&1 | FileCheck %s --check-prefix=BADATTRIBUTE
+// REQUIRES: plugins, examples
+
+void fn1a() __attribute__((example)) { }
+[[example]] void fn1b() { }
+[[plugin::example]] void fn1c() { }
+void fn2() __attribute__((example("somestring"))) { }
+// ATTRIBUTE: warning: 'example' attribute only applies to functions
+int var1 __attribute__((example("otherstring"))) = 1;
+
+// ATTRIBUTE: [[STR1_VAR:@.+]] = private unnamed_addr constant [10 x i8] c"example()\00"
+// ATTRIBUTE: [[STR2_VAR:@.+]] = private unnamed_addr constant [20 x i8] c"example(somestring)\00"
+// ATTRIBUTE: @llvm.global.annotations = {{.*}}@{{.*}}fn1a{{.*}}[[STR1_VAR]]{{.*}}@{{.*}}fn1b{{.*}}[[STR1_VAR]]{{.*}}@{{.*}}fn1c{{.*}}[[STR1_VAR]]{{.*}}@{{.*}}fn2{{.*}}[[STR2_VAR]]
+
+#ifdef BAD_ATTRIBUTE
+class Example {
+  // BADATTRIBUTE: error: 'example' attribute only allowed at file scope
+  void __attribute__((example)) fn3();
+};
+// BADATTRIBUTE: error: 'example' attribute requires a string
+void fn4() __attribute__((example(123))) { }
+// BADATTRIBUTE: error: 'example' attribute takes no more than 1 argument
+void fn5() __attribute__((example("a","b"))) { }
+#endif
Index: clang/test/CMakeLists.txt
===
--- clang/test/CMakeLists.txt
+++ clang/test/CMakeLists.txt
@@ -72,6 +72,7 @@
 
 if (CLANG_BUILD_EXAMPLES)
   list(APPEND CLANG_TEST_DEPS
+Attribute
 AnnotateFunctions
 clang-interpreter
 PrintFunctionNames
Index: clang/examples/CMakeLists.txt
===
--- clang/examples/CMakeLists.txt
+++ clang/examples/CMakeLists.txt
@@ -6,3 +6,4 @@
 add_subdirectory(clang-interpreter)
 add_subdirectory(PrintFunctionNames)
 add_subdirectory(AnnotateFunctions)
+add_subdirectory(Attribute)
Index: clang/examples/Attribute/CMakeLists.txt
===
--- /dev/null
+++ clang/examples/Attribute/CMakeLists.txt
@@ -0,0 +1,11 @@
+add_llvm_library(Attribute MODULE Attribute.cpp PLUGIN_TOOL clang)
+
+if(LLVM_ENABLE_PLUGINS AND (WIN32 OR CYGWIN))
+  target_link_libraries(AnnotateFunctions ${cmake_2_8_12_PRIVATE}
+clangAST
+clangBasic
+clangFrontend
+clangLex
+LLVMSupport
+)
+endif()
Index: clang/examples/Attribute/Attribute.cpp
===
--- /dev/null
+++ clang/examples/Attribute/Attribute.cpp
@@ -0,0 +1,78 @@
+//===- Attribute.cpp --===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===--===//
+//
+// Example clang plugin which adds an an annotation to file-scope declarations
+// with the 'example' attribute.
+//
+//===--===//
+
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/Attr.h"
+#include "clang/Sema/ParsedAttr.h"
+#include "clang/Sema/Sema.h"
+#include "clang/Sema/SemaDiagnostic.h"
+#include "llvm/IR/Attributes.h"
+using namespace clang;
+
+namespace {
+
+struct ExampleAttrInfo : public ParsedAttrInfo {
+  ExampleAttrInfo() {
+// Can take an optional string argument (the check that the argument
+// actually is a string happens in handleDeclAttribute).
+OptArgs = 1;
+// GNU-style __attribute__(("example")) and C++-style [[example]] and
+// [[plugin::example]] supported.
+Spellings.push_back({ParsedAttr::AS_GNU, "example"});
+Spellings.push_back({ParsedAttr::AS_CXX11, "::example"});
+Spellings.push_back({ParsedAttr::AS_CXX11, "plugin::example"});
+  }
+
+  virtual bool diagAppertainsToDecl(Sema &S, const ParsedAttr &Attr,
+const Decl *D) const {
+// This attribute appertains to functions only.
+if (!D || !isa(D)) {
+  S.Diag(Attr.getLoc(), diag::warn_attribute_wrong_decl_type_str)
+<< Attr << "functions";
+

[PATCH] D31343: Add an attribute plugin example

2020-02-27 Thread Aaron Ballman via Phabricator via cfe-commits

aaron.ballman added inline comments.



