In response to some discussions on IRC, tweak the wording of the new
-Wsometimes-uninitialized diagnostics to make it clearer that the cause
of the issue may be a condition which must always evaluate to true or
false, rather than an uninitialized variable.
To emphasize this, add a new note with a fixit which removes the
impossible condition or replaces it with a constant.
Also, downgrade the diagnostic from -Wsometimes-uninitialized to
-Wconditional-uninitialized when it applies to a range-based for loop,
since the condition is not written explicitly in the code in that case.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@157511 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/AnalysisBasedWarnings.cpp b/lib/Sema/AnalysisBasedWarnings.cpp
index 562fe68..8f16e70 100644
--- a/lib/Sema/AnalysisBasedWarnings.cpp
+++ b/lib/Sema/AnalysisBasedWarnings.cpp
@@ -19,6 +19,7 @@
#include "clang/Basic/SourceManager.h"
#include "clang/Basic/SourceLocation.h"
#include "clang/Lex/Preprocessor.h"
+#include "clang/Lex/Lexer.h"
#include "clang/AST/DeclObjC.h"
#include "clang/AST/DeclCXX.h"
#include "clang/AST/ExprObjC.h"
@@ -456,31 +457,92 @@
return true;
}
-/// NoteUninitBranches -- Helper function to produce notes for branches which
-/// inevitably lead to an uninitialized variable use.
-static void NoteUninitBranches(Sema &S, const UninitUse &Use) {
+/// Create a fixit to remove an if-like statement, on the assumption that its
+/// condition is CondVal.
+static void CreateIfFixit(Sema &S, const Stmt *If, const Stmt *Then,
+ const Stmt *Else, bool CondVal,
+ FixItHint &Fixit1, FixItHint &Fixit2) {
+ if (CondVal) {
+ // If condition is always true, remove all but the 'then'.
+ Fixit1 = FixItHint::CreateRemoval(
+ CharSourceRange::getCharRange(If->getLocStart(),
+ Then->getLocStart()));
+ if (Else) {
+ SourceLocation ElseKwLoc = Lexer::getLocForEndOfToken(
+ Then->getLocEnd(), 0, S.getSourceManager(), S.getLangOpts());
+ Fixit2 = FixItHint::CreateRemoval(
+ SourceRange(ElseKwLoc, Else->getLocEnd()));
+ }
+ } else {
+ // If condition is always false, remove all but the 'else'.
+ if (Else)
+ Fixit1 = FixItHint::CreateRemoval(
+ CharSourceRange::getCharRange(If->getLocStart(),
+ Else->getLocStart()));
+ else
+ Fixit1 = FixItHint::CreateRemoval(If->getSourceRange());
+ }
+}
+
+/// DiagUninitUse -- Helper function to produce a diagnostic for an
+/// uninitialized use of a variable.
+static void DiagUninitUse(Sema &S, const VarDecl *VD, const UninitUse &Use,
+ bool IsCapturedByBlock) {
+ bool Diagnosed = false;
+
+ // Diagnose each branch which leads to a sometimes-uninitialized use.
for (UninitUse::branch_iterator I = Use.branch_begin(), E = Use.branch_end();
I != E; ++I) {
+ assert(Use.getKind() == UninitUse::Sometimes);
+
+ const Expr *User = Use.getUser();
const Stmt *Term = I->Terminator;
+
+ // Information used when building the diagnostic.
unsigned DiagKind;
- SourceRange Range;
const char *Str;
+ SourceRange Range;
+
+ // FixIts to suppress the diagnosic by removing the dead condition.
+ // For all binary terminators, branch 0 is taken if the condition is true,
+ // and branch 1 is taken if the condition is false.
+ int RemoveDiagKind = -1;
+ const char *FixitStr =
+ S.getLangOpts().CPlusPlus ? (I->Output ? "true" : "false")
+ : (I->Output ? "1" : "0");
+ FixItHint Fixit1, Fixit2;
+
switch (Term->getStmtClass()) {
default:
- // Don't know how to report this.
+ // Don't know how to report this. Just fall back to 'may be used
+ // uninitialized'. This happens for range-based for, which the user
+ // can't explicitly fix.
+ // FIXME: This also happens if the first use of a variable is always
+ // uninitialized, eg "for (int n; n < 10; ++n)". We should report that
+ // with the 'is uninitialized' diagnostic.
continue;
// "condition is true / condition is false".
- case Stmt::IfStmtClass:
+ case Stmt::IfStmtClass: {
+ const IfStmt *IS = cast<IfStmt>(Term);
DiagKind = 0;
Str = "if";
- Range = cast<IfStmt>(Term)->getCond()->getSourceRange();
+ Range = IS->getCond()->getSourceRange();
+ RemoveDiagKind = 0;
+ CreateIfFixit(S, IS, IS->getThen(), IS->getElse(),
+ I->Output, Fixit1, Fixit2);
break;
- case Stmt::ConditionalOperatorClass:
+ }
+ case Stmt::ConditionalOperatorClass: {
+ const ConditionalOperator *CO = cast<ConditionalOperator>(Term);
DiagKind = 0;
Str = "?:";
- Range = cast<ConditionalOperator>(Term)->getCond()->getSourceRange();
+ Range = CO->getCond()->getSourceRange();
+ RemoveDiagKind = 0;
+ CreateIfFixit(S, CO, CO->getTrueExpr(), CO->getFalseExpr(),
+ I->Output, Fixit1, Fixit2);
break;
+ }
case Stmt::BinaryOperatorClass: {
const BinaryOperator *BO = cast<BinaryOperator>(Term);
if (!BO->isLogicalOp())
@@ -488,6 +550,15 @@
DiagKind = 0;
Str = BO->getOpcodeStr();
Range = BO->getLHS()->getSourceRange();
+ RemoveDiagKind = 0;
+ if ((BO->getOpcode() == BO_LAnd && I->Output) ||
+ (BO->getOpcode() == BO_LOr && !I->Output))
+ // true && y -> y, false || y -> y.
