[Clang] Do not warn for serialized builtin or command-line definitions #137306
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…d-line definitions
When using -dD to generte a preprocessed output, the #define directives are preserved. This includes builtin and command line definitions. Before, clang would warn for reserved identifiers for serialzied builtin and command-line definitions. This patch adds an exception to these cases.
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@llvm/pr-subscribers-clang Author: Juan Manuel Martinez Caamaño (jmmartinez) ChangesWhen using Before, clang would warn for reserved identifiers for serialized built-in Full diff: https://github.com/llvm/llvm-project/pull/137306.diff 2 Files Affected:
diff --git a/clang/lib/Lex/PPDirectives.cpp b/clang/lib/Lex/PPDirectives.cpp
index 6c337801a8435..6468e62889413 100644
--- a/clang/lib/Lex/PPDirectives.cpp
+++ b/clang/lib/Lex/PPDirectives.cpp
@@ -371,8 +371,12 @@ bool Preprocessor::CheckMacroName(Token &MacroNameTok, MacroUse isDefineUndef,
SourceLocation MacroNameLoc = MacroNameTok.getLocation();
if (ShadowFlag)
*ShadowFlag = false;
- if (!SourceMgr.isInSystemHeader(MacroNameLoc) &&
- (SourceMgr.getBufferName(MacroNameLoc) != "<built-in>")) {
+ // Macro names with reserved identifiers are accepted if built-in or passed
+ // through the command line (the later may be present if -dD was used to
+ // generate the preprocessed file).
+ bool IsBuiltinOrCmd = SourceMgr.isWrittenInBuiltinFile(MacroNameLoc) ||
+ SourceMgr.isWrittenInCommandLineFile(MacroNameLoc);
+ if (!IsBuiltinOrCmd && !SourceMgr.isInSystemHeader(MacroNameLoc)) {
MacroDiag D = MD_NoWarn;
if (isDefineUndef == MU_Define) {
D = shouldWarnOnMacroDef(*this, II);
diff --git a/clang/test/Preprocessor/macro_reserved.i b/clang/test/Preprocessor/macro_reserved.i
new file mode 100644
index 0000000000000..c9ed044e4c931
--- /dev/null
+++ b/clang/test/Preprocessor/macro_reserved.i
@@ -0,0 +1,11 @@
+// RUN: %clang_cc1 -fsyntax-only -verify -x cpp-output %s
+#pragma clang diagnostic push
+#pragma clang diagnostic warning "-Wreserved-macro-identifier"
+# 1 "<built-in>" 1
+#define __BUILTIN__
+# 2 "<command line>" 1
+#define __CMD__
+# 3 "biz.cpp" 1
+#define __SOME_FILE__ // expected-warning {{macro name is a reserved identifier}}
+int v;
+#pragma clang diagnostic pop
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Thanks ! |
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/197/builds/4754 Here is the relevant piece of the build log for the reference |
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This has a large negative compile-time impact, esp for unoptimized builds: https://llvm-compile-time-tracker.com/compare.php?from=7ec1e0f7ba9f3b03fa6163ab62c17dc9b404303e&to=0d3d2f639c42b22fc1b9453c7b834dbb0f16c0dc&stat=instructions:u |
nikic
reviewed
May 1, 2025
| // through the command line (the later may be present if -dD was used to | ||
| // generate the preprocessed file). | ||
| bool IsBuiltinOrCmd = SourceMgr.isWrittenInBuiltinFile(MacroNameLoc) || | ||
| SourceMgr.isWrittenInCommandLineFile(MacroNameLoc); |
There was a problem hiding this comment.
Can at least combine these to avoid the duplicate getPresumedLoc(), but possibly these can be more efficient in general? E.g. isInSystemHeader has a much more optimized implementation.
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@jmmartinez Ping. |
IanWood1
pushed a commit
to IanWood1/llvm-project
that referenced
this pull request
May 6, 2025
llvm#137306) When using `-dD` to generate a preprocessed output, the `#define` directives are preserved. This includes built-in and command-line definitions. Before, clang would warn for reserved identifiers for serialized built-in and command-line definitions. This patch adds an exception to these cases.
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Yeah, those perf drops are pretty unfortunate. Nikita's idea of trying to combine the checks makes sense to me as a good approach to try. |
IanWood1
pushed a commit
to IanWood1/llvm-project
that referenced
this pull request
May 6, 2025
llvm#137306) When using `-dD` to generate a preprocessed output, the `#define` directives are preserved. This includes built-in and command-line definitions. Before, clang would warn for reserved identifiers for serialized built-in and command-line definitions. This patch adds an exception to these cases.
IanWood1
pushed a commit
to IanWood1/llvm-project
that referenced
this pull request
May 6, 2025
llvm#137306) When using `-dD` to generate a preprocessed output, the `#define` directives are preserved. This includes built-in and command-line definitions. Before, clang would warn for reserved identifiers for serialized built-in and command-line definitions. This patch adds an exception to these cases.
GeorgeARM
pushed a commit
to GeorgeARM/llvm-project
that referenced
this pull request
May 7, 2025
llvm#137306) When using `-dD` to generate a preprocessed output, the `#define` directives are preserved. This includes built-in and command-line definitions. Before, clang would warn for reserved identifiers for serialized built-in and command-line definitions. This patch adds an exception to these cases.
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When using
-dDto generate a preprocessed output, the#definedirectivesare preserved. This includes built-in and command-line definitions.
Before, clang would warn for reserved identifiers for serialized built-in
and command-line definitions.
This patch adds an exception to these cases.