From 09f15f3edf1bd324d0eef465edd5d0bdedcb84b3 Mon Sep 17 00:00:00 2001 From: Alexander Kornienko Date: Fri, 25 Jan 2013 20:44:56 +0000 Subject: [PATCH] Silence unintended fallthrough diagnostic on a case label preceded with a normal label. Summary: It's unlikely that a fallthrough is unintended in the following code: switch (n) { ... label: case 1: ... goto label; ... } Reviewers: rsmith, doug.gregor Reviewed By: doug.gregor CC: cfe-commits Differential Revision: http://llvm-reviews.chandlerc.com/D329 llvm-svn: 173486 --- clang/lib/Sema/AnalysisBasedWarnings.cpp | 4 ++++ clang/test/SemaCXX/switch-implicit-fallthrough.cpp | 12 ++++++++++++ 2 files changed, 16 insertions(+) diff --git a/clang/lib/Sema/AnalysisBasedWarnings.cpp b/clang/lib/Sema/AnalysisBasedWarnings.cpp index 78864ec..1687f69 100644 --- a/clang/lib/Sema/AnalysisBasedWarnings.cpp +++ b/clang/lib/Sema/AnalysisBasedWarnings.cpp @@ -722,6 +722,10 @@ namespace { if (SW && SW->getSubStmt() == B.getLabel() && P->begin() == P->end()) continue; // Previous case label has no statements, good. + const LabelStmt *L = dyn_cast_or_null(P->getLabel()); + if (L && L->getSubStmt() == B.getLabel() && P->begin() == P->end()) + continue; // Case label is preceded with a normal label, good. + if (P->pred_begin() == P->pred_end()) { // The block is unreachable. // This only catches trivially unreachable blocks. for (CFGBlock::const_iterator ElIt = P->begin(), ElEnd = P->end(); diff --git a/clang/test/SemaCXX/switch-implicit-fallthrough.cpp b/clang/test/SemaCXX/switch-implicit-fallthrough.cpp index 75dda8a..93e724e 100644 --- a/clang/test/SemaCXX/switch-implicit-fallthrough.cpp +++ b/clang/test/SemaCXX/switch-implicit-fallthrough.cpp @@ -38,6 +38,18 @@ int fallthrough(int n) { case 68: break; } + switch (n / 15) { +label_case_70: + case 70: + n += 333; + break; + case 71: + n += 334; + goto label_case_70; + case 72: + n += 335; + break; + } switch (n / 20) { case 7: n += 400; -- 2.7.4