logging/app: make test more robust

also note that the output of `cargo run` may not match what you get locally if
using a different toolchain

Author: japaric

ci/script.sh

@@ -134,16 +134,35 @@ main() {
     # # Logging with symbols
     pushd logging
 
-    # check that the output and disassembly matches
+    # check that the ~output~ and disassembly matches
+    # the output won't exactly match because addresses of static variables won't
+    # remain the same when the toolchain is updated. Instead we'll that the
+    # printed address is contained in the output of `cargo objdump -- -t`
     pushd app
-    diff dev.out \
-         <(cargo run)
-    diff dev.objdump \
-         <(cargo objdump --bin app -- -t | grep '\.rodata\s*0*1\b')
-    diff release.out \
-         <(cargo run --release)
-    diff release.objdump \
-         <(cargo objdump --bin app --release -- -t | grep '\.rodata\s*0*1\b')
+    cargo run > dev.out
+    cargo objdump --bin app -- -t | grep '\.rodata\s*0*1\b' > dev.objdump
+    for address in $(cat dev.out); do
+        grep ${address#0x} dev.objdump
+    done
+
+    cargo run --release > release.out
+    cargo objdump --bin app --release -- -t | grep '\.rodata\s*0*1\b' > dev.objdump
+    for address in $(cat release.out); do
+        grep ${address#0x} release.objdump
+    done
+
+    # sanity check the committed files
+    git checkout dev.out
+    git checkout dev.objdump
+    for address in $(cat dev.out); do
+        grep ${address#0x} dev.objdump
+    done
+
+    git checkout release.out
+    git checkout release.objdump
+    for address in $(cat release.out); do
+        grep ${address#0x} release.objdump
+    done
     edition_check
     popd
 

src/logging.md

@@ -104,6 +104,10 @@ $ qemu-system-arm \
 {{#include ../ci/logging/app/dev.out}}
 ```
 
+> **NOTE**: These addresses may not be the ones you get locally because
+> addresses of `static` variable are not guaranteed to remain the same when the
+> toolchain is changed (e.g. optimizations may have improved).
+
 Now we have two addresses printed to the console.
 
 ## Decoding