Comment at: clang/examples/Attribute/Attribute.cpp:35
+  }
+  virtual bool handleDeclAttribute(Sema &S, Decl *D,
+   const ParsedAttr &Attr) const {

john.brawn wrote:
> aaron.ballman wrote:
> > It is unclear to me how a user would add an attribute that needs to follow 
> > the merge pattern we use in `mergeDeclAttribute()`.
> I'm guessing it's probably not possible, from a quick look at 
> mergeDeclAttribute.
That... seems like a problem that we should fix (or at least have a plan for 
fixing). Merging attributes is important so that we can have attributes with 
consistency checks between declarations for anything other than basic attribute 
inheritance. FWIW, there are 20+ attributes that already need this 
functionality, so it does get used relatively often.



Comment at: clang/examples/Attribute/Attribute.cpp:35
+Spellings.push_back({ParsedAttr::AS_GNU, "example"});
+Spellings.push_back({ParsedAttr::AS_CXX11, "::example"});
+Spellings.push_back({ParsedAttr::AS_CXX11, "plugin::example"});

This is not a valid spelling for an attribute (we should probably assert that 
an attribute-scoped-token does not have an empty scope).



Comment at: clang/examples/Attribute/Attribute.cpp:42
+// This attribute appertains to functions only.
+if (!D || !isa(D)) {
+  S.Diag(Attr.getLoc(), diag::warn_attribute_wrong_decl_type_str)

I don't think `D` can ever be null, can it?


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[PATCH] D31343: Add an attribute plugin example

2020-02-27 Thread John Brawn via Phabricator via cfe-commits

john.brawn marked 5 inline comments as done.
john.brawn added inline comments.



Comment at: clang/examples/Attribute/Attribute.cpp:25
+struct ExampleAttrInfo : public ParsedAttrInfo {
+  ExampleAttrInfo() {
+// Set the kind to NoSemaHandlerAttribute to make sure clang doesn't assume

aaron.ballman wrote:
> It would be really handy for the example to show how to list subjects for the 
> declaration attribute, as that's a very common need.
This is done via diagAppertainsToDecl.



Comment at: clang/examples/Attribute/Attribute.cpp:35
+  }
+  virtual bool handleDeclAttribute(Sema &S, Decl *D,
+   const ParsedAttr &Attr) const {

aaron.ballman wrote:
> It is unclear to me how a user would add an attribute that needs to follow 
> the merge pattern we use in `mergeDeclAttribute()`.
I'm guessing it's probably not possible, from a quick look at 
mergeDeclAttribute.



Comment at: clang/examples/Attribute/Attribute.cpp:53
+  } else {
+S.Diag(ArgExpr->getExprLoc(), diag::err_attribute_argument_type)
+<< Attr.getAttrName() << AANT_ArgumentString;

aaron.ballman wrote:
> Do we have a way for plugin authors to introduce their own diagnostics, or 
> are they limited to just what diagnostics we already provide?
Custom diagnostics can be done with getCustomDiagID, and there's an example on 
line 54.


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[PATCH] D31343: Add an attribute plugin example

2020-02-27 Thread John Brawn via Phabricator via cfe-commits

john.brawn updated this revision to Diff 246989.
john.brawn marked an inline comment as done.
john.brawn added a comment.

Update based on review comments.


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Files:
  clang/examples/Attribute/Attribute.cpp
  clang/examples/Attribute/CMakeLists.txt
  clang/examples/CMakeLists.txt
  clang/test/CMakeLists.txt
  clang/test/Frontend/plugin-attribute.cpp

