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  1. 01 Nov, 2013 2 commits
    • Andrew Gerrand's avatar
      [release-branch.go1.2] cmd/cgo: stop using compiler error message text to analyze C names · 265ff83a
      Andrew Gerrand authored 
      ««« CL 15070043 / 90a628ac54ed
cmd/cgo: stop using compiler error message text to analyze C names

The old approach to determining whether "name" was a type, constant,
or expression was to compile the C program

        name;

and scan the errors and warnings generated by the compiler.
This requires looking for specific substrings in the errors and warnings,
which ties the implementation to specific compiler versions.
As compilers change their errors or drop warnings, cgo breaks.
This happens slowly but it does happen.
Clang in particular (now required on OS X) has a significant churn rate.

The new approach compiles a slightly more complex program
that is either valid C or not valid C depending on what kind of
thing "name" is. It uses only the presence or absence of an error
message on a particular line, not the error text itself. The program is:

        // error if and only if name is undeclared
        void f1(void) { typeof(name) *x; }

        // error if and only if name is not a type
        void f2(void) { name *x; }

        // error if and only if name is not an integer constant
        void f3(void) { enum { x = (name)*1 }; }

I had not been planning to do this until Go 1.3, because it is a
non-trivial change, but it fixes a real Xcode 5 problem in Go 1.2,
and the new code is easier to understand than the old code.
It should be significantly more robust.

Fixes #6596.
Fixes #6612.

R=golang-dev, r, james, iant
CC=golang-dev
https://golang.org/cl/15070043
»»»

R=golang-dev
CC=golang-dev
https://golang.org/cl/20060044
      265ff83a
    • Andrew Gerrand's avatar
      [release-branch.go1.2] cmd/gc: shorten name used for map bucket type · c57029d4
      Andrew Gerrand authored 
      ««« CL 15110044 / 95336afd420c
cmd/gc: shorten name used for map bucket type

Before:
type.struct { buckets *struct { overflow *struct { overflow *struct { overflow *struct { overflow *struct { overflow *<...>; keys [8]string; values [8]*"".RangeTable }; keys [8]string; values [8]*"".RangeTable }; keys [8]string; values [8]*"".RangeTable }; keys [8]string; values [8]*"".RangeTable }; keys [8]string; values [8]*"".RangeTable }; oldbuckets *struct { overflow *struct { overflow *struct { overflow *struct { overflow *struct { overflow *<...>; keys [8]string; values [8]*"".RangeTable }; keys [8]string; values [8]*"".RangeTable }; keys [8]string; values [8]*"".RangeTable }; keys [8]string; values [8]*"".RangeTable }; keys [8]string; values [8]*"".RangeTable } }

After:
type.map.bucket[string]*"".RangeTable

This makes debugging maps a little nicer, and it takes up less space in the binary.

R=golang-dev, r
CC=golang-dev, khr
https://golang.org/cl/15110044
»»»

R=golang-dev
CC=golang-dev
https://golang.org/cl/20050044
      c57029d4
  3. 31 Oct, 2013 3 commits
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