if/while/switch/for statements to ensure that walking the children of
these statements actually works. Previously, we stored the condition
variable as a VarDecl. However, StmtIterator isn't able to walk from a
VarDecl to a set of statements, and would (in some circumstances) walk
beyond the end of the list of statements, cause Bad Behavior.
In this change, we've gone back to representing the condition
variables as DeclStmts. While not as memory-efficient as VarDecls, it
greatly simplifies iteration over the children.
Fixes the remainder of <rdar://problem/8104754>.
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about the permitted scopes. Specifically:
1) Permit labels and gotos to appear after a prologue of variable initializations.
2) Permit indirect gotos to jump out of scopes that don't require cleanup.
3) Diagnose possible attempts to indirect-jump out of scopes that do require
cleanup.
This requires a substantial reinvention of the algorithm for checking indirect
goto. The current algorithm is Omega(M*N), with M = the number of unique
scopes being jumped from and N = the number of unique scopes being jumped to,
with an additional factor that is probably (worst-case) linear in the depth
of scopes. Thus the entire thing is likely cubic given some truly bizarre
ill-formed code; on well-formed code the additional factor collapses to
an amortized constant (when amortized over the entire function) and so
the algorithm is quadratic. Even this requires every label to appear in
its own scope, which would be very unusual for indirect-goto code (and
extremely unlikely for well-formed code); it is far more likely that
all labels will be in the same scope and so the algorithm becomes linear.
For such a marginal feature, I am fairly happy with this result.
(this is using JumpDiagnostic's definition of scope, where successive
variables in a block appear in their own scope)
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statements. Instead of the @try having a single @catch, where all of
the @catch's were chained (using an O(n^2) algorithm nonetheless),
@try just holds an array of its @catch blocks. The resulting AST is
slightly more compact (not important) and better represents the actual
language semantics (good).
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a fixme and PR6451.
Only perform jump checking if the containing function has no errors,
and add the infrastructure needed to do this.
On the testcase in the PR, we produce:
t.cc:6:3: error: illegal goto into protected scope
goto later;
^
t.cc:7:5: note: jump bypasses variable initialization
X x;
^
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The implementations of these methods can Use Decl::getASTContext() to get the ASTContext.
This commit touches a lot of files since call sites for these methods are everywhere.
I used pre-tokenized "carbon.h" and "cocoa.h" headers to do some timings, and there was no real time difference between before the commit and after it.
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