+ Fixit1 = FixItHint::CreateRemoval(SourceRange(BO->getLocStart(),
+ BO->getOperatorLoc()));
+ else
+ // false && y -> false, true || y -> true.
+ Fixit1 = FixItHint::CreateReplacement(BO->getSourceRange(), FixitStr);
break;
}
@@ -496,16 +567,18 @@
DiagKind = 1;
Str = "while";
Range = cast<WhileStmt>(Term)->getCond()->getSourceRange();
+ RemoveDiagKind = 1;
+ Fixit1 = FixItHint::CreateReplacement(Range, FixitStr);
break;
case Stmt::ForStmtClass:
DiagKind = 1;
Str = "for";
Range = cast<ForStmt>(Term)->getCond()->getSourceRange();
- break;
- case Stmt::CXXForRangeStmtClass:
- DiagKind = 1;
- Str = "for";
- Range = cast<CXXForRangeStmt>(Term)->getCond()->getSourceRange();
+ RemoveDiagKind = 1;
+ if (I->Output)
+ Fixit1 = FixItHint::CreateRemoval(Range);
+ else
+ Fixit1 = FixItHint::CreateReplacement(Range, FixitStr);
break;
// "condition is true / loop is exited".
@@ -513,6 +586,8 @@
DiagKind = 2;
Str = "do";
Range = cast<DoStmt>(Term)->getCond()->getSourceRange();
+ RemoveDiagKind = 1;
+ Fixit1 = FixItHint::CreateReplacement(Range, FixitStr);
break;
// "switch case is taken".
@@ -528,9 +603,24 @@
break;
}
- S.Diag(Range.getBegin(), diag::note_sometimes_uninit_var_branch)
- << DiagKind << Str << I->Output << Range;
+ S.Diag(Range.getBegin(), diag::warn_sometimes_uninit_var)
+ << VD->getDeclName() << IsCapturedByBlock << DiagKind
+ << Str << I->Output << Range;
+ S.Diag(User->getLocStart(), diag::note_uninit_var_use)
+ << IsCapturedByBlock << User->getSourceRange();
+ if (RemoveDiagKind != -1)
+ S.Diag(Fixit1.RemoveRange.getBegin(), diag::note_uninit_fixit_remove_cond)
+ << RemoveDiagKind << Str << I->Output << Fixit1 << Fixit2;
+
+ Diagnosed = true;
}
+
+ if (!Diagnosed)
+ S.Diag(Use.getUser()->getLocStart(),
+ Use.getKind() == UninitUse::Always ? diag::warn_uninit_var
+ : diag::warn_maybe_uninit_var)
+ << VD->getDeclName() << IsCapturedByBlock
+ << Use.getUser()->getSourceRange();
}
/// DiagnoseUninitializedUse -- Helper function for diagnosing uses of an
@@ -568,37 +658,15 @@
}
}
- unsigned DiagID = 0;
- switch (Use.getKind()) {
- case UninitUse::Always: DiagID = diag::warn_uninit_var; break;
- case UninitUse::Sometimes: DiagID = diag::warn_sometimes_uninit_var; break;
- case UninitUse::Maybe: DiagID = diag::warn_maybe_uninit_var; break;
- }
- S.Diag(DRE->getLocStart(), DiagID)
- << VD->getDeclName() << DRE->getSourceRange();
- NoteUninitBranches(S, Use);
+ DiagUninitUse(S, VD, Use, false);
} else {
const BlockExpr *BE = cast<BlockExpr>(Use.getUser());
- if (VD->getType()->isBlockPointerType() &&
- !VD->hasAttr<BlocksAttr>())
- S.Diag(BE->getLocStart(), diag::warn_uninit_byref_blockvar_captured_by_block)
+ if (VD->getType()->isBlockPointerType() && !VD->hasAttr<BlocksAttr>())
+ S.Diag(BE->getLocStart(),
+ diag::warn_uninit_byref_blockvar_captured_by_block)
<< VD->getDeclName();
- else {
- unsigned DiagID = 0;
- switch (Use.getKind()) {
- case UninitUse::Always:
- DiagID = diag::warn_uninit_var_captured_by_block;
- break;
- case UninitUse::Sometimes:
- DiagID = diag::warn_sometimes_uninit_var_captured_by_block;
- break;
- case UninitUse::Maybe:
- DiagID = diag::warn_maybe_uninit_var_captured_by_block;
- break;
- }
- S.Diag(BE->getLocStart(), DiagID) << VD->getDeclName();
- NoteUninitBranches(S, Use);
- }
+ else
+ DiagUninitUse(S, VD, Use, true);
}
// Report where the variable was declared when the use wasn't within