[clang] [llvm] [SpecialCaseList] Use glob by default (PR #74809)

[Fangrui Song via cfe-commits]

https://github.com/MaskRay created https://github.com/llvm/llvm-project/pull/74809

https://reviews.llvm.org/D154014 addes glob support and enables it when
`#!special-case-list-v2` is the first line. This patch makes the glob
support the default (faster than regex after
https://reviews.llvm.org/D156046) and switches to the deprecated regex
support if `#!special-case-list-v1` is the first line.

I have surveyed many ignore lists. All ignore lists I find only use
basic `*` `.` and don't use regex metacharacters such as `(` and `)`.
(As neither `src:` nor `fun:` benefits from using regex.)
They are unaffected by the transition (with a caution that regex
`src:x/a.pb.*` matches `x/axpbx` but glob `src:x/a.pb.*` doesn't).

There is no deprecating warning. If a user finds
`#!special-case-list-v1`, they shall read that the old syntax is
deprecated.

Link: https://discourse.llvm.org/t/use-glob-instead-of-regex-for-specialcaselists/71666


>From e6d1325fcf66e0b13722edbe5f91d9c0674938cb Mon Sep 17 00:00:00 2001
From: Fangrui Song <i at maskray.me>
Date: Thu, 7 Dec 2023 21:17:24 -0800
Subject: [PATCH] [SpecialCaseList] Use glob by default

https://reviews.llvm.org/D154014 addes glob support and enables it when
`#!special-case-list-v2` is the first line. This patch makes the glob
support the default (faster than regex after
https://reviews.llvm.org/D156046) and switches to the deprecated regex
support if `#!special-case-list-v1` is the first line.

I have surveyed many ignore lists. All ignore lists I find only use
basic `*` `.` and don't use regex metacharacters such as `(` and `)`.
(As neither `src:` nor `fun:` benefits from using regex.)
They are unaffected by the transition (with a caution that regex
`src:x/a.pb.*` matches `x/axpbx` but glob `src:x/a.pb.*` doesn't).

There is no deprecating warning. If a user finds
`#!special-case-list-v1`, they shall read that the old syntax is
deprecated.

Link: https://discourse.llvm.org/t/use-glob-instead-of-regex-for-specialcaselists/71666
---
 clang/docs/SanitizerSpecialCaseList.rst        | 18 +++++++++++-------
 llvm/lib/Support/SpecialCaseList.cpp           | 11 +++++------
 llvm/unittests/Support/SpecialCaseListTest.cpp |  8 ++++----
 3 files changed, 20 insertions(+), 17 deletions(-)

diff --git a/clang/docs/SanitizerSpecialCaseList.rst b/clang/docs/SanitizerSpecialCaseList.rst
index ab39276b04395..c7fb0fa3f8a82 100644
--- a/clang/docs/SanitizerSpecialCaseList.rst
+++ b/clang/docs/SanitizerSpecialCaseList.rst
@@ -56,13 +56,18 @@ and lines starting with "#" are ignored.
 
 .. note::
 
-  In `D154014 <https://reviews.llvm.org/D154014>`_ we transitioned to using globs instead
-  of regexes to match patterns in special case lists. Since this was a
-  breaking change, we will temporarily support the original behavior using
-  regexes. If ``#!special-case-list-v2`` is the first line of the file, then
-  we will use the new behavior using globs. For more details, see
-  `this discourse post <https://discourse.llvm.org/t/use-glob-instead-of-regex-for-specialcaselists/71666>`_.
+  Prior to Clang 18, section names and entries described below use a variant of
+  regex where ``*`` is translated to ``.*``. Clang 18 (`D154014
+  <https://reviews.llvm.org/D154014>`) switches to glob and plans to remove
+  regex support in Clang 19.
 
+  For Clang 18, regex is supported if ``#!special-case-list-v1`` is the first
+  line of the file.
+
+  Many special case lists use ``.`` to indicate the literal character and do
+  not use regex metacharacters such as ``(``, ``)``. They are unaffected by the
+  regex to glob transition. For more details, see `this discourse post
+  <https://discourse.llvm.org/t/use-glob-instead-of-regex-for-specialcaselists/71666>`_.
 
 Section names are globs written in square brackets that denote
 which sanitizer the following entries apply to. For example, ``[address]``
@@ -80,7 +85,6 @@ tool-specific docs.
 
 .. code-block:: bash
 
-    #!special-case-list-v2
     # The line above is explained in the note above
     # Lines starting with # are ignored.
     # Turn off checks for the source file
diff --git a/llvm/lib/Support/SpecialCaseList.cpp b/llvm/lib/Support/SpecialCaseList.cpp
index ac8877cca8bc6..7a23421eaeb89 100644
--- a/llvm/lib/Support/SpecialCaseList.cpp
+++ b/llvm/lib/Support/SpecialCaseList.cpp
@@ -150,13 +150,12 @@ bool SpecialCaseList::parse(const MemoryBuffer *MB, std::string &Error) {
     return false;
   }
 
-  // In https://reviews.llvm.org/D154014 we transitioned to using globs instead
-  // of regexes to match patterns in special case lists. Since this was a
-  // breaking change, we will temporarily support the original behavior using
-  // regexes. If "#!special-case-list-v2" is the first line of the file, then
-  // we will use the new behavior using globs. For more details, see
+  // In https://reviews.llvm.org/D154014 we added glob support and planned to
+  // remove regex support in patterns. We temporarily support the original
+  // behavior using regexes if "#!special-case-list-v1" is the first line of the
+  // file. For more details, see
   // https://discourse.llvm.org/t/use-glob-instead-of-regex-for-specialcaselists/71666
-  bool UseGlobs = MB->getBuffer().starts_with("#!special-case-list-v2\n");
+  bool UseGlobs = !MB->getBuffer().starts_with("#!special-case-list-v1\n");
 
   for (line_iterator LineIt(*MB, /*SkipBlanks=*/true, /*CommentMarker=*/'#');
        !LineIt.is_at_eof(); LineIt++) {
diff --git a/llvm/unittests/Support/SpecialCaseListTest.cpp b/llvm/unittests/Support/SpecialCaseListTest.cpp
index 81faeca5d6357..725d20a9b4def 100644
--- a/llvm/unittests/Support/SpecialCaseListTest.cpp
+++ b/llvm/unittests/Support/SpecialCaseListTest.cpp
@@ -25,8 +25,8 @@ class SpecialCaseListTest : public ::testing::Test {
                                                        std::string &Error,
                                                        bool UseGlobs = true) {
     auto S = List.str();
-    if (UseGlobs)
-      S = (Twine("#!special-case-list-v2\n") + S).str();
+    if (!UseGlobs)
+      S = (Twine("#!special-case-list-v1\n") + S).str();
     std::unique_ptr<MemoryBuffer> MB = MemoryBuffer::getMemBuffer(S);
     return SpecialCaseList::create(MB.get(), Error);
   }
@@ -46,8 +46,8 @@ class SpecialCaseListTest : public ::testing::Test {
     SmallString<64> Path;
     sys::fs::createTemporaryFile("SpecialCaseListTest", "temp", FD, Path);
     raw_fd_ostream OF(FD, true, true);
-    if (UseGlobs)
-      OF << "#!special-case-list-v2\n";
+    if (!UseGlobs)
+      OF << "#!special-case-list-v1\n";
     OF << Contents;
     OF.close();
     return std::string(Path.str());