Index: clang/test/Frontend/plugin-attribute.cpp
===
--- /dev/null
+++ clang/test/Frontend/plugin-attribute.cpp
@@ -0,0 +1,25 @@
+// RUN: %clang -fplugin=%llvmshlibdir/Attribute%pluginext -emit-llvm -S %s -o - 2>&1 | FileCheck %s --check-prefix=ATTRIBUTE
+// RUN: not %clang -fplugin=%llvmshlibdir/Attribute%pluginext -emit-llvm -DBAD_ATTRIBUTE -S %s -o - 2>&1 | FileCheck %s --check-prefix=BADATTRIBUTE
+// REQUIRES: plugins, examples
+
+void fn1a() __attribute__((example)) { }
+[[example]] void fn1b() { }
+[[plugin::example]] void fn1c() { }
+void fn2() __attribute__((example("somestring"))) { }
+// ATTRIBUTE: warning: 'example' attribute only applies to functions
+int var1 __attribute__((example("otherstring"))) = 1;
+
+// ATTRIBUTE: [[STR1_VAR:@.+]] = private unnamed_addr constant [10 x i8] c"example()\00"
+// ATTRIBUTE: [[STR2_VAR:@.+]] = private unnamed_addr constant [20 x i8] c"example(somestring)\00"
+// ATTRIBUTE: @llvm.global.annotations = {{.*}}@{{.*}}fn1a{{.*}}[[STR1_VAR]]{{.*}}@{{.*}}fn1b{{.*}}[[STR1_VAR]]{{.*}}@{{.*}}fn1c{{.*}}[[STR1_VAR]]{{.*}}@{{.*}}fn2{{.*}}[[STR2_VAR]]
+
+#ifdef BAD_ATTRIBUTE
+class Example {
+  // BADATTRIBUTE: error: 'example' attribute only allowed at file scope
+  void __attribute__((example)) fn3();
+};
+// BADATTRIBUTE: error: 'example' attribute requires a string
+void fn4() __attribute__((example(123))) { }
+// BADATTRIBUTE: error: 'example' attribute takes no more than 1 argument
+void fn5() __attribute__((example("a","b"))) { }
+#endif
Index: clang/test/CMakeLists.txt
===
--- clang/test/CMakeLists.txt
+++ clang/test/CMakeLists.txt
@@ -72,6 +72,7 @@
 
 if (CLANG_BUILD_EXAMPLES)
   list(APPEND CLANG_TEST_DEPS
+Attribute
 AnnotateFunctions
 clang-interpreter
 PrintFunctionNames
Index: clang/examples/CMakeLists.txt
===
--- clang/examples/CMakeLists.txt
+++ clang/examples/CMakeLists.txt
@@ -6,3 +6,4 @@
 add_subdirectory(clang-interpreter)
 add_subdirectory(PrintFunctionNames)
 add_subdirectory(AnnotateFunctions)
+add_subdirectory(Attribute)
Index: clang/examples/Attribute/CMakeLists.txt
===
--- /dev/null
+++ clang/examples/Attribute/CMakeLists.txt
@@ -0,0 +1,11 @@
+add_llvm_library(Attribute MODULE Attribute.cpp PLUGIN_TOOL clang)
+
+if(LLVM_ENABLE_PLUGINS AND (WIN32 OR CYGWIN))
+  target_link_libraries(AnnotateFunctions ${cmake_2_8_12_PRIVATE}
+clangAST
+clangBasic
+clangFrontend
+clangLex
+LLVMSupport
+)
+endif()
Index: clang/examples/Attribute/Attribute.cpp
===
--- /dev/null
+++ clang/examples/Attribute/Attribute.cpp
@@ -0,0 +1,81 @@
+//===- Attribute.cpp --===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===--===//
+//
+// Example clang plugin which adds an an annotation to file-scope declarations
+// with the 'example' attribute.
+//
+//===--===//
+
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/Attr.h"
+#include "clang/Sema/ParsedAttr.h"
+#include "clang/Sema/Sema.h"
+#include "clang/Sema/SemaDiagnostic.h"
+#include "llvm/IR/Attributes.h"
+using namespace clang;
+
+namespace {
+
+struct ExampleAttrInfo : public ParsedAttrInfo {
+  ExampleAttrInfo() {
+// Set the kind to NoSemaHandlerAttribute to make sure clang doesn't assume
+// anything about what it does.
+AttrKind = ParsedAttr::NoSemaHandlerAttribute;
+// Can take an optional string argument (the check that the argument
+// actually is a string happens in handleDeclAttribute).
+OptArgs = 1;
+// GNU-style __attribute__(("example")) and C++-style [[example]] and
+// [[plugin::example]] supported.
+Spellings.push_back({ParsedAttr::AS_GNU, "example"});
+Spellings.push_back({ParsedAttr::AS_CXX11, "::example"});
+Spellings.push_back({ParsedAttr::AS_CXX11, "plugin::example"});
+  }
+
+  virtual bool diagAppertainsToDecl(Sema &S, const ParsedAttr &Attr,
+const Decl *D) const {
+//

[PATCH] D31343: Add an attribute plugin example

2020-02-05 Thread Sorawee Porncharoenwase via Phabricator via cfe-commits

sorawee added inline comments.



