[PATCH] D75461: Ignore macro expansions when scanning for fallthrough comments
Timm Bäder via Phabricator via cfe-commits
cfe-commits at lists.llvm.org
Mon Mar 2 08:12:05 PST 2020
tbaeder created this revision.
tbaeder added a reviewer: tstellar.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.
When scanning for fallthrough comments, it's not useful to go to the definition of a macro. We instead only want to search at the expanded source code location. Includes a test that failed before.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D75461
Files:
clang/lib/Sema/AnalysisBasedWarnings.cpp
clang/test/Sema/fallthrough-comment.c
Index: clang/test/Sema/fallthrough-comment.c
===================================================================
--- clang/test/Sema/fallthrough-comment.c
+++ clang/test/Sema/fallthrough-comment.c
@@ -1,5 +1,7 @@
// RUN: %clang_cc1 -fsyntax-only -std=c11 -verify -Wimplicit-fallthrough %s
+#define SOME_CONSTANT 1
+
int fallthrough_comment(int n) {
switch (n) {
case 0:
@@ -10,9 +12,13 @@
/*fall-through.*/
- case 2:
+ case 3:
+ n += SOME_CONSTANT;
+ /* FALL THRU */
+
+ case 4:
n++;
- case 3: // expected-warning{{unannotated fall-through between switch labels}} expected-note{{insert '__attribute__((fallthrough));' to silence this warning}} expected-note{{insert 'break;' to avoid fall-through}}
+ case 5: // expected-warning{{unannotated fall-through between switch labels}} expected-note{{insert '__attribute__((fallthrough));' to silence this warning}} expected-note{{insert 'break;' to avoid fall-through}}
n++;
break;
}
Index: clang/lib/Sema/AnalysisBasedWarnings.cpp
===================================================================
--- clang/lib/Sema/AnalysisBasedWarnings.cpp
+++ clang/lib/Sema/AnalysisBasedWarnings.cpp
@@ -1216,9 +1216,10 @@
bool isFollowedByFallThroughComment(const Stmt *Statement) {
// Try to detect whether the fallthough is marked by a comment like
// /*FALLTHOUGH*/.
+ auto Loc = S.getSourceManager().getExpansionLoc(Statement->getEndLoc());
bool Invalid;
- const char *SourceData = S.getSourceManager().getCharacterData(
- Statement->getEndLoc(), &Invalid);
+ const char *SourceData =
+ S.getSourceManager().getCharacterData(Loc, &Invalid);
if (Invalid)
return false;
const char *LineStart = SourceData;
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