xbolva00 created this revision.
xbolva00 added reviewers: aaron.ballman, rsmith, rjmccall.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.
Detects unreachable statements in switches. GCC supports this warning too, on
by default.
Repository:
rC Clang
https://reviews.llvm.org/D63139
Files:
include/clang/Basic/DiagnosticGroups.td
include/clang/Basic/DiagnosticSemaKinds.td
lib/Sema/SemaStmt.cpp
test/Sema/switch_unreachable.c
test/SemaCXX/switch_unreachable.cpp
Index: test/SemaCXX/switch_unreachable.cpp
===================================================================
--- test/SemaCXX/switch_unreachable.cpp
+++ test/SemaCXX/switch_unreachable.cpp
@@ -0,0 +1,103 @@
+// RUN: %clang_cc1 -x c++ -fsyntax-only -verify -Wswitch-unreachable %s
+// RUN: %clang_cc1 -x c++ -fsyntax-only -verify -Wall %s
+
+void g(int x);
+
+void foo(int x) {
+ int b = 0;
+ if (x == 7)
+ goto label;
+ if (x == 3)
+ goto label2;
+ if (x == 4)
+ goto label3;
+ if (x == 1)
+ goto label4;
+
+ switch (x) {
+ label:
+ case 4:
+ break;
+ default:
+ return;
+ }
+
+ switch (x) {
+ x++; // expected-warning {{statement will be never executed}}
+ label2:
+ case 4:
+ break;
+ default:
+ return;
+ }
+
+ switch (x) {
+ label3:
+ x++;
+ case 4:
+ break;
+ default:
+ return;
+ }
+
+ switch (x) {
+ case 4:
+ return;
+ }
+
+ switch (x) {
+ b = x; // expected-warning {{statement will be never executed}}
+ case 7:
+ g(b);
+ break;
+ }
+
+ switch (x) {
+ break; // expected-warning {{statement will be never executed}}
+ case 7:
+ break;
+ }
+
+ switch (x) {
+ return; // expected-warning {{statement will be never executed}}
+ case 7:
+ break;
+ }
+
+ switch (x) {
+ x++; // expected-warning {{statement will be never executed}}
+ g(x); // expected-warning {{statement will be never executed}}
+ case 7:
+ break;
+ }
+
+ switch (x) {
+ x++; // expected-warning {{statement will be never executed}}
+ label4:
+ g(x);
+ case 7:
+ break;
+ }
+
+ switch (x) {
+ g(x); // expected-warning {{statement will be never executed}}
+ case 7:
+ break;
+ }
+
+ switch (x) {
+ g(x); // expected-warning {{statement will be never executed}}
+ case 1:
+ break;
+ case 2:
+ break;
+ }
+
+ switch (x) {
+ g(x); // expected-warning {{statement will be never executed}}
+ case 1:
+ case 2:
+ case 3:
+ break;
+ }
+}
Index: test/Sema/switch_unreachable.c
===================================================================
--- test/Sema/switch_unreachable.c
+++ test/Sema/switch_unreachable.c
@@ -0,0 +1,97 @@
+// RUN: %clang_cc1 -x c -fsyntax-only -verify -Wswitch-unreachable %s
+// RUN: %clang_cc1 -x c -fsyntax-only -verify -Wall %s
+
+void g(int x);
+
+void foo(int x) {
+ int b = 0;
+ if (x == 7)
+ goto label;
+ if (x == 3)
+ goto label2;
+ if (x == 4)
+ goto label3;
+ if (x == 1)
+ goto label4;
+
+ switch (x) {
+ label:
+ case 4:
+ break;
+ default:
+ return;
+ }
+
+ switch (x) {
+ x++; // expected-warning {{statement will be never executed}}
+ label2:
+ case 4:
+ break;
+ default:
+ return;
+ }
+
+ switch (x) {
+ label3:
+ x++;
+ case 4:
+ break;
+ default:
+ return;
+ }
+
+ switch (x) {
+ case 4:
+ return;
+ }
+
+ switch (x) {
+ b = x; // expected-warning {{statement will be never executed}}
