[PATCH] Fix "warning: fallthrough annotation does not directly precede switch label" in lambdas.

[Aaron Ballman]

> Index: lib/Sema/AnalysisBasedWarnings.cpp
> ===================================================================
> --- lib/Sema/AnalysisBasedWarnings.cpp
> +++ lib/Sema/AnalysisBasedWarnings.cpp
> @@ -1025,6 +1025,9 @@
>      // methods separately.
>      bool TraverseDecl(Decl *D) { return true; }
>
> +    // We analyze lambda bodies separately. Skip them here.
> +    bool TraverseLambdaBody(LambdaExpr *LE) { return true; }
> +
>    private:
>
>      static const AttributedStmt *asFallThroughAttr(const Stmt *S) {
> @@ -1084,6 +1087,9 @@
>    if (PerFunction && FM.getFallthroughStmts().empty())
>      return;
>
> +  llvm::errs() << "DiagnoseSwitchLabelsFallthrough: \n";
> +  AC.getBody()->dumpColor();

This looks like debugging code that should likely go away.

> +
>    CFG *Cfg = AC.getCFG();
>
>    if (!Cfg)
> Index: test/SemaCXX/switch-implicit-fallthrough.cpp
> ===================================================================
> --- test/SemaCXX/switch-implicit-fallthrough.cpp
> +++ test/SemaCXX/switch-implicit-fallthrough.cpp
> @@ -229,25 +229,6 @@
>    return n;
>  }
>
> -int fallthrough_targets(int n) {
> -  [[clang::fallthrough]]; // expected-error{{fallthrough annotation is outside switch statement}}
> -
> -  [[clang::fallthrough]]  // expected-error{{fallthrough attribute is only allowed on empty statements}}
> -  switch (n) {
> -    case 121:
> -      n += 400;
> -      [[clang::fallthrough]]; // no warning here, correct target
> -    case 123:
> -      [[clang::fallthrough]]  // expected-error{{fallthrough attribute is only allowed on empty statements}}
> -      n += 800;
> -      break;
> -    [[clang::fallthrough]]    // expected-error{{fallthrough attribute is only allowed on empty statements}} expected-note{{did you forget ';'?}}
> -    case 125:
> -      n += 1600;
> -  }
> -  return n;
> -}

Why did this test move within the file?

> -
>  // Fallthrough annotations in local classes used to generate "fallthrough
>  // annotation does not directly precede switch label" warning.
>  void fallthrough_in_local_class() {
> @@ -259,12 +240,34 @@
>            [[clang::fallthrough]]; // no diagnostics
>          case 1:
>            x++;
> +        default: // \
> +            expected-warning{{unannotated fall-through between switch labels}} \
> +            expected-note{{insert 'break;' to avoid fall-through}}
>            break;
>        }
>      }
>    };
>  }
>
> +// Fallthrough annotations in lambdas used to generate "fallthrough
> +// annotation does not directly precede switch label" warning.
> +void fallthrough_in_lambda() {
> +  (void)[] {
> +    int x = 0;
> +    switch (x) {
> +    case 0:
> +      x++;
> +      [[clang::fallthrough]]; // no diagnostics
> +    case 1:
> +      x++;
> +    default: // \
> +        expected-warning{{unannotated fall-through between switch labels}} \
> +        expected-note{{insert 'break;' to avoid fall-through}}
> +      break;
> +    }
> +  };
> +}
> +
>  namespace PR18983 {
>    void fatal() __attribute__((noreturn));
>    int num();
> @@ -278,3 +281,22 @@
>      }
>    }
>  }
> +
> +int fallthrough_targets(int n) {
> +  [[clang::fallthrough]]; // expected-error{{fallthrough annotation is outside switch statement}}
> +
> +  [[clang::fallthrough]]  // expected-error{{fallthrough attribute is only allowed on empty statements}}
> +  switch (n) {
> +    case 121:
> +      n += 400;
> +      [[clang::fallthrough]]; // no warning here, correct target
> +    case 123:
> +      [[clang::fallthrough]]  // expected-error{{fallthrough attribute is only allowed on empty statements}}
> +      n += 800;
> +      break;
> +    [[clang::fallthrough]]    // expected-error{{fallthrough attribute is only allowed on empty statements}} expected-note{{did you forget ';'?}}
> +    case 125:
> +      n += 1600;
> +  }
> +  return n;
> +}
>

~Aaron

On Mon, Jun 23, 2014 at 11:23 AM, Alexander Kornienko <alexfh at google.com> wrote:
> Hi rsmith,
>
> http://reviews.llvm.org/D4258
>
> Files:
>   lib/Sema/AnalysisBasedWarnings.cpp
>   test/SemaCXX/switch-implicit-fallthrough.cpp
>
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