Comment at: clang/test/Frontend/plugin-attribute.cpp:16
+void fn3() {
+  // BADATTRIBUTE: error: 'example' attribute only allowed at file scop
+  int var2 __attribute__((example));

Typo: scope


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[PATCH] D31343: Add an attribute plugin example

2020-02-02 Thread Aaron Ballman via Phabricator via cfe-commits

aaron.ballman added inline comments.



Comment at: clang/examples/Attribute/Attribute.cpp:25
+struct ExampleAttrInfo : public ParsedAttrInfo {
+  ExampleAttrInfo() {
+// Set the kind to NoSemaHandlerAttribute to make sure clang doesn't assume

It would be really handy for the example to show how to list subjects for the 
declaration attribute, as that's a very common need.



Comment at: clang/examples/Attribute/Attribute.cpp:29
+AttrKind = ParsedAttr::NoSemaHandlerAttribute;
+// Can take an optional string argument.
+OptArgs = 1;

Nothing here suggests the argument must be a string. It would be ideal to show 
users how to list out arguments and their types.



Comment at: clang/examples/Attribute/Attribute.cpp:32-33
+// GNU-style __attribute__(("example")) and C++-style [[example]] 
supported.
+Spellings.push_back({ParsedAttr::AS_GNU, "example"});
+Spellings.push_back({ParsedAttr::AS_CXX11, "::example"});
+  }

Showing how to have a vendor namespace would also be especially helpful.

As a point of design, I wonder if we should be documenting (or diagnosing?) 
attributes from plugins that are added to the clang vendor namespace, as that 
does not seem like something we want to encourage?



Comment at: clang/examples/Attribute/Attribute.cpp:35
+  }
+  virtual bool handleDeclAttribute(Sema &S, Decl *D,
+   const ParsedAttr &Attr) const {

It is unclear to me how a user would add an attribute that needs to follow the 
merge pattern we use in `mergeDeclAttribute()`.



Comment at: clang/examples/Attribute/Attribute.cpp:53
+  } else {
+S.Diag(ArgExpr->getExprLoc(), diag::err_attribute_argument_type)
+<< Attr.getAttrName() << AANT_ArgumentString;

Do we have a way for plugin authors to introduce their own diagnostics, or are 
they limited to just what diagnostics we already provide?


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[PATCH] D31343: Add an attribute plugin example

2020-01-21 Thread John Brawn via Phabricator via cfe-commits

john.brawn updated this revision to Diff 239307.
john.brawn added reviewers: erichkeane, aaron.ballman, rjmccall.
john.brawn set the repository for this revision to rG LLVM Github Monorepo.
john.brawn added a subscriber: cfe-commits.
john.brawn added a comment.
Herald added a project: clang.

Resurrecting this old patch. This is the fourth of four patches to make it 
possible for clang plugins to define attributes.


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Files:
  clang/examples/Attribute/Attribute.cpp
  clang/examples/Attribute/CMakeLists.txt
  clang/examples/CMakeLists.txt
  clang/test/CMakeLists.txt
  clang/test/Frontend/plugin-attribute.cpp

Index: clang/test/Frontend/plugin-attribute.cpp
===
--- /dev/null
+++ clang/test/Frontend/plugin-attribute.cpp
@@ -0,0 +1,23 @@
+// RUN: %clang -fplugin=%llvmshlibdir/Attribute%pluginext -emit-llvm -S %s -o - | FileCheck %s --check-prefix=ATTRIBUTE
+// RUN: not %clang -fplugin=%llvmshlibdir/Attribute%pluginext -emit-llvm -DBAD_ATTRIBUTE -S %s -o - 2>&1 | FileCheck %s --check-prefix=BADATTRIBUTE
+// REQUIRES: plugins, examples
+
+// ATTRIBUTE: [[STR1_VAR:@.+]] = private unnamed_addr constant [10 x i8] c"example()\00"
+// ATTRIBUTE: [[STR2_VAR:@.+]] = private unnamed_addr constant [20 x i8] c"example(somestring)\00"
+// ATTRIBUTE: [[STR3_VAR:@.+]] = private unnamed_addr constant [21 x i8] c"example(otherstring)\00"
+// ATTRIBUTE: @llvm.global.annotations = {{.*}}@{{.*}}fn1a{{.*}}[[STR1_VAR]]{{.*}}@{{.*}}fn1b{{.*}}[[STR1_VAR]]{{.*}}@{{.*}}fn2{{.*}}[[STR2_VAR]]{{.*}}@{{.*}}var1{{.*}}[[STR3_VAR]]
+void fn1a() __attribute__((example)) { }
+[[example]] void fn1b() { }
+void fn2() __attribute__((example("somestring"))) { }
+int var1 __attribute__((example("otherstring"))) = 1;
+
+#ifdef BAD_ATTRIBUTE
+void fn3() {
+  // BADATTRIBUTE: error: 'example' attribute only allowed at file scop
+  int var2 __attribute__((example));
+}
+// BADATTRIBUTE: error: 'example' attribute requires a string
+void fn4() __attribute__((example(123))) { }
+// BADATTRIBUTE: error: 'example' attribute takes no more than 1 argument
+void fn5() __attribute__((example("a","b"))) { }
+#endif
Index: clang/test/CMakeLists.txt
===
--- clang/test/CMakeLists.txt
+++ clang/test/CMakeLists.txt
@@ -72,6 +72,7 @@
 