+ case 7:
+ g(b);
+ break;
+ }
+
+ switch (x) {
+ break; // expected-warning {{statement will be never executed}}
+ case 7:
+ break;
+ }
+
+ switch (x) {
+ return; // expected-warning {{statement will be never executed}}
+ case 7:
+ break;
+ }
+
+ switch (x) {
+ x++; // expected-warning {{statement will be never executed}}
+ g(x); // expected-warning {{statement will be never executed}}
+ case 7:
+ break;
+ }
+
+ switch (x) {
+ x++; // expected-warning {{statement will be never executed}}
+ label4:
+ g(x);
+ case 7:
+ break;
+ }
+
+ switch (x) {
+ g(x); // expected-warning {{statement will be never executed}}
+ case 1:
+ break;
+ case 2:
+ break;
+ }
+
+ switch (x) {
+ g(x); // expected-warning {{statement will be never executed}}
+ case 1:
+ case 2:
+ case 3:
+ break;
+ }
+}
Index: lib/Sema/SemaStmt.cpp
===================================================================
--- lib/Sema/SemaStmt.cpp
+++ lib/Sema/SemaStmt.cpp
@@ -861,6 +861,16 @@
typedef std::vector<std::pair<llvm::APSInt, CaseStmt*> > CaseRangesTy;
CaseRangesTy CaseRanges;
+ CompoundStmt *CS = dyn_cast<CompoundStmt>(BodyStmt);
+ if (CS && !CS->body_empty()) {
+ for (auto It = CS->body_begin(); It != CS->body_end(); ++It) {
+ auto *S = *It;
+ if (isa<LabelStmt>(S) || isa<CaseStmt>(S) || isa<DefaultStmt>(S))
+ break;
+ Diag(S->getBeginLoc(), diag::warn_unreachable_stmt_in_switch);
+ }
+ }
+
DefaultStmt *TheDefaultStmt = nullptr;
bool CaseListIsErroneous = false;
Index: include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- include/clang/Basic/DiagnosticSemaKinds.td
+++ include/clang/Basic/DiagnosticSemaKinds.td
@@ -8188,6 +8188,8 @@
def err_default_not_in_switch : Error<
"'default' statement not in switch statement">;
def err_case_not_in_switch : Error<"'case' statement not in switch statement">;
+def warn_unreachable_stmt_in_switch : Warning<
+ "statement will be never executed">, InGroup<SwitchUnreachable>, DefaultIgnore;
def warn_bool_switch_condition : Warning<
"switch condition has boolean value">, InGroup<SwitchBool>;
def warn_case_value_overflow : Warning<
Index: include/clang/Basic/DiagnosticGroups.td
===================================================================
--- include/clang/Basic/DiagnosticGroups.td
+++ include/clang/Basic/DiagnosticGroups.td
@@ -538,6 +538,7 @@
def CoveredSwitchDefault : DiagGroup<"covered-switch-default">;
def SwitchBool : DiagGroup<"switch-bool">;
def SwitchEnum : DiagGroup<"switch-enum">;
+def SwitchUnreachable : DiagGroup<"switch-unreachable">;
def Switch : DiagGroup<"switch">;
def EnumCompareSwitch : DiagGroup<"enum-compare-switch">;
def EnumCompare : DiagGroup<"enum-compare", [EnumCompareSwitch]>;
@@ -842,7 +843,7 @@
// Note that putting warnings in -Wall will not disable them by default. If a
// warning should be active _only_ when -Wall is passed in, mark it as
// DefaultIgnore in addition to putting it here.
-def All : DiagGroup<"all", [Most, Parentheses, Switch, SwitchBool]>;
+def All : DiagGroup<"all", [Most, Parentheses, Switch, SwitchBool, SwitchUnreachable]>;
// Warnings that should be in clang-cl /w4.
def : DiagGroup<"CL4", [All, Extra]>;
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