[clang-tidy] Fixes to readability-implicit-bool-conversion (#72050)

- Fixed issue with invalid code being generated when static_cast is put
into fix, and no space were added before it.
- Fixed issue with duplicate parentheses being added when double
implicit cast is used.

Closes #71848

clang-tools-extra/clang-tidy/readability/ImplicitBoolConversionCheck.cpp

@@ -151,16 +151,29 @@ StringRef getEquivalentBoolLiteralForExpr(const Expr *Expression,
   return {};
 }
 
+bool needsSpacePrefix(SourceLocation Loc, ASTContext &Context) {
+  SourceRange PrefixRange(Loc.getLocWithOffset(-1), Loc);
+  StringRef SpaceBeforeStmtStr = Lexer::getSourceText(
+      CharSourceRange::getCharRange(PrefixRange), Context.getSourceManager(),
+      Context.getLangOpts(), nullptr);
+  if (SpaceBeforeStmtStr.empty())
+    return true;
+
+  const StringRef AllowedCharacters(" \t\n\v\f\r(){}[]<>;,+=-|&~!^*/");
+  return !AllowedCharacters.contains(SpaceBeforeStmtStr.back());
+}
+
 void fixGenericExprCastFromBool(DiagnosticBuilder &Diag,
                                 const ImplicitCastExpr *Cast,
                                 ASTContext &Context, StringRef OtherType) {
   const Expr *SubExpr = Cast->getSubExpr();
-  bool NeedParens = !isa<ParenExpr>(SubExpr);
+  const bool NeedParens = !isa<ParenExpr>(SubExpr->IgnoreImplicit());
+  const bool NeedSpace = needsSpacePrefix(Cast->getBeginLoc(), Context);
 
   Diag << FixItHint::CreateInsertion(
-      Cast->getBeginLoc(),
-      (Twine("static_cast<") + OtherType + ">" + (NeedParens ? "(" : ""))
-          .str());
+      Cast->getBeginLoc(), (Twine() + (NeedSpace ? " " : "") + "static_cast<" +
+                            OtherType + ">" + (NeedParens ? "(" : ""))
+                               .str());
 
   if (NeedParens) {
     SourceLocation EndLoc = Lexer::getLocForEndOfToken(

clang-tools-extra/docs/ReleaseNotes.rst

@@ -174,6 +174,11 @@ Changes in existing checks
   <clang-tidy/checks/modernize/use-override>` check to also remove any trailing
   whitespace when deleting the ``virtual`` keyword.
 
+- Improved :doc:`readability-implicit-bool-conversion
+  <clang-tidy/checks/readability/implicit-bool-conversion>` check to provide
+  valid fix suggestions for ``static_cast`` without a preceding space and
+  fixed problem with duplicate parentheses in double implicit casts.
+
 - Improved :doc:`readability-redundant-inline-specifier
   <clang-tidy/checks/readability/redundant-inline-specifier>` check to properly
   emit warnings for static data member with an in-class initializer.

clang-tools-extra/test/clang-tidy/checkers/readability/implicit-bool-conversion.cpp

@@ -524,3 +524,12 @@ namespace PR71867 {
     // CHECK-FIXES: return (x ? 1 : 0) != 0;
   }
 }
+
+namespace PR71848 {
+  int fun() {
+    bool foo = false;
+    return( foo );
+// CHECK-MESSAGES: :[[@LINE-1]]:11: warning: implicit conversion 'bool' -> 'int' [readability-implicit-bool-conversion]
+// CHECK-FIXES: return static_cast<int>( foo );
+  }
+}