C89 allowed a type specifier to be elided with the resulting type being
int, aka implicit int behavior. This feature was subsequently removed
in C99 without a deprecation period, so implementations continued to
support the feature. Now, as with implicit function declarations, is a
good time to reevaluate the need for this support.
This patch allows -Wimplicit-int to issue warnings in C89 mode (off by
default), defaults the warning to an error in C99 through C17, and
disables support for the feature entirely in C2x. It also removes a
warning about missing declaration specifiers that really was just an
implicit int warning in disguise and other minor related cleanups.
Now with concepts support merged and mostly complete, we do not need -fconcepts-ts
(which was also misleading as we were not implementing the TS) and can enable
concepts features under C++2a. A warning will be generated if users still attempt
to use -fconcepts-ts.
Function trailing requires clauses now parsed, supported in overload resolution and when calling, referencing and taking the address of functions or function templates.
Differential Revision: https://reviews.llvm.org/D43357
Summary:
This change implements parse-only acceptance of the optional
requires-clause in a template-declaration. Diagnostic testing is added
for cases where the grammar is ambiguous with the expectation that the
longest token sequence which matches the syntax of a
constraint-expression is consumed without backtracking.
Reviewers: faisalv, fraggamuffin, rsmith
Reviewed By: rsmith
Subscribers: cfe-commits
Differential Revision: http://reviews.llvm.org/D10462
llvm-svn: 240611
Aaron Ballman