 if (CLANG_BUILD_EXAMPLES)
   list(APPEND CLANG_TEST_DEPS
+Attribute
 AnnotateFunctions
 clang-interpreter
 PrintFunctionNames
Index: clang/examples/CMakeLists.txt
===
--- clang/examples/CMakeLists.txt
+++ clang/examples/CMakeLists.txt
@@ -6,3 +6,4 @@
 add_subdirectory(clang-interpreter)
 add_subdirectory(PrintFunctionNames)
 add_subdirectory(AnnotateFunctions)
+add_subdirectory(Attribute)
Index: clang/examples/Attribute/CMakeLists.txt
===
--- /dev/null
+++ clang/examples/Attribute/CMakeLists.txt
@@ -0,0 +1,11 @@
+add_llvm_library(Attribute MODULE Attribute.cpp PLUGIN_TOOL clang)
+
+if(LLVM_ENABLE_PLUGINS AND (WIN32 OR CYGWIN))
+  target_link_libraries(AnnotateFunctions ${cmake_2_8_12_PRIVATE}
+clangAST
+clangBasic
+clangFrontend
+clangLex
+LLVMSupport
+)
+endif()
Index: clang/examples/Attribute/Attribute.cpp
===
--- /dev/null
+++ clang/examples/Attribute/Attribute.cpp
@@ -0,0 +1,66 @@
+//===- Attribute.cpp --===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===--===//
+//
+// Example clang plugin which adds an an annotation to file-scope declarations
+// with the 'example' attribute.
+//
+//===--===//
+
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/Attr.h"
+#include "clang/Sema/ParsedAttr.h"
+#include "clang/Sema/Sema.h"
+#include "clang/Sema/SemaDiagnostic.h"
+#include "llvm/IR/Attributes.h"
+using namespace clang;
+
+namespace {
+
+struct ExampleAttrInfo : public ParsedAttrInfo {
+  ExampleAttrInfo() {
+// Set the kind to NoSemaHandlerAttribute to make sure clang doesn't assume
+// anything about what it does.
+AttrKind = ParsedAttr::NoSemaHandlerAttribute;
+// Can take an optional string argument.
+OptArgs = 1;
+// GNU-style __attribute__(("example")) and C++-style [[example]] supported.
+Spellings.push_back({ParsedAttr::AS_GNU, "example"});
+Spellings.push_back({ParsedAttr::AS_CXX11, "::example"});
+  }
+  virtual bool handleDeclAttribute(Sema &S, Dec

[PATCH] D31343: Add an attribute plugin example

[PATCH] D31343: Add an attribute plugin example

[PATCH] D31343: Add an attribute plugin example

[PATCH] D31343: Add an attribute plugin example

[PATCH] D31343: Add an attribute plugin example

[PATCH] D31343: Add an attribute plugin example

[PATCH] D31343: Add an attribute plugin example

[PATCH] D31343: Add an attribute plugin example

[PATCH] D31343: Add an attribute plugin example

[PATCH] D31343: Add an attribute plugin example

[PATCH] D31343: Add an attribute plugin example

[PATCH] D31343: Add an attribute plugin example

[PATCH] D31343: Add an attribute plugin example

[PATCH] D31343: Add an attribute plugin example

[PATCH] D31343: Add an attribute plugin example

[PATCH] D31343: Add an attribute plugin example

[PATCH] D31343: Add an attribute plugin example

[PATCH] D31343: Add an attribute plugin example

[PATCH] D31343: Add an attribute plugin example

[PATCH] D31343: Add an attribute plugin example

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